Fuel pump question ['83 245]

Still chasing my starting troubles. (I can't get a harness from Dave
until next week...)

If I disconnect the yellow wire connector under the rear seat (main fuel
pump wires) and put a meter on the ground and yellow wire the meter
shows zero.
When I spin the motor, the meter shows 12V.
Seems like this would indicate the wiring, relays, etc. to the main pump
are good.
If I jumper 12V to the yellow wire going to the pump, the pump does not run.
Do I have a bad pump?

 

That's what you want; the circuit isn't energized.

Again, what you want: circiit is energized from fuel pump relay.

Almost certainly.

Either a shot pump, a bad ground wire/connection from the fuel pump to
the car, or a bad connection at the pump itself.

 

I pulled the pump and put 12V right to the lugs. It twitched like it
wants to run but nothing. Beat it on a rock but it still doesn't run.
Time for a new one.

 

New pump and it runs...
I put an aftermarket one on it until I can order a Bosch unit.

 

One word of caution, I read the fuel pumps were only meant to run
submerged in fuel and one should not try and put power or "spin" one
with it out of the tank and fuel. Also, you don't want to spin it in
the tank by applying a meter that could spark.

 

I test pre-pumps in a tub of water, yes it sounds like a bad idea to put
something electrical in water but it beats it catching fire from fuel
vapor and it's easy enough to spray some WD-40 in it to displace the
water if the pump does in fact still work.