I don't think there is one, its a mechanical fuel pump operated off the
cam shaft, opposite the distributor. Only real electrical part is the
fuel cutoff solenoid which shuts off the gas when you turn off the
I have a 77 with 20R. The factory manual doesn't show the location. It is
definitely an electric fuel pump. I can hear it buzzing away just before I
start the motor. (key in run position)The wiring diagrams don't show the
pump or the relay. Themotor manual does have a diagram of the fuel pump
circuit. I'm not an electrical wizard, so bear with me here.
ignition start has a direct connection to the relay.
ignition run connects to the relay via a fusible resistor
one wire out of relay to fuel pump
oil pressure switch has 1 wire that splits, 1 to oil pressure warning light,
the other to the fuel pump relay, and out to the fuse that controls the oil
pressure warning light.
fuel pump runs while starter is turning, or when oil pressure is present.
(Hmmm- don't know why mine runs with key in run position but motor not
running, but original owner may have changed something)
pic of the relay shows a normal looking relay (just a small box) with all
wires coming out together to a 5 pin connector.
manual also states not to operate the pump without the resistor in place
also mentions checking resistor for continuity- 1.4 ohms for reference only
Not having seen it I can't say for sure, but I would start looking behind
the dashboard in the gauge area.
Hope this helps.
Every day is a good day- it's just that some are better than others.
If it slike the later fuel-injected trucks, then there still is no fuel
pump (only) relay. Its called the "circuit opening relay" and is
located in the passenger side kick panel area:
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