Hello,

Love this car but have had this problem for a while. Car will not start or will run rough on an idle after starting it up after 20-45 minutes of being parked -- this time frame is VERY CONSISTENT. Cold starts are fine and immediate restarts are fine. Car runs like a dream during acceleration. Issue gets worse when ambient temperatures get higher.

Fuel pressure is running about 7 psi lower than recommended, but fuel filter is not clogged. Currently considering replacing the fuel pump to address this symptom, but it may not fix the starting/idling problem, so I wanted to ask for advice before I invest that money and time.

The IAC valve and fuel regulator have recently been replaced. I'm planning to replace the crankshaft position sensor next, which have been known to cause stumbling or stalling at idle, usually after normal operating temps have been reached.

I know other Olds owners have had this problem, but I haven't found threads with solutions that I haven't tried. Any ideas?

Thank you very much!

I'm not familiar with the Old'* platforms, but sometimes they will share the same wiring harness'* across Olds, Buicks and Pontiacs. So if you could, see you have the same type of harness in your car with whats in this thread. Your symptoms seem pretty close to this...

https://www.gmforum.com/electrical-1...1999-a-303224/

you should put the fuel pressure gauge some where you can see it(like zip tied to the windshield wiper, then do what ever it is it takes to make it run bad and see if the pressure goes down worse or its something different. what brand of pump and regulator did you use?

@Mike - I scrubbed off those ground buses yesterday as you suggested. The driver'* side was pretty corroded but the passenger'* side was pretty good looking! Put them back in with dielectric grease, and as far as I can tell, it is functioning as usual -- so unfortunately the starting problem is still there.

This morning I actually could not start the car. It was cranking, but not catching. I called AAA and they towed me home (a jump didn't work). Perhaps the fuel pump finally gave out? Maybe replacing it will solve the starting problem? Perhaps it'* not the fuel pump but the crankshaft position sensor? I'm puzzled but not giving up on this car.

@Justin - I have actually tested the fuel pressure with and without the starting problem conditions. It was approximately the same pressure between the two trials (31-ish psi if I remember correctly, which is 5-10 psi below normal). I don't know what brand of fuel pump the car has because it was last replaced 6 years ago when my older sister bought the car. The fuel regulator I replaced about a month ago, and it was a cheap Airtex.

Spray starter fluid into the intake while trying to start the car. If it starts up and dies, you probably need a fuel pump.

Thank you, Roy! It started up briefly with the starting fluid!

I suspected that it would because sometimes when I am having the starting problem, I use that trick to get the car running until the fuel starts moving through the lines normally.

New Bosch (or Carter?) fuel pump on the way.

delphi is the best to get for the pump and regulator. i got a airtex regulator for my yukon and it caused me all kinds of grief because you think you replaced that already but it was doing the same thing, running about 10 psi low, till i took it back and got a delphi one. you probably need both now

Well, I ended up ordering the Denso for $120 since the Delphi was $70 more and had to be ordered from the factory. And don't worry, I knew to avoid the Airtex! (for the important fuel pump at least)

Thanks for the advice!

Oh, I see, you were having problems with an Airtex regulator, not a pump. I figure I'll replace the fuel pump since it'* definitely shot, then check fuel pressure afterwards. Thank you, I'll keep an eye on it since it is an Airtex.

i wouldnt even think of using one for a pump, they are too hard to get at. you can get delphi stuff cheaper from rock auto or amazon, or parts geek