So I decided to make a separate topic from the pickup coil one since it is looking like the issue with my car has more to do with the fuel pressure than the ignition system which by this point has all but been completely replaced.
So stopped and picked up a fuel pressure tester yesterday. Got home and hooked it up and found the following: Engine off / ignition on - a whopping 16 PSI wow! After finally getting it to run the max pressure was 24 PSI.
So what do we think is the problem? I would think fuel pump since I just replaced the fuel filter last weekend and there was fuel coming from both sides of the filter. Any thoughts on what brand of fuel pump I should go with?
Probably the little black hose in the tank that connects the pump to the sending unit deteriorated. A new pump will come with one, and if the hose rotted away, the pump isn't far behind. Definitely get an AC Delco fuel pump.
If it's a Duke then your pressure is way high. If it's a V6 then too low. (Can't tell your engine type as China blocks links to pics) Stock daily driver? RockAuto has OE Delphi pumps for $60 plus shipping. Don't forget a new strainer.
If it's a Duke then your pressure is way high. If it's a V6 then too low. (Can't tell your engine type as China blocks links to pics) Stock daily driver? RockAuto has OE Delphi pumps for $60 plus shipping. Don't forget a new strainer.
Sorry that is also my bad for not putting that it is an 87 GT 2.8l V6 in the original post here. I am buying the strainer from RockAuto but Amazon actually has the same AC Delco fuel pump for $54.02 and since I am an Amazon Prime member I get free two day shipping so that looks like my best deal. Funny just seems like I want to order something from RockAuto to see what is on the fridge magnet they usually pack in with the parts.
[This message has been edited by FieroJam (edited 05-18-2012).]
With low fuel pressure there is one more thing that could cause the problem. Before condemning the pump you should really run the proper GM fuel pressure test. Pinch the fuel return line and then activate the pump. If the pressure is normal then the fuel pressure regulator is bad. If it’s still low then it’s the pump (or feed line on the pump output).
With low fuel pressure there is one more thing that could cause the problem. Before condemning the pump you should really run the proper GM fuel pressure test. Pinch the fuel return line and then activate the pump. If the pressure is normal then the fuel pressure regulator is bad. If it’s still low then it’s the pump (or feed line on the pump output).
I second this. Since the regulator just blocks off the return line until the pressure is reached, if it is stuck open, or has a similar problem which causes fuel to flow through it easier, your pressure will be quite low! And since fuel pressure KOEO is just primed, and KOER is fuel pump running all the time, I would lean to regulator instead of pump, so definately worth the test! If you lack hose pliers to clamp the return hose, one method I used before works well: Cardboard (like a thin box, not dual layer) folded a couple times, then around the hose, and then use flat vice grips to pinch it. The cardboard will protect the hose from the vice grip's teeth, and the vice grip applies the pressure to collapse it.
Where ever you can get to the rubber line to pinch it. Either by the tank of behind the engine along the firewall. If you use a visegrip or the like cover the jaws with some pieces of hose (or similar) to keep from damaging the line.
SO I replaced the fuel pump today with the help of a friend and the car will now start up on the first try and run just fine. But when I just now tested the fuel pressure again it is now going up to 40psi when the key is turned to start and you hear the fuel pump running. But as soon as the pump stops running the pressure starts to drop down to almost nothing again.
Lovely update on my car is that when I went out to leave for work this morning when I turned the ignition on and heard a really loud vibrating sound from the fuel pump as it primed. Car started on the first try and the loud sound was not present anymore. Got no more than a few blocks from my house and the loud vibrating sound started again along with the car stumbling and staling. Got it back home and took my wife's car to work. WTF? Could the fuel pump have come loose somehow? Will be dropping the tank again tomorrow to see what is going on. Still wondering about the pressure readings I got yesterday after we swapped the pump.
Typically when you get a new pump it includes a short piece of hose to replace the pulsator with. Remove the pulsator, insert and clamp hose on both ends.
Typically when you get a new pump it includes a short piece of hose to replace the pulsator with. Remove the pulsator, insert and clamp hose on both ends.
I was wondering what that hose was suppose to be for. Thanks
Dropped the tank again today and removed the pulsator and replaced it with the hose and hose clamps that came with the new fuel pump. After getting it back together the pressure is back up to 42 and holds. Don't want to do that again for a good long while.
Just over a year later and yet again fuel pressure issues. And again seems like it is the fuel pump. After my 87 GT died on me at a stop light in Tampa on the way home from work and I had it towed back I got to check the fuel pressure and it goes up to 40 psi and rapidly drops to 20 then pretty much nothing. So I went and got some hose clamps to pinch off the return line and try it again. Well the results of that is that the pressure jumps up to almost 70 psi when the fuel pump primes but then again drops off to nothing again real quickly. So I guess its time to drop the tank again tomorrow kind of hoping its a line issue in the tank and not the pump but we will see.
Originally posted by FieroJam: Dropped the tank again today and removed the pulsator and replaced it with the hose and hose clamps that came with the new fuel pump.
Likely intank hose is rotten... special hose (SAE J30R9) in the tank that likes Ethanol etc.
------------------ Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should. (Jurassic Park)
The good question is will the monkeys at Autozanny or AdvancedParts barn know what I'm talking about when I ask them for some SAE J30R9 hose?
quote
Originally posted by theogre:
Because you [QUOTE]Originally posted by FieroJam: Dropped the tank again today and removed the pulsator and replaced it with the hose and hose clamps that came with the new fuel pump.
Likely intank hose is rotten... special hose (SAE J30R9) in the tank that likes Ethanol etc.
Actually there was nothing wrong with the hose used to attach the fuel pump. After changing the fuel pump the pressure will hold steady after priming. And the car ran fine for the rest of Saturday and part of Sunday morning but all of a sudden the car just died on me again while doing some shopping. It would not start up but the fuel pressure was going to 40-45 psi after priming and only dropped about 2-3 psi after 10-15 minutes. So know the question is what is making it shut off out of no where?
I'm new to this forum, but not Fieros, having worked on my buddy's 85 since new, until it burned up after being sold. After a long hiatus, last year, I bought an 87 GT 2.8L with supposedly 70K miles. All was good until one morning it wouldn't start. I determined without a doubt it's a fuel problem, but I'm at my wits end trying to figure out what the cause is. This forum has been very informative and I tried just about everything I've read, with no success. I replaced the fuel pump twice, regulator, and pulsator, but the most I can make the car do is idle sometimes, and any hint of throttle makes it die. Other times it won't even start.
I get about 40lbs of pressure going into the fuel filter, which when it runs, is at about 38lbs until I open the throttle a bit, and it drops slightly before dieing. The pressure drops off fairly quickly with the key off, dropping to under 20 lbs in less than 10 min. I disconnected the return line and plugged it, and when I got the car to start, it got up to over 90 lbs before I quickly shut it off, for fear something would blow. I still wasn't idling properly though.
It dropped from 90psi gradually and hung at 60 indefinitely, seeming to imply the regulator is what is bleeding off the pressure quickly when the line is not plugged. It certainly doesn't seem the injectors or pump are responsible for any appreciable leak, but I already replaced the regulator, and the original looked fine. And as I said, the pump has been replaced twice.
My SES light is not on, but grasping at straws, I jumped it to see if there were any codes, and indeed 33 and 34 came up. Both appear to be related to MAP sensor issues, but I haven't seen anyone talking about the MAP sensor, in relation to fuel problems. I did just read another informative thread here about a MAP problem, that had some similar symptoms, so maybe I should be going after that, per the instructions in the other thread? I just wondering if some other fuel problem is causing the MAP codes to come up.
I see in some discussions mention of the ECM as well, but in this thread, no mention at all. Should I be looking for ECM issues, investigate the MAP, or buy a large bottle of whiskey and drink my problems away?
I like the whiskey idea!!! Map sensors will cause fuel issues. If you have live data on your scan tool...ck to see if the map sensor is reading. If it stays at a certian value, usually around 4.5 volts. Then you should try another known good map sensor. Also take a good look at the vaccum lines. Make sure the elbows are not cracked or rotted away. Have seen this cause many driveability issues. Best of luck. Hope this helps Brian
[This message has been edited by bkw88 (edited 08-24-2015).]
Welcome to the Forum! You should electrically unplug the MAP and start the car. The computer has some default settings. Perhaps it will run, but if it does not, the ECM is a suspect too.
edit: The whiskey option has this problem of being temporary......so I would concentrate on the MAP and ECM.
[This message has been edited by Gall757 (edited 08-24-2015).]
Here's the latest, though not exactly inspiring confidence yet.
I replaced the MAP sensor, and same as has been the case recently, I couldn't even get it started. I checked the 5V and ground pins and sure enough 4.99V so no obvious issue there. In desperation I was going to order another ECM, because that's the only damned thing short of injectors and vacuum lines I haven't replaced. I replaced the filter BTW, though I neglected to mention that earlier.
In my attempts, it was doing the usual trying to start, with rich smoke out the exhaust. I pulled the easy 3 plugs in the back thinking maybe it was old school flooded, and while moist, not otherwise unusual, but I gave them a quick clean. Good for nothing, as expected, on the next attempt.
Now I'm at the point of retracing my steps, confirming it would at least start with starting fluid. Don't know if it's the magic of an 11 year old girl, or what, but I had my daughter turn it over while I shot fluid in the throttle body, and it not only immediately lit off, it kept running. It ran at about 2K for several minutes and finally settled down to the usual 900rpm.
I haven't yet buttoned everything up and taken it out on the road, but I can rev the bejeezus out of it now and it won't cough and die. I do notice however, as mentioned elsewhere in this forum, it will hesitate if I romp on it too hard and quick off idle. It may have done that before though, I don't know, as that's not the way I would normally drive. Swapping MAP sensors made no difference, so not sure what that is, but for the moment, she's alive again, and we'll see how she does under load on a test drive.
I know this makes no sense, but when I first replaced the fuel pump I had no clue about the pulsator issues, and I found it strange you just slipped the pump and fuel line into this this thing with no clamps, and expected it to work at 40PSI. Given I simply reused the pulsator, I was sure that was my issue, but it seemed like the car (ECM) remembered being more and more sick, and wouldn't respond to fixes, like my replacing the pulsator with a chunk of hose. The defibrillator (starting fluid), sparked it back to life enough to reassess it's health and decide maybe it was OK again, after the surgery performed while it was seemingly in a coma.
I'll let you know how she fares after the road trip, but thanks for the advice in the meantime.
...it seemed like the car (ECM) remembered being more and more sick, and wouldn't respond to fixes, like my replacing the pulsator with a chunk of hose.
As long as you disconnected the battery while you were doing all the repairs... which you sure as heck better have, your ECM remembered nothing.
The saga continues. Got it all buttoned up Sunday, took it for a spin, and a few blocks away I come to a stop sign, and it dies as I attempt to accelerate from the stop. It won't start until I hit it with the starting fluid again, after which I drove a few more blocks revving the heck of if with no issue. I didn't trust it though and brought it back home, where moving it in the driveway later proved to be too much for it again, requiring starting fluid to revive it.
The engine light is not on, and the 33 and 34 codes were not present when I got home.
This is possibly the most frustrating automotive problem I've ever had. I've finally ordered another ECM, as I'm out of things to swap. And when it runs, there is plenty of vacuum at the MAP, so there is no reason to believe there is a vacuum leak. I also inspected the lines when I had the plenum off, and was replacing the regulator.
I'll let you know how it goes, but if you hear of a car fire, it may be me throwing in the towel.
What brand of fuel pump have you been using? I"ve used Bosch pumps in 3 cars, and no problems with any of them. If you have good pressure when running, and it goes down quickly after you shut down, there has to be a leak somewhere. Is your pressure regulator still the original?
The first one was a Delphi from O'Reilly's, and the second an Airtex from NAPA. And, as I indicated, the Delphi went to 90 PSI when I completely blocked off the return line, and dropped slowly from there to 60PSI, where it sat for 30 min before I released it. That would seem to imply the regulator is the source of my bleed off, but I'm not sure how much that's contributing to my problem, and I replaced it anyway, with the old one looking just fine.
Before all of this, the car would start unusually quick when cold, like in a second, and require 2-3 seconds when hot. Now it never starts in less than 2-3 seconds, even when I had the return line completely blocked, which I assume takes the regulator out of the equation.
We'll see what the ECM brings, but I can't see getting yet another fuel pump, even though I can drop that tank in my sleep now. Thank God I have a lift.
When the car starts more quickly when cold than when hot, that is (I think) an indication that the cold start injector is working correctly. Maybe now it isn't.
Had a nice brisk walk this afternoon. No, not because I was looking for some exercise, because my POS left me stranded and I had to walk home. Here's the latest. I put the refurbed ECM in, and it fired up, albeit only after a few seconds, versus my seemingly forever gone cold "instant start". I took it for a run with my son, so if it died one could start while the other force fed some starting fluid.
I drove it probably 5 miles, playing with an obvious hesitation to take too much throttle quickly at low rpm, much like a carbureted car in the cold with no choke. I thought maybe it would learn it's way out of it, so I kept testing it, letting it run at low rpm in any gear, then rolling on the accelerator quickly. It would consistently hesitate, but then catch itself after a cough or two, and move on, driving fine.
Finally, I rolled on the accelerator more quickly at low RPM, and it did the chitty chitty bang bang thing worse than ever, wasn't able to recover, and died. And that's where it presently sits, with no amount of nursing with starting fluid, partial throttle, no throttle, no fluid, or anything else able to yield more than it firing once in a while, acting like it's going to start, but doesn't.
I'm so frustrated, once I get it home, it's going in the back of the garage, where it can sit and rot, until I get a helluvalot of other things done, versus spinning my wheels on this POS . I've changed every component in the system once, if not twice, to of no avail: Pump twice, filter once, MAP twice, regulator once, ECM once. Next time you hear from me, it will likely be in the "for sale" section.
Looking for input on a different fuel supply strategy, given my Fiero has now resigned itself to not even hinting at starting.
I have a 73 Mach 1 I have installed an LS2 in. After months of troubleshooting a lack of pulse to the fuel injectors, I finally got someone well versed in tuning to program my ECM properly, got the pulse, and wham, it fired up yesterday, running like a dream.
The reason I bring that up is my fuel supply to the LS, is much simpler than the Fiero, with a filter/regulator from a Corvette, which requires no electronics or vacuum. I'm sure the MAP and MAF are being used to control injector pulse width, etc., but at least the supply is simpler.
I have a gauge on the fuel rail feed, and it runs around 58psi, and stays there well after key off. Currently, my "gas tank" is a 5 gallon bucket, with Walbro 340 in tank pump feeding my filter regulator, and from there to the rails. As such, it's quite portable, and I'm wondering if I couldn't at least test my Fiero supply system by substituting this to the fuel rails. I'd block the return line to the existing Fiero tank off
I know the Fiero is supposed to run around 40 psi, but as I noted earlier, when I completely blocked off the return line, it soared to 90 psi, and didn't blow anything up. As such, I'm thinking the system, including injectors, could probably handle 58 psi at least for a while. When I blocked of the return before, and turned the car off, it slowly dropped from 90 psi, until it reached 60 psi, where it seemingly could have remained for hours.
If it worked, I'd love to entertain the thought of changing the system permanently.
The Fiero 15 Lb. injectors are rated that way assuming a 40 Lb. supply line. By doubling the pressure you will nearly double the output of fuel. If your car runs at all, the exhaust should be black as coal.
The computer has some capability of modifying the fuel mix based on readings from the 02 sensor, but I suspect even a 58 Lb. feed line will be too much to correct. Does the tach move up to about 300 rpm when you try to start the car?
[This message has been edited by Gall757 (edited 09-11-2015).]
I didn't have time to hook up my LS set-up today, but rechecking the fuel pressure into the filter, it was 40 psi, and actually held decently dropping only to 35, after about 5 min.
When cranking it over, the tach will read 400 RPM. I assume the reason for asking was to get a read on whether or not the ECM was detecting revolutions and spark, but I certainly welcome all input.
Try replacing the fuel pump relay. Had an 85 gt that would not start after driving it then parking then trying to start it again. Car would start back up in about 20 min. My father was the service Mgr at the dealership where I bought the car new. It was a malfunctioning relay that would get hot and would not complete the circuit and sometimes would not close when you turned the car off drawing down the battery which exacerbates the electrical relay. Car was only 2 years old at that time. It's worth a shot.
