Pontiac: Follow Up, warm sunny days, grand prix gt

Question
ORIGINAL QUESTION IS BELOW

I have checked the fuel pump and it is ok.  There is no problem starting in the driveway or anything, just on the highway 5 min after leaving work, normally on warm sunny days.  No mechanics around here have heard of it.  If you know anyone else that might help please let me know.
Thanks!



Subject   Pontiac Shut Off
Question   I have a 1999 Grand Prix GT, 6cyl, 3.8 eng, auto trans; My problem is: After leaving work only, (never in the morning on the way to work) on warm days as well, and driving down the highway at approx. 120 km/h (75 mi/h) for 5 minutes, my vehicle will shut off, but if I continue to roll I can restart after 7-10 tries.(Sometimes it will start after 2 or 3 tries) Or if I have to pull it over for a minute or so it will start right back up. The "service engine soon" light does not show any computer problem. Can you help me? Thanks!

Answer   There are alot of problems with the ignition switches on your car. That is probably the first thing that I would look at. Its hard for me to say what else it could be without knowing if it stalls due to a fuel problem or an ignition problem.  

Answer
I have seen a plugged fuel tank vent cause this problem. It only happens when it is hot and driving down the highway. The suction from the fuel pump will actually cause the plastic tank to colapse. When it does this the bottom of the tank will "suck" up against the bottom of the pump and stop it from getting any gas. After it stalls the suction is released and it will be ok. Also a broken baffle in the tank can cause the same thing.