Grand Prix Starting Problem

[gtp3.8]

Hi all. I have been wracking my brain over this problem and so far I can't come up with an answer.

I have a 1997 Grand Prix GTP. It has a few mods like a cold air intake, 3.4 sc pulley, 3800 performance pcm and u bend delete. I dont know if any of that would make a difference. I have always been able to just turn the key and instantly the car would start. About 3 days ago I tried to start it and it would turn over for about 5 or 10 seconds before it would start. I bought a new battery and still the same problem. After it starts I can turn it off and back on and its just like new but if I go to the store or let it set for a few min it does it again. I dont have a check engine light. I had it checked out and couldnt find a problem with the alternator. I don't know if its the starter or something worse like timing or a fuel problem. Any advice or ideas?

Thanks

[GTP Dad]

This sounds like an issue with the fuel pressure regulator. It is bleeding down when the car is not running overnight and after a few minutes when you shut it off at a store. Check the fuel pressure at the rail with a fuel pressure guage and see what you have in the morning there should be residual pressure in the line at all times. If there is no pressure then you probably have a regulator problem. Then check it right after you try to start it. If you are getting less than 45 PSI while running the regulator is probably bad and if there is no residual pressure that is a good sign that it is bleeding off. Pull the vacuum hose off the regulator and you may get fuel from it. If you do replace the regulator.

[tblake]

Might be a good time to inspect and clean the IAC motor and throttle plates.

If you put your foot slightly on the gas when you turn the key, will it start easier? Or does that not make a difference?

[richtazz]

I agree with GTP Dad (Lynn) and Tblake (Tim) that your problem isn't with the starter, battery or alternator. The battery stores electrical energy, the starter turns the engine over and the alternator keeps the battery charged. Since the car turns over, they are all doing their respective jobs.

All three suggestions above are solid troubleshooting for your symptoms. Since it's the simplest, pull the vacuum hose off the FPR as Lynn suggested. If there is fuel in the hose, the FPR is bad. If you have access to a fuel pressure guage, check fuel pressure next. If that checks out, do as Tim suggested and remove the IAC valve and check for carbon deposits on it and in the bore it rides in. Last, unplug the MAF sensor and see if it starts easier. Normally a bad MAF will cause a start then hesitate/stall, but I've seen them also cause a hard start, without tripping a CEL.

[gtp3.8]

I checked the pressure today. When I pluged in the gauge it read 0. When I started it it jumped to 55 and then droped to 45 while it was running. When I shut it off it droped back to 0. I think this is the FPR but I wanted to run it by you all just to be sure.

[tblake]

Could either be a bad fpr, or a bad check valve on the pump itself. Did you remove the FPR vacuum line and check for fuel contamination as GTP_Dad suggested?

[rkvons]

Depending on how quickly the pressure drops back to zero, which you didn't mention, you could have leaky injectors that are flooding the engine. I know from experience. Try running the car for a minute, turning it off, then immediately relieve the pressure in the fuel rail, wait an amount of time that would normally make it hard to start and then try starting it. Relieving the pressure in the fuel rail prevents gas from going into the engine.

[gtp3.8]

Sorry it took so long to get back. Yes I checked all of the lines comming from the FPR. I couldn't find any gas in the lines. Does this mean that the problem is else where or could it still be the FPR? Also the pressure would instantly drop back to 0. I did notice that it seemed to start when the pressure reached about 10 or 15 when I was cranking the engine. Is that how much pressure is supposed to be in the line at all times?

[tblake]

the fpr could still be bad, but i'm leaning more towards a bad pump. You could install a new fpr and if that doesn't solve the issue, you know what that means.