2004 pontiac grand prix GTPMods: Walbro 255, HPtuners tune, cold air intake, straight piped, 3.4in pulleyNow to get into the issue. so Friday the car died ideling in some heavy traffic and wouldn't restart just crank, so I being the young strong boy I am pushed it into a parking lot and let it sit for about 10 min while waiting for a ride, tried to start it before I left and it ran for about 30 seconds then died and just cranked after.. My dad came about 45 min later had it running for 20 minutes in the parking lot, and brought it over to me at work (caddy corner to the parking lot) and I got in it to take him back to his car and it died in my works parking lot and wouldn't start again, again cranking and not starting. Got it running about 20 min later, got it to my bay at work and it died yet again. We swapped out the ICM, still did the same thing. Yesterday we swapped the crank position sensor because I've heard that could've been my issue, still didn't resolve it. Key on engine off I get 50psi to the rail, running it gets 67 up until it shuts off (because it shut off it doesn't go under 67 at all). I even made sure i heard the pump running up until it died, and it does. We also checked spark when it wouldn't run just crank, and it HAS SPARK but won't run. Nothing on scan tool data looks crazy, cam & crank sensors look very close (within 5-15 rpm which I assume is normal), MAF, MAP, etc readings all look exactly the same as any other time, day, etc. Someone please give me a lead!We've also cleaned throttle body if that matters at all.
