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1986 Fiero SE Won't Run by 72and86
Started on: 09-17-2021 02:13 PM
Replies: 55 (663 views)
Last post by: 72and86 on 10-17-2021 11:18 AM
72and86
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Report this Post10-09-2021 07:51 PM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by buddycraigg:


Stop buying stuff.

We need to diagnose the problem.

I cannot help anymore until you tell me what happened when you tried to make it idle with using your finger over the hole when you took the IACM out.


Ok here's chapter 12. As you asked: With the IAC removed the car starts and runs 3000 RPMS for about 8 seconds and dies. With the IAC hole PLUGGED car starts and runs but dies after 3 seconds. Car will run if you keep feeding gas with the throttle, as soon as you let go of the throttle car dies.

[This message has been edited by 72and86 (edited 10-11-2021).]

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72and86
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Report this Post10-09-2021 07:59 PM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by Rexgirl:

I am also wondering if your cold start tube (#5 in pic) is okay and not leaking? It connects under the throttle body and feeds the intake manifold.


See a pic from a few days ago when we took the plenum off. We checked, double-checked and triple checked for leaks or cracks. Everything around the engine looks real good. Wheres this cold start tube?

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Report this Post10-09-2021 08:22 PM Click Here to See the Profile for XenoblastClick Here to Email XenoblastSend a Private Message to XenoblastEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by 72and86:


See a pic from a few days ago when we took the plenum off. We checked, double-checked and triple checked for leaks or cracks. Everything around the engine looks real good. Wheres this cold start tube?



Pretty sure this is it.


also its not a cold start tube its the tube that feeds the engine so that it can idle while the throttle is closed.
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buddycraigg
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Report this Post10-10-2021 03:47 PM Click Here to See the Profile for buddycraiggClick Here to Email buddycraiggSend a Private Message to buddycraiggEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 72and86:

With the IAC removed the car starts and runs 1000 RPMS for about 8 seconds and dies.


There is a problem with that. It should have had a very high idle. Probably higher than 3000.

There are 2 fuses for the injectors on the V6. Each row has its own fuse. Check both of the fuses. If one of them is blown, then only one bank will spray.
I'm also curious to see what your fuel pressure is when it is trying to run after you get your gauge.

[This message has been edited by buddycraigg (edited 10-10-2021).]

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Rexgirl
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Report this Post10-10-2021 04:49 PM Click Here to See the Profile for RexgirlSend a Private Message to RexgirlEdit/Delete MessageReply w/QuoteDirect Link to This Post
As I understood, the tube I indicated supplies air to the cold start injector, so if it leaked a lean condition would happen. But maybe that was incorrect?
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Patrick
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Report this Post10-10-2021 05:22 PM Click Here to See the Profile for PatrickClick Here to Email PatrickSend a Private Message to PatrickEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Rexgirl:

As I understood, the tube I indicated supplies air to the cold start injector, so if it leaked a lean condition would happen. But maybe that was incorrect?


I've never heard it described as being there for that particular purpose.

As I understand it, air entering the indicated IAC port below is metered by the IAC valve and then passed through the tube at the back of the TB and into the intake plenum.



 
quote
Originally posted by Patrick:

"Cold start tube"? Doesn't that tube supply air that's been controlled/regulated by the IAC valve?

[This message has been edited by Patrick (edited 10-10-2021).]

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72and86
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Report this Post10-11-2021 10:46 AM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by buddycraigg:


There is a problem with that. It should have had a very high idle. Probably higher than 3000.

There are 2 fuses for the injectors on the V6. Each row has its own fuse. Check both of the fuses. If one of them is blown, then only one bank will spray.
I'm also curious to see what your fuel pressure is when it is trying to run after you get your gauge.



Yeah it was probably closer to 3000 RPM, not 1000. I will check those fuses if I can find them.
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72and86
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Report this Post10-11-2021 12:46 PM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by buddycraigg:


There is a problem with that. It should have had a very high idle. Probably higher than 3000.

There are 2 fuses for the injectors on the V6. Each row has its own fuse. Check both of the fuses. If one of them is blown, then only one bank will spray.
I'm also curious to see what your fuel pressure is when it is trying to run after you get your gauge.



Pulled fuses and they all check out with multimeter. They are fine.
Next?
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buddycraigg
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Report this Post10-11-2021 09:58 PM Click Here to See the Profile for buddycraiggClick Here to Email buddycraiggSend a Private Message to buddycraiggEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
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Originally posted by 72and86:


Yeah it was probably closer to 3000 RPM, not 1000. I will check those fuses if I can find them.


Well then you gave me bad information the first time.
So did it really idle around 3000 with the IAC removed?

I think you said you have a fuel pressure gauge on order.
The next thing I want to see is how the fuel pressure responds while it is running/stalling.
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72and86
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Report this Post10-12-2021 10:48 AM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by buddycraigg:


Well then you gave me bad information the first time.
So did it really idle around 3000 with the IAC removed?

I think you said you have a fuel pressure gauge on order.
The next thing I want to see is how the fuel pressure responds while it is running/stalling.


Well its hard to remember all the combinations we tried to get this car running, must be 50 or more things we tried.

Its important to understand it doesn't idle, it SURGES to an RPM, in this case roughly 3000 then dies. Run time is only a few seconds. BUT If i keep pumping the gas pedal it will continue to run but very choppy and Im really "on the pedal". I let off, it dies.

Also this car was purchased last year as not running. We got it running by new distributor/coil parts, but idle was always choppy and high. It only has been yard driven cause I dont trust it. It has never seen under 1300RPM at idle when it ran. I thought it was the inherant problem with the TACH computer board. But even then when I drove it around the block it had a bad low end dead spot, no power.

Yup Fuel Gauge on order.
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buddycraigg
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Report this Post10-12-2021 09:22 PM Click Here to See the Profile for buddycraiggClick Here to Email buddycraiggSend a Private Message to buddycraiggEdit/Delete MessageReply w/QuoteDirect Link to This Post
Just so you know, I wasn't bashing you.
I was letting you know that we need accurate answers when we ask question, or it could throw us off with what we think is going on.
Waiting to hear what your pressure is when you get your gauge.
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72and86
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Report this Post10-12-2021 11:41 PM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by buddycraigg:

Just so you know, I wasn't bashing you.
I was letting you know that we need accurate answers when we ask question, or it could throw us off with what we think is going on.
Waiting to hear what your pressure is when you get your gauge.


Ok well the gauge arrived and we tested it. This is the V6 engine.
Key on position : 5 psi,
Key starts car and constantly pumping the gas to keep it going; 15 psi. Obviously very low. We know gauge is reading right cause we put the line into a bottle and turned the key on and had a very low stream.

So its hard to believe we replaced a weak pump with a NEW weak pump. Needless to say we dropped the tank and I ordered a new fuel pump. Also checked the fuel filter, it was fine. Is there a way to accurately test the pumps before installing them. I know I can get it to run but...?
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Report this Post10-13-2021 12:15 AM Click Here to See the Profile for skywurzClick Here to visit skywurz's HomePageSend a Private Message to skywurzEdit/Delete MessageReply w/QuoteDirect Link to This Post
That sounds like you got a L4 pump not a v6 pump
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buddycraigg
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Report this Post10-17-2021 02:42 AM Click Here to See the Profile for buddycraiggClick Here to Email buddycraiggSend a Private Message to buddycraiggEdit/Delete MessageReply w/QuoteDirect Link to This Post
I have to agree that you have very low fuel pressure. I think the V6 is supposed to be about 35.
Could be the wrong pump.
Could be a bad fuel pressure regulator. (I don't think I have ever seen one go bad)

[This message has been edited by buddycraigg (edited 10-17-2021).]

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buddycraigg
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Report this Post10-17-2021 02:54 AM Click Here to See the Profile for buddycraiggClick Here to Email buddycraiggSend a Private Message to buddycraiggEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by 72and86:
We know gauge is reading right cause we put the line into a bottle and turned the key on and had a very low stream.


I don't like this statement.
both the 4 and 6 pumps move a lot of volume. it has nothing to do with pressure.
We might be fighting a restriction somewhere.
I'm not thinking that right now, but want to keep it in the back of our minds.
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72and86
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Report this Post10-17-2021 11:18 AM Click Here to See the Profile for 72and86Click Here to Email 72and86Send a Private Message to 72and86Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by buddycraigg:


I don't like this statement.
both the 4 and 6 pumps move a lot of volume. it has nothing to do with pressure.
We might be fighting a restriction somewhere.
I'm not thinking that right now, but want to keep it in the back of our minds.


We will see. I definitely got the wrong pump. Hopefully I get the pump Monday, install Tuesday...
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