Johnstonxj

I hope this is the right place to post this question, and sorry if it's already been covered...

I drove my 1988 GTA to work (~7 miles) yesterday morning and it ran fine as per usual. When I went to leave at the end of the day, I turned my key and it fired right up, but only for a few seconds before dying out. So I tried again, and the same thing. I tried again, but this time while giving it some gas, and the same thing; the RPMs just drop off and it dies.

So I reluctantly let it sit in the parking lot over night and bummed a ride home. This morning I got to work and decided to try and fire it up again. I turned the key and it fired right up like normal. Didn't skip a beat and ran well.

I'm worried though that something related to my ignition, fuel delivery, etc is about to give out on me for good. I'd like to be proactive and try to fix the issue now if possible. The same thing happened to my old Jeep and it ended up being the fuel pressure regulator. Could that be the cause here as well, or a flurry of other issues? I have a new ignition coil, fairly new injectors, newer plugs and wires, new distributor, and EGR. I'm not a professional gear head by any means but any ideas are helpful.

Thanks!

Bob88GTA

iTrader: (2)

I would have to go with the fuel pump. Mine acted similar before it went....1 day notice, and then that was it. Changed pump and all was well.

Johnstonxj

I'll look into it then. I can hear it priming, but you never know. It is 30 years old...

Johnstonxj

To follow up on this, I think you're right. I went to try and start the car today at lunch in the hot sun, and the pump was not priming. I ordered a new fuel pump and will have it put in and go from there.

Bob88GTA

iTrader: (2)

Good deal! Thanks for the update. Are ya dropping the rear for the install??? Head nodding yes I see! Good!

Johnstonxj

Haha. It's reallllly tempting to just cut through the uni-body, but I'd rather have it done right and not catch the thing on fire. I'll most likely be having a guy I know down the road drop it and replace it for me. Unfortunately I don't have the proper means/time currently of getting this done in my garage at home.

Bob88GTA

iTrader: (2)

Gotcha, good luck with it. It's not a bad job when you have the space and tools. Me and a buddy completed mine in 5 hours...with breaks.

Johnstonxj

Not bad. I'm hoping to at least be able to get it home when the temp cools off tonight or early morning, just to get it out of the work parking lot a few minutes from home. If I can get it back to my garage and out of the weather I'll be happy until my new pump arrives next week. I keep telling myself "well, it needs inspected anyway... 2 birds, 1 possibly expensive stone."

dagwood

iTrader: (5)

I had an 88 GTA that acted the same way a few times and it was.....ahhhhh what did they call it.....the idle speed motor??? or idle speed sensor??

if you can't hear the fuel pump though, that's probably it

Pro

Smack the gas tank a few times to get it turning on again. Then use that time that it's on to pump out the rest of the gas in the tank so that you arent lowering 100lbs. Assuming you decide to do it yourself.

GTA88

Johnstonxj, any update? Was it the pump? Something else?

What kind of pump did you get?

How much did the mechanic charge for the install, if done?


I may be transferring funds to a mechanic soon for the same thing on my 88 GTA.

Johnstonxj

Well I have a small update. Nothing fixed yet. It seems the holiday weekend has got the mechanic I want to use all backed up. Although I am a bit irritated. I was supposed to have the car towed last week and that hasn't even happened yet... Hopefully it happens today.

Anyway I just got back inside from lunch. It's in the low 60s today outside. The car actually started and idled fine for about ~25 or so minutes while I sat outside on lunch break. I let it sit a while, and then I shifted it into reverse. When I put it in R, the RPMs dropped to almost nothing but it seemed to catch back up to itself and level off around 500-600 RPM in reverse. Same with when put into drive. Odd...

Would the 80+ degree heat from the prior weeks cause the fuel pump to act up? Still doesn't quite explain the car almost dying when put in to drive or reverse today though. However I will check into the idle speed sensor.

Johnstonxj

Do you mean perhaps the Idle Air Control?

Johnstonxj

Got the car towed today to another mechanic so we'll see what they find out soon hopefully.

GTA88

Johnstonxj,

Any news ???

Johnstonxj

No news yet. Waiting on a call from the garage. Hoping today so I can have it for the weekend, but I won't get myself too excited. I'll let you all know what they find when I do go get it.

dagwood

iTrader: (5)

That's probably it...thanks. I knew it was idle somethingorother.

GTA88

I keep checking here to see if Johnstonxj has an update for us. Guess I'm just impatient.

Then I remember I once had my GTA towed to a mechanic for a rough-running engine problem, and the guy had it for 2 weeks before he fixed it. lol.

Johnstonxj

I'm still impatiently waiting myself. It's killing me. Luckily the weather hasn't been the best for driving as of late. However there have been a few perfect evenings here that really had me pacing the floor. I'd expect to hear something this week. Tomorrow will have been a week since it got towed I believe.

If my first mechanic didn't leave me hanging, I could probably have had this issue sorted out already...

Johnstonxj

Just got my car back. It's running surprisingly better than it has in a while at the expense of my checking account lol.

The garage replaced my fuel pump of course. They said the pressure was low at the rails. I forget what they were getting as far as pressure exactly (Low 20s), but it was below normal. After they got that all taken care of and replaced, it was still having trouble staying running. So they did more tests. Turns out, my MAF also went bad.

So it was sort of a combo of 2 issues I guess. The fuel pump wasn't totally shot, but it was getting there. I don't drive the car a ton so the problems would have probably shown up sooner than they did had that been the case. I have also noticed in past years the car stalling out at stop lights and what not from time to time. That was probably an early sign of the MAF going. I can definitely notice the big difference though now, and I'm happy to have it back. Like I said above, it is running as good as that old 305 can as far as I'm concerned.

GTA88

Thanks for the update. Glad the car is in good shape again.

Interesting that your fuel pressure was down to low 20's.

The psi in my GTA is only 26. I questioned 3 mechanics around here about whether my bucking and hesitation might be caused by 26 psi and 1 said yes, one said maybe and the third one said the psi can get as low as 10 without symptoms!

I probably should have my fuel pump replaced anyway since 26 is way lower than 39 (which is what it is supposed to be).

Today I plan to check out the passenger side spark plugs for fouling, thinking an injector might be sticking open or closed, causing the intermittent hesitation and bogging.

May I ask how much they charged for the fuel pump install? Do you know what brand of pump?

GTA88

Johnstonxj

I bought the pump for ~$20 on Rock Auto. It's a Bosch. They purchased a new MAF for me which I know those aren't cheap. For the entire job (dropping the rear and tank for the pump, and MAF replacement, plus all the testing they had to do PLUS putting it all back together and inspection) it was around $680. This mechanic does fantastic work. Probably the best in the area, so I was actually expecting it to be more.

I was having stuttering issues last year, and it ended up being my spark plugs. Changed those and the problem went away immediately. I also had new fuel injectors put in about 2 years ago from Fuel Injector Connection. Well... refurbished, but good as new.

armos

The mechanic who said it could go down to 10 must have been thinking of TBI, not MPFI/TPI. But if the pressure is low but manages to still be consistent, the symptoms might not be as bad.


If the fuel pressure doesn't stay consistent with respect to the air pressure in the manifold, the flow rate of the injectors will be inconsistent and the ECM will have fits trying to get the fuel right.
If you jump on the throttle under load, the manifold air pressure will increase, and if the fuel pressure doesn't increase accordingly then it might cause a stumble. That could happen due to a weak fuel pump, bad fuel pressure regulator, or the vacuum reference hose to the FPR isn't connected, leaks, or plugged. Maybe some restriction in the fuel line, if the car has sat enough for that to be a possibility.

If you use a vacuum gauge to watch the manifold pressure, and watch a fuel pressure gauge at the same time, they should track together.

You could try keeping a gauge connected while you put a load on the engine or even drive it. Expect to see the pressure fluctuate within a few psi along with changes in the manifold air pressure. But if you see it drop off very much under load then the pump is probably failing to keep up with demand. When accelerating at WOT the fuel pressure should be nearly the same as with key on, engine off.

But with pressure in the 20s, it sounds like a weak pump, unless the FPR is to blame.

GTA88

Thanks for the update. Sounds like not too high of a price for all the work done (and it is a lot, to drop the tank, as we know, plus diagnostic testing).
Good luck with it in the future!

I looked at one spark plug on my car, and it was very clean, and the gap was still perfect ( .045, I think), even though the plugs now have 30,000 miles on them. I tried to pull a plug from the other side (passenger side). Jacked up the car, got at it from underneath, and couldn't get the boots off the plugs!
Even with a good grip and angle on them. I was afraid I'd break something, so I stopped. Well, at least I know the boots are securely on. I'll have to have a mechanic do the plugs, if it comes to that. Had a mechanic do them last time.

I guess it could be the injectors. I thought they were supposed to last forever. Guess not.

My maf throws 33 and 34 codes now and then, it comes and goes. Been doing it for years, with no bucking or hesitation. Right now I just keep the air intake elbow off, and the car idles a lot better, and drives the same (still has the intermittent hesitation though).

Or, of course, could be the weak pump.

Johnstonxj

80's GM. A constant love/hate.

GTA88

Thanks for the reply.

The mechanic who said 10 psi was the lower limit knew I had injectors, since he also said the injectors might be the problem.

I think I have ruled out the fuel pressure regulator, Removed vac line, no change in rpm or pressure, no gas smell, no leak. Clamped off return line, no change in fuel pressure.

Seems like all 26 psi is being used up by the running engine.

I put the trans in gear, foot on the brake and revved the engine a bit. No change in pressure.

Still looking for my vacuum gauge!

At this point I'm 'hoping' it's the weak fuel pump causing the problem, even though it will be expensive to have a mechanic replace it, at least the problem will have been fixed.