well i was testing my fuel pump cause i was not getting any fuel and there is 12v to the pump but it still wasnt working. i tested the pump and its good. i jumpered a ground to the pump and it starts. so where would my ground for the fuel pump be? also my fuel level gauge doesnt work. any and all help will be appreciated.

 

The manual shows it back near the right rear tail light. I mean you've got to drop that curtain that covers that area, then take a look. Can't miss it. See free online FSM wiring diagrams. Ground number 25 page 50-37 of the series four wiring diagrams.

 

well i checked that ground and its on there. could i have a chasis grounding prob? my fuel level gauge is also not working btw its a s5 na

 

Yeah. The fuel level gauge/sender also use that same ground.

The fuel pumps elect connector has four wires. The BLUE is the power from the circuit opening relay to feed the fuel pump and only the fuel pump. The BLACK is the ground for the pump and level sensor.

You could take a long piece of wire. Somehow put one end to a KNOWN ground. Maybe put a ring terminal on that end and bolt it down. Then, take the other end of the new wire and shove it up the back of the BLACK wire on that fuel pump plug. Now you should have a good enough ground for the pump to work and the level sensor to output. It's temporary of course, but it should work.

When I say fuel pump plug, I mean the half that is a part of the chassis (rear) harness. NOt the colors on the half of the plug that belongs to the pigtail harness on the pump itself.

I might go look at my car for that ground. I'm sure it's where I said. The wiring manual shows it there. The page with the fuel pump wiring.

 

Sorry about the first two jpg blurred. Camera was set wrong for the first two and I'm not going to take more pictures. Third is clear.

Ground point 25 is the ground for the fuel pump according to the first two jpg.

So I unscrewed that gnd and the car still ran. Huh? Book must be screwed up. No it isn't. The third jpg explains why the pump didn't die. The 25 gnd is also tied into the JC-02 ground in the front harness as shown with my red lines on the dwg. So you can lose gnd 25 and the pump will still run.

I don't know what to tell you other than that. Getting a meter out and ohming the black wire in the fuel pump connector could prove if that ground wire is grounded or not.

About the fuel level light. Put one end of a wire to ground. Then the other end of the same wire into the fuel pump plug where the WG or white green wire is. I'd have the key to ON prior to doing this and be STARING at the fuel level gauge at the very same time you touch the gnd to the WG wire in the fuel pump plug. If you see the level gauge start to rise, stop right there and pull your gnd wire off so you don't screw the gauge up. IF you peg the gauge.......ain't good. Just let it move upward to prove your missing the gnd on the plug, or?????????

OR heck, jumper a wire b/t the WG wire and the BLACK wire. Level gauge should rise proving the black wire is indeed grounded.

 

You checked for power at the pump. The BLUE wire. Should only have power there if the yellow, two socket fuel pump check connector is jumpered or if the engine is actually running, or if the afm vane on a series four is pushed aft at least a quarter inch minimum.

IF you saw power on one of the other wires in the plug........that ain't the fuel pump power wire. Only the BLUE. Gnd is the Black. A meter should tell if that gnd is good or not. OR run a new wire to gnd and to the BLACK wire in the plug. Got me.

Anyway, I found out why the car didn't die when the gnd 25 was disconnected from the chassis. And I got to change out my cameras batterys.