Hi all
I'm in a bit of a pickle!
My k75, 1987 was running a bit rough at idle especially when cold the fast idle in position one and two when cold it would hunt up  and down  not an even rpm as in the past. A bit of a miss at lower rpm but ran strong at 90kph and up!

Today would not start. No current to pump, pump bench tested fine. 

What colour wires are for the pump on the 4 wire connecter going to the tank.

Do the relays fail?

Cleaned the plug with detox.

Not sure what to do next, help appreciated.

The 4 pin connector under the right hand side of the tank is a known issue. You can try cleaning it and testing it. However mine continued to have the occasional problem so I ended up replacing it with a Duratec waterproof connector from a electronic outlet. Once replaced the problem was gone.
Regards Martin.

The 4 pin tank connector under the right battery cover can go bad.

GRN/WHT is fuel pump 12V.
BRN is ground.

WHT is low fuel lamp.
YEL is fuel gauge.

Thanks guys.
Which is the fuel relay and how to test?

Your fuel relay might have light green casing.



Ground to 85 and 12V to 86 should make continuity between 30 and the 87 pins.

First thing I would do is see if you're getting voltage at the GRN/WHT wire at the connector. You need to hit the start button because the fuel pump only gets power when the engine is turning (starting or running)

If you have power at the GRN/WHT then the issue is either the gas tank connector or in the fuel level sender.

Just tested the under tank plug, grounded brown wire, 12 volts to green white wire, pump works. No power to grn white wire comming to connecter. With ignition, on starter button pressed engine turning over no power to this wire. Thoughts? Will test relay ,many thanks for the pictures!

Fuel relay tested good. Yikes, don't like the look of this so far.
Upstream we go. Which wire gives power to the relay and where does it come from?

Check fuse 6 too.

I am the duffus of the day!

Went over all the things that I had checked earlier including fuse 6. Fuse was good but fuse box contacts dirty or fuse loose. Cleaned it up bent contacts to hold fuse tight, problem solved. Duck your efforts were not in vain, I learned a great deal. Thanks!