Extended crank when warm or hot on crate GM L31

[texas tough]

is your fuel tank vent clear, smelling gas around the back of the truck may be a good clue.,

 

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Stop replacing parts. Start TESTING parts.

Connect a scan tool, find out what the computer is receiving for temperature input.

Look man... I've been troubleshooting this problem for years now. I most definitely have combed over every bit of scanner data that I can pull from this thing and it all checks out.

Haven't you ever reached a point of head scratching that you just try some common things?

I have two trucks with 5.7s sitting side by side, so a lot of the time it's really easy for me to swap in a known good part.

 

[Fragment]

Have you swapped the ECM yet? You mention it in your first post, but never confirmed that you had tried replacing the ECM.

I have swapped the ECM with a core ECM I received from Blackbear. It made no change unfortunately.

 

[Fragment]

is your fuel tank vent clear, smelling gas around the back of the truck may be a good clue.,

You may really be on to something here. A lot of the time when I shut the truck off it does smell like raw fuel around the back of the truck. Not from the exhaust pipe, but just in the general area.

I replaced the fuel tank when I did the engine swap because the old one was in bad shape. After smelling the raw gas I suspected problems back there... so I dropped the tank again and replaced the little roll over vent valves that are in the corners of the tank. It didn't seem to make a difference. But now I'm realizing that I didn't check the vent lines that go from those valves to the EVAP up front...

I will give this a try soon and see what I can dig up.

 

[1996bluegreychevy]

I'm having the exact same problem for the extended cranking when the engine is hot with my 1996 5.7 vortec and I can not figure it out and I took it to a guy and he can't either. Did you ever figure out the reason for what causes it? Or any one else? I've changed basically every part with a new or good used one and it never even helped a little.