K100 fuel pump stopped working

My neighbour's k100 has suddenly developed a fault whereby the fuel pump doesn't seem to work - weve tried a new relay and still no joy - the four connecting wires (white, brown, green, yellow) only the brown reads +12v I suspect two wires are for fuel gauge and two for the pump.

Does anyone know which wires are for the pump itself? I'm trying to rule out everything before stripping the tank to get the pump out.

Cheers

It's always difficult trying to diagnose electrical faults at a distance.

My wiring diagrams show the colours from the fuel level sensor (on late models) match those you relate so this is based upon the bike being a 'late' model.

The fuel injection relay has a different combination altogether.

The wires from the pump are black and yellow (late models). These go into the fuel level sensor.

Of the wires that exit the fuel level sensor:

White goes to the low fuel warning in the instruments.

Yellow goes to the optional fuel gauge.

Green/Yellow goes to fuse number 6, then via Green/Red to the fuel injection relay.

Brown is earth.

The FI relay has the above mentioned Green/Red in on terminal 87b, Green/Red out on terminal 87 (to the injectors and throttle butterfly sensors).

Terminal 85 - Yellow/Brown to connector #7 on the ICU.

Terminal 86 - Green/Yellow to fuse #1.

Terminal 30 - Red to battery.

Thanks it's a 1991 J plate - I will have a butchers at the wiring diagram you've detailed and have another look in the morning thanks very much

make sure the rubber pump holder hasent perished and blocked the pump

Thanks I 'bench' tested the pump using the brown n green wires ( granted it was the wrong way round!!) and the pump clicked - should it whirr or whizz ( or generally sound like its spinning ) or does the pump only work one way dc wise?

I hasten to add that I tested it yesterday before I had the helpful wiring instructions!!

Pump's goosed - it should whirr coz its a roller cell type