1975 280Z fuel pump issues (long)

[mtcookson]

For those who don't like to read, cliff notes are on bottom right above my questions.

I just recently bought a 75 280z and have been getting it to where it can run again (been sitting for 2 years). So far, I've fixed some wires that a damn pack rat ate through, cleaned up the thing's mess, put in new spark plugs and wires, new air filter (pack rat ate through that and made a nest in the air box which i cleaned up), i drained the fuel tank, put on a new fuel filter, and am getting ready to change the oil and oil filter.

I cranked it over early on to make sure it wasn't locked up or anything and it cranked over beautifully. One thing I noticed though was that I never heard the priming charge from the fuel pump. I checked for more wires and looked around for a possible cutoff switch but didn't see any so I went on the tedious task of taking the fuel pump out. Got it out and touched the terminals to a battery... nothing. I was about to give up when all of the sudden I got the bright idea to take it apart.

I took it apart and found the part that spins so I tried spinning it with my hand but it wouldn't spin. I put a rag over it and put some channel locks on it to break it free and it did so instantly. I could then spin it with my hands. I hooked it back up to the battery and it spun fine so I put it all back together and checked it again on the battery, still worked.

I toss it in the car and turn the key to the on position to listen for the priming charge... still nothing. I got a multimeter out and hooked it up to the pump to see if I was getting any voltage. Turn to the on position and nothing however... when I try cranking the engine the voltage goes up to 7 or so volts, which doesn't seem correct to me at all.

Cliff notes:

Fixing up car, fuel pump doesn't work, take out fuel pump, its locked up, i free it, test it multiple times to make sure it works, put pump back in, turn key to on position for priming charge and hear nothing, hook up mulimeter and there is no voltage to do a priming charge, when i try starting the car the multimeter says there is only 7 volts being supplied to the pump.

I guess my questions are, is there supposed to be an initial voltage for the fuel pump to prime the fuel system, is the voltage supposed to be lower like the 7 I had read or is it supposed to be 12, and I guess lastly could any of you point me to the location of the wires that go to the fuel pump and also the "electron fuel injection relay"?

Many thanks in advance if you guys can help me out on this!

[Zedrally]

You still should measure 12 volts or better. I do in the 260.

7v indicates all is not well in the system.

Not being familiar with 280's this may be incorrect advice.

[mtcookson]

I personally have to agree with you. It just doesn't make any sense to me for them to run 7 volts. I think it should be 12 so I'll peak around and see what I can find. I now know where the relays are and such so I'll test those and the wires.