The cars a 2000 camaro z28 ls1 auto 82k miles
Mods: ls6 intake, lt headers, exhaust and a tune. Egr and AIR deleted


For the past couple months I have had a very rare occurrence where my car doesn't run well the first time I turn it over. Il turn it, it will start, idle rough around 300 rpms. Then it either bogs out or I shut it off. Most of the time I can start it fine the second turn. This happens very rarely and starts the first turn 99% of the time. Today was different though, every time I turned the car off and let it sit , I'd have the same symptoms : bogging and hard start. I checked fuel pressure, it's 60 while running and 50 when I turn the key to the on position. It would slowly go down over time. I sprayed maf cleaner around the engine to see if there's a vacuum leak. I couldn't detect a leak. Any ideas guys?

 

Does the fuel pressure continue to drop with the key off or is it holding pressure? I had a similar problem from leaky injectors would make my truck hard to start if it sat for a few hours or overnight, 3 of 8 were leaking. It would run ruff and bog when first trying to drive away but then clear up and run fine.

 

Same on mine(early 5.3 truck motor) but fuel pump mostly. I first suspected injectors. It showed pressure but wouldn't keep it there all the time apparently... only when I wasn't looking. Would run FINE for hour or more and get iffy when it felt like it. Got almost totally better and then I changed the fuel pressure regulator... which older models have. Does yours have the vacuum-referenced regulator?

 

Just to add a conclusion to my problem. The PO replaced the alternator. When I started looking into the problem I found a loose bolt on the alternator. I tightened that up and made sure the battery was hooked up good. After that , the problem has disappeared. I'm guessing the fuel pump was getting enough power or something wasn't grounded maybe.... Idk but I'm glad it starts right up!