Here's what the dealer is telling me......

[chuck121566]

For several months now, my '88 coupe with 36,000 miles has been suffering from what I had assumed was leaky injectors. I have come to this conclusion due to the fact that when cold, the car starts right up. However, once the car has warmed up, the car acts flooded upon restrart 5-10 minutes after shutdown. In addition to this, I own a technical service manual that, from what I can tell, agrees with this theory. With winter in northern Iowa now upon us, I had decided that I would put this fix off until next spring. I took the car to my local Chevrolet dealer today to have the oil changed prior to winter storage...of course, they too noticed the hard start situation. They are telling me that they found it was the fuel pressure regulator and want just shy of $500 to fix it. First things first, I am not a mechanical person....I do however like to think I'm not an idiot when it comes to diagnosis and research....why else would I be here???? My question for all of you is, shouldn't I have the injectors replaced anyway as long as they have the plenum off? In addition, I know GM labor rates are high, but isn't $500 a little rich for this fix?? Let me know your thoughts....and THANK YOU!!!

 

[Hib Halverson]

First thing I'd do, since you have the FSM, is confirm or refute your educated guess about the injectors by running the fuel pressure tests in the manual.

 

[JAKE]

On the 86 I use to own, I had to pull the plenum, runners and fuel rails with the injectors still afixed to the rails to check if any injector was leaking. With the rails off, I just energized the fuel pump and checked each injector for any sign of leakage.

Fortunately none were but I did find the cause of my raunchy idle. I'd mistakenly left an 'O' ring in the #1 injector port when I changed injectors. So that intake manifold opening had TWO "O" rings; one stuck in the manifold and the second one on the injector. Removing the one in the manifold cured my problem.

Changing the FR regulator isn's a biggie at all. Certainly not $500 worth. You can remove the vacuum hose to the regulator and if fuel runs out, it's bad. It's a simple bolt-on swap.

Jake

 

[chuck121566]

Thanks guys....I got the car back from the dealer (without having taken any action except for an oil change) and do see that there is raw fuel in the vacuum lines which would indicate a bad FPR diaphram. I'll borrow a FP gauge from a buddy and do the injector leak-down tomorrow and let you know the outcome. Thanks again for your help.

 

[chuck121566]

Thanks guys....I got the car back from the dealer (without having taken any action except for an oil change) and do see that there is raw fuel in the vacuum lines which would indicate a bad FPR diaphram. I'll borrow a FP gauge from a buddy and do the injector leak-down tomorrow and let you know the outcome. Thanks again for your help.

Now on second thought, would the bad FPR lead to a positive leak-down reading in spite of the fact there is nothing wrong with my injectors? What are your thoughts Hib???

 

[tdr1919]

First, just do the easiest no brainer, hook up a fuel pressure gauge and see what the fuel pressure is, do it without starting the engine, then start it to see what it drops off to. then shut it down and see how fast it bleeds off. If it doesnt come up to specified pressure or bleeds of too quickly then it may be the FPR.
Tom

 

[TedC]

I agree with tdr1919. The right fuel pressure levels are key for a good running L98. With the proper pressure gauge you can check this out for yourself to see what is happening. My 1988 had a hot soak condition that caused hard starting when restarting hot. The injectors were leaking causing a rich condition. I just pulled a few spark plugs after letting it sit hot for 5 minutes and you could smell the raw gasoline.

 

[chuck121566]

Starting with the regulator.....

OK Guys.....here's where I'm at. I've confirmed the dealer's diagnosis the the FPR is bad. I have decided to start there as I now have the plenum off and the FPR off the car. I know that I don't have a need for an adjustable unit as I am dealing with a bone stock application here and have no desire to change that. I see that I can simply replace the diaphram...have any of you had any experience in doing this? I'm leaning this direction as the replacement diaphrams seem to be widely available.

 

[TedC]

Yes, you can just replace just the diaphram. I agree that you do not need an adjustable FPR for a stock setup. What testing did you run to confirm it was the FPR? Also, on a non-FPR topic, I would check out the EGR while you have the plenum off. This is a good time to check for carbon buildup and that the vacuum leak down is with acceptable limits.