On my 2000 RS, the fuel pump relay isn't turning on. It has power in, power out (to the pump), ground for the coil and a power for the coil.

The pump is functional, because if I go to the fuel pump directly and give it 12V, it turns on. So its not that.

I've tried 4 relays and I doubt they're ALL blown, but taking the fuel pump turn on signal wire (LtGreen/Black) and giving it power, nothing happens.

Anyone have any idea?

Start from the outside and work your way in.
Do you have power AT the pump? Where are you probing for power?
If you had power to the pump and the pump works when you put voltage directly to it, it should be working.

Take your meter, and probe the power wire at the connector that plugs into the pump module, then have someone turn the key to "ON" and see if you've got voltage.

The "turn on signal wire" is simply closing the high power circuit inside the relay, which should provide battery voltage to the fuel pump if the circuit is complete. Applying voltage to the low side won't make the pump run if the high voltage circuit isn't closing.

Okay, when probing for power:

I have no power after the relay.

When using a test light to provide power (direct from the battery) from the pump back:

- Power to the pump, turns on
- Power from the passenger's side kick panel (which goes to a couple other connectors, then to the pump), turns on
- At the relay, "output" side of the relay, gave power and turned on

So the problem is at the relay, but my relays worked fine before, and I have four of the same kind, at least one should work, right?

The way the pump power system works in the RS: Relay has power 'in' from Main Relay, Wire 'out' to fuel pump. Has coil ground wire, and coil 'control' power wire. ECU powers the coil control wire, which turns on the relay, completing the circuit between the Main 'in' and the pump 'out', which would turn on the pump.

I guess its basically boiling down to something at the relay is ****ed, but I don't know why. Is there any way to test the relay?

Well the simplest way would be to swap it with a known good one and see if it works. Just switch it with, say, the A/C comp relay and see what it does.

You probably already know this, but you're only gonna have power out of the relay when the key is first switched to on, or when the car is running. So hopefully you're not looking for power out of the relay all the time, right?

No no, I'm definitely not dumb. :) I'm completing the last peice of the puzzle to my V3 swap...it runs otherwise.

You're right, I'll start there.

If you've got signal to the relay, and you swap in a known 100% good relay and it doesn't work, take a look inside the power block and make sure everything's solid in there. You might just have a loose pin or some corrosion in there.

In addition to the relay, there is also a VFD controller in there to modulate pump duty cycle.

edit - actually that only comes on the factory turbo. your setup might not have the VFD.

Yeah it doesn't have a VFD (FPC?) , confirmed it with ECS.

Its just 12V all the time, controlled by a relay.