I have an 89 civc dx hatchback with d16a6. The fuel guage has worked properly and read acurately since i bought the car, until i was having fuel issues and thought my return line may have been clogged and blew some compressed air through the return line (ended up being a stuck fuel pressure regulator and has been replaced). But now the fuel gauge on the cluster will only go up to about 3/4 full even when im at the gas pump and fill it until it overflows and it acts like that is the full line because it starts going down from there like it would normally if it was at the full line so by the time its on empty i probably still actually have 1/4 of a tank left. just curios if anyone had any suggestions or things i could try. i was really trying to avoid dropping the tank but i feel like it must have something to do with me blowing out the return line since it happened right after i did that. Thanks for taking the time to read!

 

Ground the fuel gauge wire at the sending unit in the rear.

Turn key to ON(II)

Does the fuel gauge needle rise to the full mark?

 

this would be one of the wires under the back seat correct. I think there are 3 wires. Do you know which color that would be?

 

Yel/Wht wire