91 Ragtop

I am far from mechanically inclined but also don't want to throw money at repairs especially expensive ones!

I've got an intermittent problem with the car continuously running. I've recently went on a 60 mile trip and the car just quit running.. like it ran out of gas. I pulled to the side of the road and it wouldn't start back up. It would turn over, sputter for a few seconds and then quit again. I assumed at this point my fuel pump quit. 30 minutes later, I tried to start the car one more time before calling a tow truck... and bam.. Started right up. No problems on the 20 mile trip home from that point. Drove it around and didn't seem to have any real problems except some intermittent hesitations on accelleration. I went to the Tipp City Trans Am Nationals cruise in and the same thing happened. Fortunately I was parking when this happened this time though. Car stalled on me and I couldn't get it started. I stayed there for a good 4 hours. Started the car for the trip home no problems and drove the 90 miles back.

Last weekend I put a fuel pressure gage on the car and routed it to my windshield so I could see the pressure and took a 60 mile drive around Columbus. This is what it showed:

42 PSI at initial pressurization.
36-38 PSI while cruising at set speed
34 PSI when slowing down via brake and downshifting.
Between 42-50 PSI at wide open throttle.

It did stall on me one time after this long drive while waiting in line at a drive through. THre pressure showed 20 PSI before I tried to restart it. This time it started right up though.

Things I did notice were a high pitched whine coming from the fuel pump when I did restart it that time. I noticed this whine in Dayton also.

The guage seems to bounce around alot between the 38 and 42 while driving around. It did alot of bouncing, no consistant pressure except for slowing down.

I searched the forum and didn't find answers specific to my situation. Any ideas??

Thanks for the help.!!!

CamaroRider

You could be having a problem with the 'fuel pressure regulator'. During those times your fuel pump might be really working hard to get the pressure up to the typical 38 PSI range and hold it there.

Also, to mention another possibility, there is a submersed rubber 'connecting hose' in your fuel tank that connects the fuel pump to the hard line that eventually exits the fuel tank. If that is developing a 'split' it could allow fuel to exit right back into the tank and thus reduce your fuel pressure.

Maybe you have excess vacuum building up inside your fuel tank and causing fuel feed problems. You could try loosening the gas cap when you have a problem and see if the car then starts immediately.

So these three things could make you THINK it is the fuel pump 'motor' yet not be the motor itself.

91 Ragtop

It doesn't seem like it's having any problem getting to the 42 PSI although it doesn't do it the 1st time I turn it to on, but will be there on the 2nd. The service manual gives me the impression that it is normal though.

A couple more observations I had when I took it for a nice drive tonight.

1st. The guage WAS NOT jumpy like it had been the last couple days. It stayed still and moved between 34 PSI when slowing and 40 PSI at steady cruising. Ran great tonight.

The only difference I can think of is the weather. The temps were in the 90's and humid when it did quit working or the guage was bouncing around. Tonight it was in the low 70's and cool.

I'm going to drive it with the guage hooked up for the next week and see if I notice any other oddities with it. Although I'm going to have to do it when there is 0% chance of rain... the guage is currently wiretied to my wiper so I can see it while driving.

CamaroRider

Typically when your engine is shut off the fuel pressure should HOLD at the pressure it was at just before the engine stopped. It should stay pretty much at that pressure for about 20 minutes or longer. The 'weep holes' built into the system will gradually allow that pressure to bleed out over time but in the short run that pressure should hold.

There is a one way valve in the fuel pump, a pressure regulator and injectors, submersed flexible hose in the fuel tank. These are items that could cause high pressure loss without being too obvious to the driver.

Keep an eye on that fuel pressure especially when the engine stops or is shut off. If you see a low fuel pressure displayed at any of those times then I would say you have the symptom of an occurring problem identified.

If you shut the engine off on purpose and the pressure holds and you find that when the engine quits on its own the fuel pressure does not hold, then you should probably make one change and monitor the system again.

And keep an ear on the sound of the pump to see if it becomes abnormal like you described above. If you can tie that consistently to the same time the engine acts up then that would be of interest.

You mentioned that the fuel pump seemed to be or was making a louder than normal high speed whine two different times when you had problems. In my experience with my fuel pump I heard the pump sound that way when it was not submersed in enough fuel. This was remedied when I added 5 gallons to the nearly empty tank. But it also sounded rather loud when the fuel line was empty and the pump had to prime the fuel line. When the fuel pump is working with a full fuel line and there is enough fuel surrounding the pump so that it is not 'starved' the sound is quite muted.

navyCM

iTrader: (3)

could be your fuel pump relay. i had a similiar problem and the relay was the cause.

91 Ragtop

Actually I already did that. Unfortuately it didn't solve it. I drove it today again and no problems. I'm starting to wonder if the heat is affecting it?? The guage was steady.. no bouncing around. I had fuel pump problems with my Corvette last year and the relay seemed to fix it. Except in my Vette's case, it just quit running and wouldn't start again. I wish that would have been the case with the TA. Makes fixing things a lot easier. LOL

navyCM

iTrader: (3)

did you fill up just b4 this issue started? could have just been bad gas.

Elthesh

The fuel pump could very well be your problem. Mine recently died and was giving out the following symptoms.

At the end, it sounded like a dying cow when it first primes. For a few weeks or so prior to it's death, it would cause random hesitation on acceleration, caused the SES light to come on, giving a false O2 sensor code, and stalled out while driving down the road occasionally. Until the very last day, it would always restart, and on the last day, it barely restart and ran like it was getting very little fuel, which of course was the problem. Finally after getting it in the lot, it would turn over and not start, finally getting it started after waiting about 10 minutes or so, it managed to hobble over to a parking spot, barely, and almost not making it over a speed bump. I had a nice flatbed come over after that to give the sick car a ride to the dealer for a new fuel pump, relay, and a few other items including the fuel pressure sender. Essentially the entire lock stock and barrel from those metal pipes going in the tank to the strainer at the end was replaced. No need to put on some 17 year old part to have it break in a year and have to yank the tank back out again.

Also, the fuel pressure was reading about 20psi before the pump was removed.

TexasSilhouette

iTrader: (4)

This is what the Walbro pumps frequently do when they fail.

WicketMike

I searched and found this thread. I seem to be having the exact same problem.

It starts up the first time, i pull it out of the garage and park it in the driveway and want to start again right away and it wont start. Let it sit for about 15 mins and it starts right up.

yesterday i was driving and went WOT and the car shutoff, i coasted to a stop. wasnt sure what was wrong so started pushing it. was about 1/2 mile from home. got tired. Let it sit for 20 mins and it started up but it was sputtering and i had to baby the gas pedal to move it at 5mph, then all of a sudden it acted like nothing was wrong and i sped home and parked it in the garage.

If i find something ill post it and ill be watching if you find something

thanks

scramblin

I have the same problem. Let me know if you fix it. New injectors are going in the car tomorrow.

derekiroc

I have the same issue with my IROC. I have replaced the fuel pump 3 times and now looks like the 4th pump is on its way out. I hear the sound of pump death (Whinning or Humming) and the engine sputters at low throttle and even cuts out. I purchased the pumps from NAPA who has replaced everyone for Free but its getting old. Wed, plan to replace with stock GM pump. Does anyone heard of Bosch injectors killing fuel pumps since the orfice design is smaller, in effect increasing fuel rail pressure?

Roastedchicken

OK Im having a similar problem right now in fact today at lunch my car wouldnt start . . I have typically been able to let the car sit for 45 seconds or so and turn the key ,cycle the pump , and the car will start but today it decided not to . SOOOO it went on a tow truck to the shop. The guy that will b working on the car told of the possibilities. Number 1 Fuel pump is not holding enough pressure. He said anything under 38 pounds is not enough if the injectors arent in perfect shape( which mine arent 210,000 miles). Number 2 computer could be the problem caused by the crank sensor not giving a signal (which could cause no reading to injectors). And number 3 and improbable (he says) could be injectors arent reading enough resistance or something like that. He told me i will know by tomorrow. So when i find out ill let you guys know and hopefully it help your endevours.

WicketMike

hey Roasted,

any news yet?

thanks!

Roastedchicken

Sorry it took me so long to get back. OK Here we go. Mechanic told me EASY fix( yak) He told me it was my ignition module , ignition switch and idle air con trol valve. Ignition switch had a hole burned in the side, module wsa failing and iac was stripped out. So i said fix it. Called and told me come get it, so off i went . Just before i pull in their drive he calls again. Its still broke. Come to find out 3 of 8 injectors are way bad, 2 are sorta bad the other 3 are great. Ignition module was fine. switch was still so i kept it. The kicker is it cost me 447.00 dollars to have my car not fixed by him, reason being is he wanted 1800.00 and some change to replace 5 of the 8 injectors. After i got done vomiting i bought my own and replaced all.Easier than i thought.
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All in all , it cost me 346.00 to replace all injectors and it runs like a champ now. Took me about 6 hours on saturday and i learned alot. Wouldnt hesitate to do it again so if anyone needs injectors done im available. LOL

thegooseman

I had similar symptoms to you guys and it ended up being my ignition module, and not the fuel pump.

devilish1

Had a similar problems last summer. Changed the pump without any issues since.