hi Can anyone help?
I have a 1987 k100. fuel gauge is faulty sticks at 3/4 full . although will go to full when tank is full be will not go down to empty.
Any ideas?

If it don't return to empty when you turn off the ignition...the problem is in the instrument...sealed unit.

If it return to empty...the problem is a shorted coil on the level sensor...or something prevents the float arm to use the full movement.