04 Pontiac Grand Prix GT2 stalls on first start up

[jwbouch]

My Pontiac Grand Prix, irregularly, will stall out when I first start it. If it stalls, it will continue to stall unless I tickle the throttle after starting it. Once it is started I don't have any issues with it. It doesn't happen very often, but often enough to annoy me, and I have no idea where to start. Thanks!

[Drew Dowdell]

I'm guessing you have a 3800?

[jwbouch]

I'm guessing you have a 3800?

I do. I have the non-supercharged 3800. Being new to this whole thing, I don't know what all information I need to post. Let me know if you have other questions.

[Drew Dowdell]

Cold weather? Does temperature matter?

[SAmadei]

Does it happen mostly when its cold?

Last year, I had this problem after I redid my plastic upper intake manifold during the cold months. Mine would start, stall and wouldn't idle unless I gave it a bit of gas... Some days, it would throw a code, lean condition. Apparently something didn't seal perfectly at first and I have a intake leak... causing a slight lean condition. I checked all over and couldn't find it.

After a few months, the summer heat and some gumming up seems to have helped seal everything and the problem went away.

I assume you have the Series III 3800, so you don't have the plastic intake upper manifold, but if you developed a leak, I think you would see the same thing.

The '04 GP in my household is a supercharged, so I can't really account for all the differences between my '99 series II 3800 and your '04 series III.

[jwbouch]

Cold weather? Does temperature matter?

it seems to be without pattern. Sometimes it's raining, sometimes it isn't. It happens in the summer, it happens in the winter. It sometimes does it on the first start of the day, sometimes it will act up after it's been running all day. I really can't figure a pattern out.

[jwbouch]

Does it happen mostly when its cold?

Last year, I had this problem after I redid my plastic upper intake manifold during the cold months. Mine would start, stall and wouldn't idle unless I gave it a bit of gas... Some days, it would throw a code, lean condition. Apparently something didn't seal perfectly at first and I have a intake leak... causing a slight lean condition. I checked all over and couldn't find it.

After a few months, the summer heat and some gumming up seems to have helped seal everything and the problem went away.

I assume you have the Series III 3800, so you don't have the plastic intake upper manifold, but if you developed a leak, I think you would see the same thing.

The '04 GP in my household is a supercharged, so I can't really account for all the differences between my '99 series II 3800 and your '04 series III.

I have never thrown a code. The check engine light has never been on since I bought the car 2.5 years ago. I can't detect a pattern, which is why I can't figure out what it is. It has been doing this for a year or more.

[Drew Dowdell]

I'm going to diverge from SAmaldei and suggest that you might have a fuel injector issue.... and if not there, fuel pump.

[SAmadei]

I'm going to diverge from SAmaldei and suggest that you might have a fuel injector issue.... and if not there, fuel pump.

That would be my next thought. Borrow a pressure tester and put it on the rails' schrader valve. IIRC, you need over 50 psi.

[Intrepidation]

If it were the fuel pump going I would think the issue would not go away after the car got going, you'd have problems with it during operation as well. It could be dirty injectors or malfunctioning injectors, it could be a dirty throttle body, it could even be sensor, such as the MAP or MAF sensor (I dunno which one GP's used).

[SAmadei]

If it were the fuel pump going I would think the issue would not go away after the car got going, you'd have problems with it during operation as well. It could be dirty injectors or malfunctioning injectors, it could be a dirty throttle body, it could even be sensor, such as the MAP or MAF sensor (I dunno which one GP's used).

The line tends to stay pressurized... if you have a leak down, either the pump or a small line leak, the pump can take a few moments to get the pressure up high enough to keep the car running... but once its on for a bit, it'll keep the pressure at a sufficent rate.

You can test for this by letting the pump run a minute before starting the car... just put the key in run for a minute... you'll hear the pump in the rear... then start the car.

[jwbouch]

I'm going to diverge from SAmaldei and suggest that you might have a fuel injector issue.... and if not there, fuel pump.

I checked the pressure of my fuel system, and it was at 55psi. I believe that is right where it is supposed to be and indicates there are no issues? I have read a lot of other people have had problems with a dirty throttle body and that has caused the stalling issue. I just cleaned the throttle body today and so far, so good. However, this stalling issue is hit or miss, so I'll see how it goes for the next few days. I'll keep you up to date.

[daves87rs]

Hopefully she just needed a good cleaning...

[jwbouch]

Hopefully she just needed a good cleaning...

So far, that seems to have done the trick. It is starting a lot smoother and doesn't stutter at all, or stall out (as of yet). I'm much happier with having to have bought a $7.00 can of throttle body cleaner then a $300+ fuel pump!

[daves87rs]

Nice!