RS246.com Forum :: The World's #1 Audi R, S and RS Enthusiast Community

First I'd like to say 'Hi' to everyone on the forum. I've been lurking for a while, and finally have a problem that couldn't be answered by using the Search function.

To be brief, there is no trigger signal from the ECU to the fuel pump relay so car will not start.

I am in the very final stages of Stage 3 upgrade...car started and ran once everything was put back together...then rear main seal leaked (it had been replaced). So out comes the gearbox, replaced seal, back together, and car will not start. Odd as nothing relevant to the fuel system was touched. Finally trace fault to (apparently) the ECU. It seems it is not sending trigger signal to the fuel pump. There are no fault codes either...

So I have two questions. Does anyone have any idea what could cause the ECU to fail to send the signal to the relay?

And does anyone know what voltage that trigger signal should be? I would assume 12V, but I am not certain. I was hoping to grab a feed from somewhere else to trigger the relay so we can at least get the car running and check for any other problems.

Any help is very much appreciated.

Regards,

Jeff

maybe the fuel pump has shat itself jeff, it will need a 12v feed , is there power to it =no. take a live from the battery to the pump,change the relay. failing that - grab a tinny mate

When I first went stage 3 my fuel pump fuse blew (on the main fuse panel in the side of the dash). For some unknown reason, a previous owner had replaced it with a 5amp fuse (should be 10 I believe)!

Check the simple things first!

Thanks for the replies...

I should have detailed a few more things. Fuel pump has been replaced--as the original did give up. All fuses have been checked and everything seems fine. It really does look like ECU is not sending trigger signal to the relay when ignition is on...?

Most modern management systems wont turn on the fuel pump until it knows the engine is spinning for safety reasons. Ensures the pump gets shut off in a collision.

As such i suggest you take a look at the crank sensor, as thats bolted to the gearbox bellhousing which you have removed

If the crank sensor is unplugged or damaged, the ecu wont know the engine is spinning and the motor wont start

The pump should run for a while when you switch on the ignition. If it doesn't, there is fuse blown somewhere or fault in ECU.

check crank sensor