How do I test the fuel pump?

[dixieflatline]

My in-progress project S3 is turning over, but not starting. My best guess at this point is that it's related to the fuel pump as I can't hear it priming when I switch the ignition on. I came across this thread which looks really useful: https://www.pistonheads.com/gassing/topic.asp?t=12...

I had a question though... looks like the first thing to do is ' run a supply straight to the pump, with another direct earth.' How do I do that? I have a car battery (obviously), jump leads, a multimeter, and a CTEK battery charger.

[Kitchski]

Two lengths of appropriate-rated wire.

One from positive terminal of battery to positive terminal on pump.

One from nega.....you get the idea

[GreenV8S]

Preferably with a fuse inline with one of them.

The electrical problems I've seen have all been on the positive side, so you probably only need to connect the positive wire (keep the existing earth connected).

[dixieflatline]

Perfect, thanks both!

[Steve_D]

Fuses are used to protect the wiring from burning up and setting fire to the car.
As you will be holding your test wires you will quite quickly disconnect (and swear) if things start to get hot so don't worry about a fuse just for this quick test.

Steve

[dixieflatline]

Turned out to be a much simpler problem - fuel pump relay had gone (gone as it wasn't there, not gone as in blown up). The mechanic who's been helping me with the rebuild had MacGyvered something out of a couple of blade terminals and a piece of wire to get the car started. He'd left it in place but withe one side disconnected. Plugged it in, turned the key and heard the fuel pump prime.

[dixieflatline]

(And then immediately turned it off and disconnected everything again, since while he may have known what he was doing I definitely don't).