What would cause a car to stop starting after being shut off? (Page 1/1) Additivewalnut DEC 15, 09:33 PM I'm fixing my mother in law's 2000 Pontiac Montana with a 3400 in it. For some reason, if you disconnect the battery, wait a few hours, then reconnect it, it runs perfectly. But the moment you shut the car down, it will crank but not start unless you disconnect, wait, reconnect. I have no idea what would cause that at all. Fuel pump is priming, I'm gonna see what the pressure is tomorrow morning, along with checking to see if spark is present. Figured I'd ask if anyone has ever experienced that before or has any ideas on what could cause it. Additivewalnut DEC 15, 10:28 PM Checked, spark is present, fuel pressure good, injectors are not firing Additivewalnut DEC 17, 06:46 PM Bad PCM was the answer! For some reason GM thought it would be cool to put the PCM inside the airbox and let it get covered in water. davylong86 DEC 27, 10:24 PM Wow that's a insane place to locate that. Glad you got it figured out.