255 fuel pump install

[e-dirtym52]

Put in a 255 fuel pump and it won't turn when I turn the key. It has power and I tested the fuel pump before I put it in. Checked voltage and it's only getting 7 volts. I then checked voltage at the relay and it had normal power going in but only 7 volts going out. So question is, is it a bad relay like I'm thinking? Or is there more of an underlying problem happening? Checked ground too and that's good. Thanks fellas.

[e-dirtym52]

Went and bought a new relay from advance and now it doesn't get get any voltage at all. Bmw parts was closed so I tried theirs but obviously didn't work.

[dewme5]

Sounds like you may have a loose wire.

Step through it 1.2.3.

Fuse?
Relay, Power in measures 12v? Power out measures 12v? (I know you said 7 before, and now nothing.)
Good battery connection?
Good ground?
What is the resistance between 12v out of relay, and 12v into fuel pump?
Is the fuel pump running in the wrong direction/wired backwards?

[e-dirtym52]

So this is what I got.

Relay in is 12v. Relay out is 7.5. With advance relay the out was 0.
Battery connection and ground are both good.
Haven't tested resistsance but I can test voltage all the way down to the power wire for the pump. So I was kind of thinking that 7.5v just isn't enough to turn it on. And I know that the pump works.
Pump is not hooked up backwards. Red wire to green/violet. Black wire to the other.

[e-dirtym52]

I got the car to run but the pump won't kick on when I turn the ignition on. But works when I turn the engine over. Why is that,? I'm about to just say screw it and hardwire it with a switch

[mpowerful]

Look into the unloader relay system. I know in m20 the pump doesnt start until you crank. When i wired in my m52 it primes with key on.

[e-dirtym52]

That's what it used to do until I just put this guy in. I can jump it from the relay so I know I have good connections. But I don't know why all of the sudden it's having issues. No loose wires and no popped fuses. Ended up finding spare relays in my tool box but that didn't make much of a difference. It's a late model if that makes any differences. 91 325i