After market fuel gauge

Finished my fuel tank on my 65 and Can't get the old gauge or new after market gauge to work. My old gauge didn't work well anyway so I bought a new bosh fuel gauge and ran a new line. I cant remember where the ground wire goes on the sending unit since there is only one post on the unit. Also the new bosh gauge when hooked up just bounces around the F level while hooked up. I tried grabbing the power from the back of the old gauge (which looks like it has a regulator)? and it bounces and also grabbed another power source to power the gauge and it does the same thing?

Any help
?????

Dave

It sounds like maybe the tank/sender isn't grounded. The sender grounds through the tank chassis, so it has to have good contact to the frame. A lot of ppl weld a stud onto the face of the sending unit and tie that to ground. I drilled through the tanks flange near the edge and tied a ground wire from there to the frame with a wire, terminals and stainless pan head screws with star washers.

the original gauge uses a current limiter to cut the voltage down to 6 volts,,,,,,that aftermarket most likely needs 12 volts to it,,,,the output terminal on that gauge goes to the center terminal on the sending unit,,,,,,which is grounded thru the tank or has a ground wire connected to it,,,,,you need to use a matching sending unit with the aftermarket gauge , not the stock Ford one,,,,,

donivan65 wrote:the original gauge uses a current limiter to cut the voltage down to 6 volts,,,,,,that aftermarket most likely needs 12 volts to it,,,,the output terminal on that gauge goes to the center terminal on the sending unit,,,,,,which is grounded thru the tank or has a ground wire connected to it,,,,,you need to use a matching sending unit with the aftermarket gauge , not the stock Ford one,,,,,

Just wondering if they sell new 6 volt replacement fuel gauges so that you could still use the original Ford sending unit with it...

Ok, thanks for the responses. So, if I drill a screw thru the tank flange and ground it that should work? I don’t need to attach the ground to the face of the sending unit?

Well,,,,,,,you can just clamp a wire to the tube and run the other end to ground to test,,,,,,or fix,,,,,,a ground problem,,,,,

Before you add the wire, take a test lead with alligator clips and clip it to the retaining ring on the sender or the edge of the tank and the other end to a clean/good ground and drive it and see if it works. Then drill it and add the wire or do as Don suggests etc. For the other question the tank is well connected to the sender via the retaining ring. In the oem system the tank is grounded via the straps and contact to the weight above it. When I reinstalled my tank I ran into this same problem b/c I put some neoprene foam tape on the straps and where the tanks touches on the weight.