91 C1500 5.0 manual wouldn't start one day, it will start if I use starting fluid and run for a second or two. replaced all the sensors one at a time still same problem. replaced throttle body with new, same problem. Replaced fuel pump, still same problem. Looked at schematic and see a hot fuel module in the circuit Could it possibly be causing my problem???
Q:
Does the fuel pump run for 2 seconds when you first turn the key from OFF to ON?
(No need to continue to the START position. You can actually better listen for/hear the
fuel pump operation without cranking.)
NOTE:
You should also hear the fuel pump running for 2 additional seconds when you turn
the key from ON back to OFF. (Maybe not TBI systems?)
If this isn't happening, you have
to do whatever it takes to make this behind-the-scenes behavior occur.
As well as following the guidance already shared above. (EDIT: I know that this is correct
for '96+ Vortec vehicles. Is this 2 seconds of fuel pump operation immediately after Key
OFF also the same on TBI engine bays?)
Let us know what you discover.
EDIT: I could only find the '2 seconds on' for the Key ON response in a TBI FSM.
(See attached.) If a TBI owner could chime in on what happens to the fuel pump
when you Key OFF I'd sincerely appreciate it. (Note: Since the TBI setup doesn't
hold onto the fuel pressure after shutdown I'd assume that the pump isn't run
during the shutoff sequence.)