Hello all! New vette owner here chasing a random no start and run like doo doo issue. I have poked around a bit but have been getting an extremely wide variety of symptoms so I'll rattle mine off here and hope someone has had something similar.

The car is a 2007 with the LS2. When I got it, it ran fine. Drove it home 10 hours from Maryland without a hitch. Few days later, I went to start it, and it would crank and crank and crank, but not fire. Few mins later, boom, fired up and ran without a hitch. Some days it would start fine again all day. Next day it was random whether it would start on the first try or not.

Fast forward a few more days of poking around for answers on why it doesnt start, I purchased a fuel pump relay from NAPA and replaced it. Car started fine for 2 days. After a hard rain storm (Which I think was personally coincidental) the car started but ran very rough. It was noticeably bad. I took it down the road and it was hitching slightly around 2000 rpm. If you were to stab the gas, the car would fall flat on its face like it didnt have fuel, then take off abruptly and stumble again randomly.

The car has the Racetronix fuel pump rewire kit. I checked the 20 amp fuse in the engine bay. Looked fine but i put some dielectric grease on it anyways. I cleaned the battery terminals and greased them as well as the ground near the front of the engine bay by the fuse box. I havnt done the driver side one yet but its on the list.

I purchased a fuel pressure tester and put it on the schrader valve on the rail. Pushing the ignition button but not starting the car yields no fuel pressure sometimes, but it builds pressure at other times. When attempting to start, it often has no pressure, but builds some after a few attempts. Then it will start and run and it runs at a full 60 psi, even when revving. I was certain it was the fuel pump but I feel as though the pump should run weak if it was that bad. I could be wrong of course. Anyone have any ideas or can relate?

Thanks for looking.

 

Are there any codes, a lot of parts stores check them for free. OBD2 basic scanners are inexpensive and will do more than just read codes.

 

Another is to remove the Racetronix plug and play harness and try on just factory harness or just add dielectric grease.

You can have a Walbro 450 lph. pump on factory harness no issues.

 

I dont have any CEL's or anything, but I am willing to limp it down the street to VatoZone and see if there are any codes, new or stored.

I will try that as well Boost. I want to examine the harness in the bay and at the end near the tank anyways for any burnt or faulty wiring.

 

check your ect sensor. it may be bad. using a scanner check the reading. say its cold and doesn't match the ambient temp. For example (excuse me I'm Metric lmao)
its a 25c day and car hasn't ran at all but ECT reads -40c there is your problem. Located on the head behind the ALT it's an easy swap if so.

 

Check the starter solenoid where the + battery cable attaches. They are prone to break causing weird electrical issues

DJ

 

The fuel pump wire terminal where it terminates for the fp relay inside the fuse block is most likely not making a good connection. Often when you disconnect and reconnect the fp relay it jars the clip enough to make contact for a short time. Hence why the issue is intermittent.

Trace the wire, pull apart the fuse block, pinch the connector slightly and add dielectric grease.

Sometimes even just jiggling the wiring harness at the fuse block will get it started.

Also, you should have constant fp even after shut down...there is a check valve to keep fp constant in the line and fuel rails. Although I've seen them bleed down over time which is not a huge deal. If you have power to the pump at start up the line will pressurize instantly.