Jim's Audi Ur quattro page

Fuel Pump Relay Mod.

Ur's - especially of the WR variety, have a tendency to burn the fuel pump supply wire.
The fuel pump relay is in the fuse / relay panel at the front of the car and there is a long wire to the fuel pump underneath the car below the rear seat.
Just next to the car battery, there is an inline connector in the fuel pump supply wire which tends to melt / burn.
The length of the wire combined with the degradation of the connector add up to a series resistance in the fuel pump supply circuit.
This causes a Volt drop and a slower running pump which can cause fuel starvation under hard acceleration and eventually a fire if the wire is left to burn.

The circuit can be improved by fitting an auxiliary relay close to the battery.
Here is a circuit diagram of the extra fuel pump relay I fitted.

The green wire is the original supply to the fuel pump.
I split the supply wire at the inline connector next to the car battery.
If you get hold of the right size spade crimp terminals you can keep the original inline connector
intact and make some leads to go from each side of it to the relay at the points shown.
I used short wires throughout, at least as thick as the original green/yellow supply wire,
and the relay sits next to the battery - the short wires keep the Volt drop to a minimum.
The Red wire from the battery + terminal should have a fuse in it - a 20Amp should do it.
Because I kept the original inline connector intact, I can always plug it back as original
if the relay fails etc.

Home Links My Car