Ok, bought a 03 sierra 2500 6.0 a week ago. Bought it not running, supposedly a fuel issue but they didnt really know. So, I put in a good battery and started messing with it. It turns over great, but just wont start.

Fuel pressure 58psi at key on, changed pump anyway, no change

New fuel filter, same

Changed fuel rails and injectors, same

Changed FPR, same

Checked spark on all cyls good

Checked compression, all good

Checked fuel injectors firing, they all are.

Changed the throttle body, same

Changed cts, same

Changed MAF, same

Checked fuses, good

Did security relearn, same

Luckily I have all these parts on hand so it doesnt cost anything to play process of elimination, but Ive run out of things to try.

Thoroughly frustrated, have spark, fuel, and compression, shouldnt need much else. Im going to try the security relearn again, but Im not optimistic. What am I missing?? I read crank sensor will stop spark, so it cant be that. Cam sensor should start 50% of the time.

 

Nothing huh? Tempted to start parting it out lol.

 

Does it even run for a second, then die??... If not I doubt it's VATS then.. Cant hurt to do it again though I guess.

 

Pull the fuel pump fuse and have someone spray some carb cleaner or starting fluid at the throttle body when you try to start it. If it fires up you know its a fuel issue.

 

You need to scan it and see if it's reading any rpms while you crank. If a crank sensor doesn't send a an rpm signal then it will not open the injectors.

 

Every once in a while it will kick, but only a millisecond.

It will kick slightly better on starting fluid, but not enough to run even for a few seconds.

Injectors are firing, all of them, checked.

 

Long shot, but is it possible that the cam is not timed correctly? Maybe they tried a cam swap or timing chain replacement and didn't get everything lined up correctly?

 

Change the crank sensor if you have parts to throw at it. Just because it makes a spark doesn't mean it's making it at just the right time. It's also possible that it could be flooding out OR the cats could be thoroughly plugged up.

 

I have seen flooding before on a swap. The plugs were wet and it wouldn't start at all. We swapped the plugs and it fired right up. Have you pulled one to see if there was fuel on it? That would also confirm that you're getting fuel through the injectors.

 

heres a silly one.. if your coolent temp sensor isnt working the engine wont start.. try and replace it or check the wires to it..