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Fiero V6 Fuel Injected Engine Problems by altownsend
Started on: 05-27-2020 10:40 AM
Replies: 27 (625 views)
Last post by: altownsend on 06-07-2020 10:51 PM
altownsend
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Report this Post05-27-2020 10:40 AM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
I purchased a replica project with a 1986 Fiero base.

1986 Fiero, V6 Fuel Injected,4 Speed Manual

The fuel tank has fresh gas, new fuel filter, no visible or obvious vacuum leaks detected. Recently did a standard tune-up (Plugs, wires, distributor cap, rotor, sensors - temperature, idle speed). Alternator charging at 13.3 to 13.8 volts. Right now, the engine does not seem to be misfiring. Battery is new.

The engine starts after a few turns. It will hold idle until about the time that it gets up to Normal Operating Temperature. the idle will drop at Normal Operating Temperature, and it will eventually stall out. I have checked the fuel pressure, and it remained the same through this cycle. If the engine runs long enough, it gets hot enough for the fan to activate, and the fan turns off when the temperature drops.

However, the problem is that the engine will not remain at idle. It will stall out. There was a recent time (2019) that it ran until I turned the ignition off. But, now, it stalls out at idle.

Is there a Fiero V6 expert/tech person here that can spend some time with me to figure out what the problem is? I am in Houston Texas.
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Report this Post05-28-2020 09:47 PM Click Here to See the Profile for SpoonSend a Private Message to SpoonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Right after it stalls out can you restart it easily without pressing on the gas? Did you apply a fresh layer of thermo paste under the ignition module?
What is your normal idle rpm? Does it stall out while driving down the road or only when your foot is off the gas pedal?
Have you checked the IAC valve on the throttle body for carbon fouling.
Does it stall out with rpms gradually getting lower & lower Or does it try to save itself with a See-Saw type idle?

Check EGR pipe between intake manifold and EGR valve. It usually has a heat insulating wrap around it so its hard to see. May have to remove the tube to be sure, 2 bolts /2 nuts.
Another vac leak source is a short rubber hose (with 90 degree bend) hidden behind the throttle body. connecting it to the intake manifold.

Check for proper grounding. Replace broken or missing ground straps. Engine block to frame, body to frame and chassis , etc. Can also check with a cheap Harbor Freight meter set to ohms.

I'm no expert but they should be along shortly...

Spoon


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Report this Post05-29-2020 01:03 AM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post

Spoon,

Thank you for the questions. You brought to surface some new information for me to consider. Thanks for that. My response to your questions is below:

------
Right after it stalls out can you restart it easily without pressing on the gas?

- I can restart the engine after it stalls, but it stalls again right away. However, if I feather the gas pedal, it will run again, but roughly, and it will not run smoothly again until the next time that I do a cold start again.

Did you apply a fresh layer of thermo paste under the ignition module?

-No, I did not install a layer of thermo paste under the ignition module. Please tell me more about that, and I will make the adjustment to say 'Yes" next time.

What is your normal idle rpm?

- Normal idle is about 1,000 RPM or so, maybe just under 1,000 RPM

Does it stall out while driving down the road or only when your foot is off the gas pedal?

- I purchased this project from someone whom purchased it from someone whom purchased it from someone (I am the 7th owner of the project) It has never, to my knowledge been on the street as a driver. So, from time to time, I start the engine to use up the fuel, so that I can put fresh gas in the tank. Lately, the engine has not ran for very long with the idle issue

By the way, I have fresh oil with new filter, new fuel filter, new sensors (including IAC)

Now, with what I just said, I have experienced the engine running until I got bored and turned the engine off, hence the engine ran until I decided to turned it off. Now, that was also when I had the idle air control sensor off. I have had this idle problem all along. Research suggested that I replace the idle air control sensor (IAC) located on the throttle body. With it off, the engine will run until it runs out of fuel or I turn the engine off. With the sensor off, the engine starts, idles without fluctuating, and has no issues. Now that we are discussing this, I will remove the new sensor again and see if the engine will run as 'normal'.

Have you checked the IAC valve on the throttle body for carbon fouling.

-Yes, I replaced it. With it off, the engine runs fine. With it installed, the engine will start and run fine until the engine gets up to normal operating temperature, and then the engine will reduce idle and eventually quickly stall.

Does it stall out with rpms gradually getting lower & lower Or does it try to save itself with a See-Saw type idle?

-the engine runs fine with no intervention when I do a cold start. It runs at 1,000 or just below 1,000 with consistency, and then, at normal operating temperature, it slows and stalls within 10 seconds of the first sign of RPM change.

Check EGR pipe between intake manifold and EGR valve. It usually has a heat insulating wrap around it so its hard to see. May have to remove the tube to be sure, 2 bolts /2 nuts.

- Yes, I removed the EGR pipe and checked for obstructions, wear, pin holes, damage. With the exception of the gasket (did not replace the gasket) there was no seemingly visible damage. I cleaned the pipe, however, it did not need cleaning.

Another vac leak source is a short rubber hose (with 90 degree bend) hidden behind the throttle body. connecting it to the intake manifold.

- yes, I know this hose, and I removed it and assessed it when I took the intake cover off. It was flexible, not rotted or torn or brittle. It fit properly and had no visible defect.

Check for proper grounding. Replace broken or missing ground straps. Engine block to frame, body to frame and chassis , etc. Can also check with a cheap Harbor Freight meter set to ohms.

- Okay, this one needs intervention. I read about grounding and have some grounding from the engine to the chassis. So, to have the engine properly grounded, please share with me where the grounds are supposed to be, and I will confirm that I have the proper grounding for proper engine functionality.

Note: I have checked the charging by testing voltage at the battery with the engine running using my volt meter. I get 13.3 to 13.8 volts fluctuating between those two points. The engine has never not started even though the car sits for long periods of time.

Note: I have sprayed carb cleaner on all of the vacuum connections and around the intake looking for a change in engine RPM to identify vacuum leaks. None to date.

Note: I have no oil leaks or water/fluid leaks. The engine heats up and does not smoke, either the engine itself or though the tail pipes.

Note: Each time that I start the engine, I have to turn the engine over several times to finally hear the fuel pump activate. For instance. First start (cold), I turn the ignition over for a few engine revolutions and release the key. No fuel pump engage. Second spin and release, no fuel pump, third, and sometimes a forth spin and no fuel pump. Finally I turn the ignition and release and hear the fuel pump activate. the very next time that the ignition turns the engine, the starts and keeps running until it gets to normal operating temperature when it eventually stalls. It will restart, but sounds and performs as though is is starving for gas or has an obstruction. At cold start, it runs for about 5 minutes with no problem.

Well, there you have it. Any ideas for a fix, please?
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Report this Post05-29-2020 02:10 AM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:

Each time that I start the engine, I have to turn the engine over several times to finally hear the fuel pump activate. For instance. First start (cold), I turn the ignition over for a few engine revolutions and release the key. No fuel pump engage. Second spin and release, no fuel pump, third, and sometimes a forth spin and no fuel pump. Finally I turn the ignition and release and hear the fuel pump activate. the very next time that the ignition turns the engine, the starts and keeps running until it gets to normal operating temperature when it eventually stalls. It will restart, but sounds and performs as though is is starving for gas or has an obstruction. At cold start, it runs for about 5 minutes with no problem.


You have more than one problem.

The fuel pump should run for two seconds each time you turn the key to ON. Check the relay. You are presently relying on oil pressure to trigger the fuel pump. (It's a secondary fuel pump control.)

What is your fuel pressure, both while the engine is running, and after it's turned off?
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Report this Post05-29-2020 09:14 AM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Patrick,

Thanks for the question.

the fuel pump relay and the A/C relay were replaced. I replaced them before I replaced the IAC. And, Patrick, the starting process was the same before the relay was replaced. so, after a new relay was installed, the problem did not go away.

I do not remember the fuel pressure at the rail. I did, however, check it when the fuel pump pressurized the 'system', and while the engine was running. The reading was about the same. However, I will check it again and report the readings.
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Report this Post05-29-2020 04:04 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:

the fuel pump relay and the A/C relay were replaced. I replaced them before I replaced the IAC. And, Patrick, the starting process was the same before the relay was replaced. so, after a new relay was installed, the problem did not go away.


Well, there's still something wrong. There are other people here who can describe the interplay in more precise detail... but when the ignition key is turned to ON, I believe the ECM energizes the fuel pump relay for two seconds. Your car isn't doing this, but the reason why you eventually get it to start is that once oil pressure is built up (from multiple engine cranks), it's the oil pressure sender which is energizing the fuel pump relay. However, I'm not sure if it's the same relay or not. I've never had these issues with any of my Fieros, so I don't know the finer details of the fuel pump electrical system.
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Report this Post05-29-2020 10:01 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
[img]//images.fiero.nl/userimages/altownsend/Engine%20Runni ng%20Unplugged%20Throttle%20Position%20Sensor.jpg[/img]

Based on new information from this post, I ran three tests:

1) I screwed my fuel pressure gauge to the fuel rail fitting. I turned the engine over a few times and finally heard the fuel pump activate. I checked the fuel pressure gauge and there was no reading. The engine started and I looked at the pressure gauge and saw the gauge reading 45PSI. While the engine was running, the gauge went from 45PSI to 50PSI down to 40PSI at the higher RPM idle with the idle speed sensor unplugged.

2) I unplugged the idle speed sensor and the car ran for about 30 minutes at which time I turned it off. I re-attached the idle speed sensor, and the engine started buy stalled almost immediately. I unplugged the idle speed sensor, and the RPM stabilized and the engine kept running.

3) In the photo labeled "Filter of some sort', there is a filter that is attached to a hose that is connected to either the fuel rail or the intake. Can someone tell me what that filter is for (what it filters)?


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Report this Post05-29-2020 10:40 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:

I screwed my fuel pressure gauge to the fuel rail fitting. I turned the engine over a few times and finally heard the fuel pump activate. I checked the fuel pressure gauge and there was no reading. The engine started and...


No fuel pressure and it started?

 
quote
Originally posted by altownsend:

...idle speed sensor


What exactly are you referring to? The idle control valve? The throttle position sensor?

 
quote
Originally posted by altownsend:

In the photo labeled "Filter of some sort'...


???


 
quote
Originally posted by Patrick:

What is your fuel pressure, both while the engine is running, and after it's turned off?


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Report this Post05-30-2020 12:59 AM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Patrick.



No fuel pressure and it started?
- yes, fuel pressure was 45PSI when I looked at it after the engine started. It could have built up as the engine was spinning.


...idle speed sensor
-see photo, throttle position sensor (the one sensor on the top)




What exactly are you referring to? The idle control valve? The throttle position sensor?
- throttle Position Sensor - when I unplug it, the engine runs for as long as I let it, at a higher RPM


In the photo labeled "Filter of some sort'...
- the silver filter. It does not filter liquid (gas). Is it an air filter? One end goes under and into the cabin, the other to the intake plenum


What is your fuel pressure, both while the engine is running, and after it's turned off?

-While running with the Throttle Position Sensor plugged in, 45PSI
-With the Throttle Position sensor unplugged, 40PSI
- it was at 50PSI at one point

With engine off, it stays at 45PSI, and then it gradually falls to under 30PSI over a period of time

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Report this Post05-30-2020 02:55 AM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:

With engine off, it stays at 45PSI, and then it gradually falls to under 30PSI over a period of time


"Under 30PSI"? How far under?

"Period of time"? Are you talking two seconds, five minutes, one hour?

These questions are to help determine if you have fuel leaking from injectors, regulator etc.
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Report this Post05-30-2020 01:32 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Acknowledged,


"Under 30PSI"? How far under?

-On May 29, I did my test, and I unplugged the fuel pressure gauge as I closed the work down on that session. From the time that I shut the engine down and last looked at the gauge with it reading at 30PSI was about 45 minutes. I remember being surprised that it went from 45PSI at engine shutdown to removing the gauge and seeing it at around 30PSI.

Now, to confirm how long it took to go from 45PSI to where it bottomed out, I will test again today and have a definite time frame. I will come back here to report.

"Period of time"? Are you talking two seconds, five minutes, one hour?

Note:

As part of my assessment some time ago, I removed the intake cover, the fuel rails and assessed the condition, visually, and did not see any component to be compromised or, otherwise needing to be replaced.

Side Question: Comments have been made that the fuel pump should activate when the ignition is turned to the 'On' position. What should I test or assess to get the fuel pump to respond to the ignition being turned to the 'On' position?
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Report this Post05-30-2020 04:19 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:

Comments have been made that the fuel pump should activate when the ignition is turned to the 'On' position. What should I test or assess to get the fuel pump to respond to the ignition being turned to the 'On' position?


Your ears. Seriously though, you should easily hear the fuel pump activate for a couple of seconds when the key is turned to ON. (Remember, you're not cranking the engine at this point.) If a fuel pressure gauge is connected, that'll also give you a visual cue. If the fuel pump is not being activated for those two seconds, check the operation of the associated relay.

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Report this Post05-30-2020 11:49 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Patrick,

As stated before, the fuel pump relay was replaced with a new one. Prior to replacing it, I had this problem with the fuel pump not activating until the oil pressure switch powered the relay. So, I did some research and on this medium, learned that replacing the relay was the cure. Okay, I purchased a new fuel pump relay and installed it. I still had the same problem.

Now, that is why, as part of my problem solving with the idle issue, I mentioned, or asked my 'Side Question' about the fuel pump relay in my last post. Again, I still put this question (about the fuel relay activating with the ignition in the 'On' position) out to the audience and hope to attract an expert/knowledgeable person for that issue.

Revisit to the issue with the fuel pump relay: I installed a new fuel relay months ago. I actually replaced both relays (A/C and fuel pump) on that end of the harness. When I turn the ignition to the 'On' position (and listen for the pump to power up), I do not hear the fuel pump activate. After five (5) tries today (Saturday, May 30, 2020), I finally heard the fuel pump power up. The very next turn fired up the engine. So, my question revisited: What can I test or assess to find a fix to getting the fuel pump to activate via the ignition activating it rather than the oil pressure triggering the fuel pump relay?

Today's review of the engine troubleshooting:

Engine Running at idle, all connectors connector (Throttle Position Sensor also)


Engine shut off fuel pressure reading, pressure started dropping about 5 seconds after I shut the engine off.


The purpose of today's assessment was to confirm how the fuel pressure reading behaved before start-up (included listening for the fuel pump to activate when the key is turned to the 'On' position), the reading during engine operation (it was 45PSI), and the fuel pressure reading after the engine shut down (dropped to 40PSI):

1) After the engine shut down, the reading went from 45PSI at operating to 40PSI at engine shut down.
2) Reading went from 40PSI, gradually decreasing slowly to 25PSI in exactly 2.5 minutes.
3) Reading went from 25PSI to 10PSI, thus taking about 3 minutes to get from 25PSI to just above 10PSI which is where it stayed until I removed he gauge.

Note: Today, the engine did not stall. I started with the Throttle Position Sensor connector unplugged. The engine RPM was high. I shut the engine off and plugged in the Throttle Position Sensor connector. The engine started with no problem, and the idle went down to approximately 900 to 1,000 RPM with no fluctuation in RPM. Fuel pressure was at a solid 45PSI, and the engine ran until I decided to turn it off. While the engine was running, there was no variance in the engine RPM.

So, folks, I hope that I was concise in my descriptions of what is happening with the project (engine/fuel pump/fuel pressure reading)

Comments please.
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Report this Post05-31-2020 09:19 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
The fuel pressure numbers are not great, but should run the engine. You should fix the relay problem first, so the car starts as it is supposed to. The first check would be to see if you have 12v. at the orange/black wire at the relay socket (E). Then check for a signal on the Dk green/white wire (A) when you turn the key 'on'. That should only last for about 3 seconds.

of course there is a possibility that you bought a bad new relay.

[This message has been edited by Gall757 (edited 05-31-2020).]

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Report this Post05-31-2020 11:07 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Acknowledged, Gall757,

I did replace both the A/C and the fuel relays. After getting the same result from installing the new fuel pump relay, I switched the relays and did not get a different result.

It has been raining all day, so I was not able to test the circuit as described.

I spoke to my buddy that is a repair person with a GM dealership. He asked me to check the ECM Reset Connector. He stated that this is the circuit that acknowledges the Ignition 'On' position and power the fuel pump relay to prime the pump (3 - 5 seconds)

I agree that I need to solve the fuel relay issue. I am focusing on that.

Now, you mentioned that the fuel pressure was not great. Please share with me what the fuel pressure should be.

And, please tell me if the pressure should drop so rapid;y after engine shut down. I plan to order fuel injector o-rings because I perceive that fuel is leaking past them.

thanks for your comments. Any assessment response is appreciated.
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Report this Post06-01-2020 10:47 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update,

Today, June 1, 2020, I went back to the fuel pump relay prime problem.

I took the connector block (Main block) on top of the engine, passenger side apart to confirm that all of the pins were in place, no damage. They were.

I tested the wiring (Fusible link) for the ECM Reset Connector, and I learned that the wire from the pin inside of the connector to the tip of the wire (ECM Reset Connector) had continuity. It had continuity.

I reattached the connector block and I traced the orange wire on the exit/firewall side of the connector.

I traced the orange wire leading from the ECM Reset Connector to the firewall and confirmed that it went inside the cabin as part of that group of wires:

1) Inside of the cabin, I found the orange ECM Reset Connector wire and cut into it to expose wire. I tested the circuit for 12 volts key on. I did get 12 volts constant with key on, engine off.
2) I noticed that the orange wire split (Y) - see attached photo


3) I cut into both wires and tested and confirmed them for 12 volts constant with key on, engine off.
4) Both wires went to the two separate connectors of the ECM. See photo - upper wire exits the ECM connector and traces to the ALCL port.

5) The voltage testing was as follows:
a: Voltage on both of the orange wires going to the ECM was 12 volts.
b: The wire leading from the connector and ending at the ALCL port measured at 4 volts out of the ECM connector and at the ALCL port terminal.

Question for the pros: What is the required system voltage for the orange wire exiting the connector in the photo (top wire)? Again, my measure was 4 volts at the wire and at the terminal in the ALCL port. Also, please comment on what wire or circuit I can test to confirm or repair the fuel pump prime circuit.

Objective: I want to establish/create a fix that allows the fuel pump relay to power up with key on, engine off, that primes the fuel pump relay circuit.

Summary:
12 volts constant confirmed at the wiring block on the passenger side of the top of the engine
12 volts constant confirmed at the Y inside of the cabin, both Y orange wires going to the ECM separate connectors.
Orange wire coming out of connector to the ALCL port, measuring 4 volts on the wire exit and at the ALCL port terminal.

Comments please

[This message has been edited by altownsend (edited 06-01-2020).]

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Report this Post06-04-2020 04:55 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update,

Today, June 4, 2020, I traced all of the wiring from the fuel pump relay:

From Left to Right in the photo:

GRN/WHT stripe goes from fuel pump relay connector to the PCM (Is this GRN/WHT wire the prime wire)

TAN/WHT strip goes from fuel pump relay connector to the fuel pump. Direct 12 Volts power up the fuel pump

BLK/WHT strip is the ground wire. (Ohms are much lower that testing the Ohm meter leads by touching each other ground to grown testing at engine points.

Orange/black strip wires (two of them) goes into the fuel pump relay connector. One wire comes from the oil pressure switch that feeds the fuel pump. That wire has 12 volts key on. The second wire goes to the inside of the cabin fuse box (10 amp fuse). Fuese is good.

Someone, please assess my comments and offer a solution to my no-prime condition. With key at the 'On' position, the system does not prime. My question relates to the Green wire with white stripe that goes from the fuel pump relay to the PCM. Is this wire the prime wire?

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Report this Post06-04-2020 07:24 PM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
Don't have time to read all of this but Top post says alternator charges at ~ 13v... is a Bad Thing.
Should change at 14.6 to 15 volts measured at alt and battery at minimum. The Rest of car should see close to same but often have crap grounds and more. (And why HL bulbs and fan/blower motors see < 14v w/ engine running even at high idle.)

Part of why didn't bother reading...
you measure volts at alt or battery low then Very Likely ECM and more have every lower volts causing all the rest of problems.
Very possible ECM sees low volts and tries to adjust engine timing etc to try to jack up the volts but not so low will set a code. Depending on ECM programing/version ECM can set a code for too low or too high volts but can't find my notes to say what numbers.
ETA--> Code 53 for Over Volt, Code 75 for Low Volts. Older "OBD1" ECM may not have Code 75 but low volts Will cause ECM and Engine problems. Some or all do have 53 and can get it when alt "dies" making high volts.

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[This message has been edited by theogre (edited 06-04-2020).]

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Report this Post06-04-2020 08:41 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Update,

I did a test on the prime wire (Green with White stripe) to see if there was/is an issue with the voltage getting from the prime wire (green with white stripe) to the Orange/Black stripe fuel pump wire at the fuel pump relay socket.

The following is what I learned:

I first removed the fuel pump relay and ran a jumper from the green wire (prime) to the inside of the cabin to test the voltage at the green/white terminal at the fuel relay. I confirmed a constant 12 volts with key to 'On' position.

So, I went back out to confirm 12 volts constant on the terminal of the green/white stripe wire terminal, voltage was good with key at the 'On' position.
I ran 12 Volts to the fuel pump wire and confirmed that the pump operated at 12 volts. I had the fuel pressure gauge connected to confirm fuel pressure. Fuel pressure was good.

So, I jumped the green/white stripe wire that goes to the PCM to the fuel pump terminal (fuel pump) at the connector. I also set up the volt meter to confirm voltage at the green/white prime wire from the PCM.

I turned the key to the 'On' position and checked for voltage on the meter - confirm 12 volts on the green/white, however, no power on the fuel pump terminal, fuel pump not operating.

I noticed that the fuel pressure gauge/fuel pump were not being affected by applying 12 volts to both the fuel pump wire and the green/white prime wire.

When I applied the green/white wire 12 volts to the fuel pump wire, the voltage dropped to 0 and the fuel pump did not power up.

I took the jumper off and applied a secondary 12 voltage source to the fuel pump wire and the fuel pump powered up.

So folks, someone please tell me what I have.
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Report this Post06-04-2020 08:58 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post

altownsend

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Member since Sep 2019
 
quote
Originally posted by theogre:

Don't have time to read all of this but Top post says alternator charges at ~ 13v... is a Bad Thing.
Should change at 14.6 to 15 volts measured at alt and battery at minimum. The Rest of car should see close to same but often have crap grounds and more. (And why HL bulbs and fan/blower motors see < 14v w/ engine running even at high idle.)

Part of why didn't bother reading...
you measure volts at alt or battery low then Very Likely ECM and more have every lower volts causing all the rest of problems.
Very possible ECM sees low volts and tries to adjust engine timing etc to try to jack up the volts but not so low will set a code. Depending on ECM programing/version ECM can set a code for too low or too high volts but can't find my notes to say what numbers.
ETA--> Code 53 for Over Volt, Code 75 for Low Volts. Older "OBD1" ECM may not have Code 75 but low volts Will cause ECM and Engine problems. Some or all do have 53 and can get it when alt "dies" making high volts.


theogre,

Thanks for the voltage comments. Please know that I do a lot of testing of electrical systems, and leave the ignition on for long periods of time. This is one of the reasons why my tested voltage is around 12 volts. The testing is done on systems and not at the alternator or the battery.

You mentioned that my problem could be electrical.

Now, the car is a Lambo replica in the works, so the electrical systems, with exceptions, are not operational, so I don't have Check Engine, or am able to pull codes. I will check voltage on Friday. I also have not fully tightened the battery terminals.

So, with today's testing, do you have input to the fuel pump prime issue?

[This message has been edited by altownsend (edited 06-04-2020).]

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Report this Post06-05-2020 09:37 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:
theogre,

Thanks for the voltage comments. Please know that I do a lot of testing of electrical systems, and leave the ignition on for long periods of time. This is one of the reasons why my tested voltage is around 12 volts. The testing is done on systems and not at the alternator or the battery.

You mentioned that my problem could be electrical.

Now, the car is a Lambo replica in the works, so the electrical systems, with exceptions, are not operational, so I don't have Check Engine, or am able to pull codes. I will check voltage on Friday. I also have not fully tightened the battery terminals.

So, with today's testing, do you have input to the fuel pump prime issue?
Test volts at the alt and/or battery First Then other places when needed.

Engine off, battery @ 12 v is nearly dead. Draining battery lower is trouble and short life of it. See my Cave, Battery

"Fiero Type/Class" FP primes itself in milliseconds and rest of system a few seconds later max when completely dry if fuel system is plumbed correct. Is Why OE systems have return line from the injector rail or TBI. Wet system just need full pressure and happens very fast if pump etc is good.
New cars w/ reg in the tank and swaps w/ 3 port remote reg just waits for injectors to purge air when first started and happens w/o your help and fast too.
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Report this Post06-05-2020 06:27 PM Click Here to See the Profile for RexgirlSend a Private Message to RexgirlEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by altownsend:

Update,

I turned the key to the 'On' position and checked for voltage on the meter - confirm 12 volts on the green/white, however, no power on the fuel pump terminal, fuel pump not operating.

I noticed that the fuel pressure gauge/fuel pump were not being affected by applying 12 volts to both the fuel pump wire and the green/white prime wire.

When I applied the green/white wire 12 volts to the fuel pump wire, the voltage dropped to 0 and the fuel pump did not power up.

I took the jumper off and applied a secondary 12 voltage source to the fuel pump wire and the fuel pump powered up.

So folks, someone please tell me what I have.



It appears your new relay is not providing full current to the fuel pump. Re-test to confirm you still have 12 vdc at the relay plug's green/white wire for 2-3 seconds after turning the ignition on.
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Report this Post06-06-2020 03:12 AM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Rexgirl,

Okay, today, Friday, June 6, 2020, I really focused on the relay and systems associated with it.

At the fuel pump relay:

Black/White stripe confirmed working ground.
Orange/Black stripe (wire one goes to the oil pressure switch) reads continuity from oil pressure switch to fuel pump relay connector plug.
Second Orange/ Black stripe wire confirmed coming from fuse box (10 amp) and was battery voltage at the fuel pump relay connector terminal.

Tan w/stripe goes to the fuel pump. I bridged/jumped battery voltage to the Tan w/Strip with the fuel pressure gauge connected, and I confirmed by hearing the pump power up and observed the fuel pressure show 45 PSI on the gauge.

Now, here is where I was and still am confused:

Green wire w/White stripe runs from fuel pump relay to PCM. I measured this wire a variety of ways and found the following conclusions:

Relay removed from Plug:
No voltage reading with key off
With Key 'On' and volt meter attached to the Green wire with white stripe, meter shows constant battery power. (Note: the power does not come on for a few seconds and goes dead after that few seconds). The battery voltage is read at key 'On' and retains battery voltage as long as the key is in the 'On' position.

When I jump between the Green w/stripe wire (Prime/wake up wire), and the fuel pump lead, neither the fuel pump powered up nor the volt meter showed battery voltage. So, I removed the jump and turned the key to the 'On" position again and read battery voltage on the Green/White stripe wire again.

With the meter connected, I installed the relay. Again, I checked the voltage between the Green stripped wire and and the fuel pump wire. No voltage reading, and not power to the fuel pump. Again, I have voltage on the Green/White stripe wire with no load on it.


So, I did another type of test. With the volt meter in series, I set up a test light. The test light was confirmed working with battery voltage applied. When the test light is put in series with the Green/White striped wire to the test light, the test light does not power up, nor does the volt meter register battery voltage.

Conclusion:

The Green/White striped wire holds battery voltage when the key is turned On.
When an electrical load is put on the circuit, the circuit will not record voltage.
This is the case no matter if the relay is in the plug or not.

Comments please


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Report this Post06-06-2020 09:19 AM Click Here to See the Profile for theogreClick Here to visit theogre's HomePageSend a Private Message to theogreEdit/Delete MessageReply w/QuoteDirect Link to This Post
ECM/PCM Sends Power to the Relay via Dk Grn/Wht wire to Turn On.
If ECM does not send Power then likely bad ECM or if rewired to use non-OE unit then wiring is wrong or ECM/PCM is bad.

If ECM or you sends power and relay doesn't turn on then likely relay is bad.
If car has AC just switch relays to quick test for bad relay.

Or Plugs might have damaged since your or others messing w/ them. Plugs are tough but don't like people pushing crap into them to measure, etc.
Plug "pins" are removable same way w/ release tool push in small slot in front in my Cave, Defect & Connection notes
Grease is "bulb grease" to protect. Can get more at many local part stores. often sold on parts counters along w/ other types in foil packs.
Only pull 1 "pin" at a time!

If you find a pin too damage to fix easy... Get a pig tail "kit" and replace just damage ends. Don't cut good ends.
If needed just move them to new shell one at a time to make sure you move to right holes.
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Report this Post06-06-2020 11:28 AM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Rexgirl,

Okay, today, Friday, June 6, 2020, I really focused on the relay and systems associated with it.

At the fuel pump relay:

Black/White stripe confirmed working ground.
Orange/Black stripe (wire one goes to the oil pressure switch) reads continuity from oil pressure switch to fuel pump relay connector plug.
Second Orange/ Black stripe wire confirmed coming from fuse box (10 amp) and was battery voltage at the fuel pump relay connector terminal.

Tan w/stripe goes to the fuel pump. I bridged/jumped battery voltage to the Tan w/Strip with the fuel pressure gauge connected, and I confirmed by hearing the pump power up and observed the fuel pressure show 45 PSI on the gauge.

Now, here is where I was and still am confused:

Green wire w/White stripe runs from fuel pump relay to PCM. I measured this wire a variety of ways and found the following conclusions:

Relay removed from Plug:
No voltage reading with key off
With Key 'On' and volt meter attached to the Green wire with white stripe, meter shows constant battery power. (Note: the power does not come on for a few seconds and goes dead after that few seconds). The battery voltage is read at key 'On' and retains battery voltage as long as the key is in the 'On' position.

When I jump between the Green w/stripe wire (Prime/wake up wire), and the fuel pump lead, neither the fuel pump powered up nor the volt meter showed battery voltage. So, I removed the jump and turned the key to the 'On" position again and read battery voltage on the Green/White stripe wire again.

With the meter connected, I installed the relay. Again, I checked the voltage between the Green stripped wire and the fuel pump wire. No voltage reading, and no power to the fuel pump. Again, I have voltage on the Green/White stripe wire with no load on it. but, when I apply power (Key on), the voltage reads zero. Take the jumper off of the fuel pump wire, voltage comes back as reading battery voltage to the green/White stripe wire.


So, I did another type of test. With the volt meter in series, I set up a test light. The test light was confirmed working with battery voltage applied. When the test light is put in series with the Green/White striped wire to the test light, the test light does not power up, nor does the volt meter register battery voltage.

Conclusion:

The Green/White striped wire holds battery voltage when the key is turned On.
When an electrical load is put on the circuit, the circuit will not record voltage.
This is the case no matter if the relay is in the plug or not.

Comments please


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Report this Post06-06-2020 12:25 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post

altownsend

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Member since Sep 2019
***ECM/PCM Sends Power to the Relay via Dk Grn/Wht wire to Turn On.
***If ECM does not send Power then likely bad ECM or if rewired to use non-OE unit then wiring is wrong or ECM/PCM is bad.

- PCM does sent battery voltage through GRN/White stripe wire to the fuel pump relay. Voltage tested and confirmed at the plug terminal. Voltage is constant, not for only 2 - 3 seconds. Again, voltage is 'On' and reads constant. - - Power does get to fuel pump relay plug terminal with key on - -


***If ECM or you sends power and relay doesn't turn on then likely relay is bad.
***If car has AC just switch relays to quick test for bad relay.

-Relay does get power from two sources
Source 1 (Primary) - power from fuse box
Source 2 (PCM) - power from PCM with key 'On'

***Or Plugs might have damaged since your or others messing w/ them. Plugs are tough but don't like people pushing crap into them to measure, etc.
Plug "pins" are removable same way w/ release tool push in small slot in front in my Cave, Defect & Connection notes
Grease is "bulb grease" to protect. Can get more at many local part stores. often sold on parts counters along w/ other types in foil packs.
Only pull 1 "pin" at a time!

- Fuel pump relay plug has been tested for status:
Test for ground terminal: Using Ohm meter, ground wire terminal at the plug was tested for continuity: Pass
Test for Oil Pressure wire (Orange w/Black trace stripe): Using Ohm meter, Oil Pressure Orange w/Black tracer wire tested at the plug terminal for continuity: Pass
Test for second Orange w/Black tracer stripe (10 amp fuse box): Using volt meter to test fuel pump relay plug terminal for battery voltage: Pass
Test on Tan wire leading to fuel pump: Ran battery voltage to the fuel pump relay plug terminal, fuel pump powers on: Pass
Test on GRN w/White stripe from PCM: Tested battery voltage at the fuel pump relay plug terminal for battery voltage from PCM, key 'On': pass

- Both A/C and fuel pump relays were 3 months old. I initially interchanged them to test for defective relay. No change in Prime circuit. On Friday, June 5, 2020, I purchased a new fuel pump relay, installed it, and, no change.

- All terminals on the existing fuel pump relay plug have proven to be adequate for their intended purpose.

Resolution please

[This message has been edited by altownsend (edited 06-06-2020).]

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Report this Post06-07-2020 07:04 PM Click Here to See the Profile for RexgirlSend a Private Message to RexgirlEdit/Delete MessageReply w/QuoteDirect Link to This Post
Your test appear to confirm your relay and it's wiring are working as they should. This leaves the engine computer as the likely cause. While the Green/White wire shows 12 vdc, the fact that it remains powered on after 2-3 seconds, and also has too little Current to fully energize the relay's coil, suggests that as Theogre wrote, the ECM/PCM has failed. Sometime in the past, the Green/White wire may have been connected to a low resistance load, and that could have damaged the ECM's relay driver transistor, as ECM sensor and control wires should Only be connected to their specified components.

Hopefully others here might help you with a replacement or loaner ECM for verification.
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Report this Post06-07-2020 10:51 PM Click Here to See the Profile for altownsendSend a Private Message to altownsendEdit/Delete MessageReply w/QuoteDirect Link to This Post
Solution:

Thank those of you who chimed in on my inquiry.

I hope that all of the detail that I typed in every post will help others in their assessment of this problem. As the last person suggested, I concluded that the PCM is defective based on two things:

1) Constant voltage on the 'Trigger Wire' Green w/White stripe from PCM to fuel pump relay plug
2) voltage drop to zero (0), key 'On', voltage test, load applied to 'Trigger Wire'

So, after concluding that the 'Trigger Wire' Green w/White stripe wire from PCM needs 12 volts as a temporary power source, I decided to use the opportunity to put another gadget in the car. So, I have chosen a two wire momentary push button switch to power the relay for whatever period of time I need to prime the fuel system.

I plan to install either a lighted push button switch (One that lights up when pressed), or I will install a light in the dash or console that illuminates when power is applied to the relay. I might even install a fuel pressure gauge inside of the car.

Any way, my problem is solved. I have the push button momentary switch installed, and I tested it on my first start of the day, and it works perfectly. I will install a 10 amp inline fuse on Monday, and this problem will be permanently resolved.
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