96 Yukon 5.7l cuts out and back in on acceleration

[YukonEddie1959]

1996 GMC Yukon with GM Crate 5.7L engine installed i 2021. Had to have the ECM flashed by FlagShip ONE to get it to run correctly. After that it has run perfectly until two days ago. I went out started it and took off. About the time the engine reached normal running temp it cut out when I accelerated. As soon as I let off the execrator it came back. Tried to accelerate again, and it cut out again. Had to limp it home. Ram a diagnostic with the OBDII tester no codes. Figured it was the fuel pump. Bought a new one and installed it. Seemed OK, until it got about two blocks from home and ag ain it cut out, but came back when I let off the gas pedal.

I have to say I hate "Shot gunning with new parts" but I was lost. I have installed a new Cap Rotor, Cam positioning sensor, fuel filter, and it still does it. I have a new fuel pressure regulator I' installing tomorrow.

I called Flagship One and got an RMA but they have not replied yet. The ECM's they flash to match your VIN Number so everything is as it should be. They have a Life Time warranty. I am hoping that they will flsh a replacement for me, and it solves the problem.

Any ideas and or sugesstions here will be gratfully acepted.

 

[Eman85]

Just a dumb question but why did you have to have the PCM flashed to get it to run correctly when you installed a factory replacement crate engine?

 

[exp500]

Try a live data scan first while at idle, then driving. See what items are out of bounds.
A fuel pressure check with a 6 foot hose up under wiper helps while driving too.

 

[YukonGTmaster]

Check that the negative and positive terminals on your battery are clean and tight. I had your same issue, when I would accelerate the battery would lose connection momentarily, and the engine would cut out.