Fuel problems 1999 Grand Prix GTP 3800 Supercharged VIN 1: car starts, but shuts down within 10 seconds. You can see the fuel pressure drop within those 10 seconds. If I flutter the throttle, the fuel pressure will jump back up to 50lbs & back down to 0-10. But, you can keep the car running by doing that. I have replaced the fuel filter & helped a little bit, but still shuts down. Replaced fuel pressure regulator & fuel pump & oil pressure switch & still nothing. HELP....this is getting very expensive!

GTP - Pontiac grand prix ? Anti-theft system light lit on the instrument cluster ? Try spraying carburetor cleaner into the intake to see if tries to start then . Anti-theft on your vehicle disables the fuel injectors .

I would replace the TPS sensor. If you have fuel pressure enough to start the car, then you probably have pressure always. Before turning the key to start, turn to ON. You should hear the fuel pump pressurizing the lines. Turn the car back off. Go under the hood and remove the cap to the Schrader Valve. Use a rag to catch any fuel when you depress the valve stem. If fuel comes out into your rag, you should have pressure. Try this a second time to be sure. I had this issue with my car shutting down. TPS sensor replacement fixed it. BUT...it could be vacuum lines, or another sensor fault. The TPS is a common issue. You may also want to clean your Mass Air Flow sensor with the proper solvent and technique.

did you check the lower intake manifold gaskets? they go bad on the 3800 series 2, since you have the supercharger you won't have an issue with the upper intake because it is not plastic but the gaskets may be bad as well. that engine runs best with irridium plugs.

spray your maps sensor with sensor flued only they sell it at your autoparts store

check your fuel filters, fuel line, and fuel pump

When you say it shuts down do you mean "dies"? If so try checking your fuel pressure regulator.

After it dies is the security light flashing?

i would start with fuel pressure test first to see if pressure is constant or fades,,

Maybe weak fuel pump. It pumps when you turn the key on (fills fuel lines) but it dosn't pump enough to keep the car running. Could also be a partially cloged inline fuel filter.

check fuel pump resister. its conector is by the batt. pump runs through it in run, not for 3 sec. when key is turned on. thats why it will start and then quit this happend to my 99 gtp