94 GMC Yukon 4wd, with a 350 5.7 litre TBI. won't to start Resolved.
94 GMC Yukon 4wd, with a 350 5.7 litre TBI. won't to start. The fuel pump won't come on,
but it will run with starting fluid or pouring gas in the throttle body. RESOLVED, ANSWERED
After removing the tank, cleaning all connections, replacing the fuel pump, pressure regulator, ECM,
Ignition module, engine temp sensor, throttle position sensor, coil, plugs cap and wires, fuel injectors,
oil pressure sensor and verifying all the wiring and ground from the relay to the pump were functional,
and also replacing the relay itself, the pump still wouldn't work. I checked the impulse voltages to the
relay, and was not getting a good read.
I jumped the fuel pump, and made sure i was getting pressure at the intake (i was, ~55psi). The
engine would run sporadically, but run real rough but then quit running all together.
I've checked all the obvious fusses and wires.
RESOLVED: The problem was a the orange fusible link wire that supplies voltage to the
fuel pump relay on the fire wall, under the cover on the passagers side. The wire was corroded
internally, so power was not getting to the relay or the PCM/ECM. It was a $5 fix and was not visible to the
eye. The inner wire was corroded and was only detected by probing with an volt meter.
Check here for 12 volts
Check here for 12volts (below). wire was corroded internally and undetectable without testing at both ends. thus
no power was getting to the relay