Wife's 02 3.4 Monte cranks but won't start. Everything else the BCM controls works fine. I replaced the ignition lock cylinder, passlock sensor, and ignition switch. Ran like new for a few days then problem returned. Took it to a dealer, they replaced fuel pump and filter. Ran for a few days and problem returned. Back to dealer for two weeks. MAF was throwing some wild numbers replaced it free of charge and had someone start the car every time they went outside. Ran great for a week and problem returned. I installed a New Rockies Module and afterwards it wouldn't crank until doing the security relearn, then it cranked but wouldn't start. I checked for spark at all six and it was good. Car runs so good when it starts that I'm certain there are no mechanical issues. Shot some starting fluid into intake and car runs until it burns off. So, we're down to a fuel issue. Replaced fuel pressure regulator with an oem unit and it ran for 8 days then temps hit low 90's and again it cranks but won't start. I cleaned the ground just forward of the intake box and aft and below the battery. No help. What I've read about the passlock system says once the BCM is satisfied it sends a crank and fuel enable signal to the PCM. Does anyone know if that's one signal or a signal for each? What I've read indicates its a single signal but I'm not sure. I replaced the fuel injection relay, all fuses check. If it was a short I would expect to see a blown fuse. I've looked for obvious chaffing on the wires but haven't found any. I tried disconnecting the MAF and it made no difference. I've read every post I can find numerous times. At this point I'm thinking PCM or wire issue and I'm trying to find where I can measure the fuel enable signal. If anyone has an idea or suggestion I'd sure appreciate it. Oh, and lastly, the two code readers I have show no codes.

 

Man you have check and fixed everything I can suggest.
Check Vacuum lines.
At this point I am thinking the Computer is gone south. Sometimes they can be reset by disconnecting all power. Maybe unhook both cables to the battery. If it wasn't cranking I might suggest the starter. Frustrating for sure.

 

Thanks. I'll check the vacuum lines and take another look at the wires. I'm thinking its the PCM.