backdoc

I put in a new fuel pump relay in today, and it still didn't start. I think that Tozo is on to something with the ignition. I just don't know what to test. Would it be wise to try to start the car by manually activating the fuel pump relay just to see if it will start? As of now, I can rule out the fuel pump, fuel pump relay, and the sending unit. I have to find out why the relay is not getting power.

taga8

So you have verified that disconnecting the line and starting the car that you don't have fuel coming out of the line? If that is the case, you can start troubleshooting the ignition switch.

backdoc

Starting the car with the relay in, and the hose disconnected....no fuel. If I manually activate the relay, I get fuel.

PaulW

It appears the fuel pump relay is picked up by power being supplied through the 15 bus which is powered through the ignition switch. Power flows across the fuel pump relay contacts 28/15 and 29/S to A4 on the ECM (0.5 mm brown/green wire) to pick up the relay.

If you don't have power on the 15 bus, then replace the ignition switch or at least troubleshoot it like audipages tells you.

Other loads off the 15 bus:

-instrument cluster combination processor
-servitronic control module

backdoc

Pardon my ignorance, but where is the 15 bus?

PaulW

15 bus = 12 VDC bus powered by the ignition switch