ICUALL

Okay a quick history 2000 Vette Coupe : Just changed the Engine wiring harness and put in a 427 Short block. When the key is turned no fuel pressure. If I crank the Engine I have pressure as long as engine is cranking, when it fires up and key is released, the fuel pressure drops to 0. If you manually trigger the relay in the underhood fuse center the pump runs fine. remove the ground signal and pump turns off. You can start and run the car as long as you trigger the fuel pump relay manually. HOWEVER it stops running after a couple minutes. (Could be injector signal shutoff y PCM ?)

Any ideas where to start looking? I have traced and confirmed a good connection between the fuel pump relay and PCM. Relay Ground connection is fine. VATS system has been bypassed. No DTC are set when this happens.

Can anyone explain what the computer looks for or requires to maintain fuel pressure and injector pulses?

lucky131969

What do you mean "trigger"....and what "ground signal" are you speaking of? The fuel pump relay receives 12 volts from the PCM under two conditions:

1) For two seconds when the pump is primed(key to "on")
2) When rotation is sensed by the PCM via the crank sensor output.

The ground at the fuel pump relay is constant(not triggered on or off), and is provided from SP122(under the battery tray), which in turn gets it's ground from G105(lower left side of block).


http://forums.corvetteforum.com/c5-t...e-grounds.html


Diagram and relay check .......start with post #4:

http://forums.corvetteforum.com/c5-t...-the-road.html

ICUALL

http://forums.corvetteforum.com/c5-t...e-grounds.html provided the answer ! G107 was missed during the install, grounded it and engine fired right up. Now for the new tune and dyno !

lucky131969

Hmmm....that does not make any sense. G107 provides a ground for the coil packs(both banks).....not the fuel pump. If G107 was off, you should have had a boat load of misfire/ignition codes.

ICUALL

[Forgot to mention that we also redid the grounds at SP122 and G105 !
We were actually have a problem with the fuel pump relay and then found intermittent no spark which was traced to G107.

Bottom line check and recheck the engine harness ground points if you encounter a no start after changing the engine harness...


quote=lucky131969;1576144613]Hmmm....that does not make any sense. G107 provides a ground for the coil packs(both banks).....not the fuel pump. If G107 was off, you should have had a boat load of misfire/ignition codes.[/quote]

lucky131969

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