So i've got a fuel gauge problem that is driving me slightly insane. I have a 1984 Grand Wagoneer limited where the fuel gauge is always showing empty. I replaced the sending unit but still the guage shows empty. The sending has two attachments, one for a red wire, the other a black wire. When I added a second ground wire from the black connector to the frame nothing changes. When I place that second ground wire from the red-wire connection point to the frame the gauge spikes to full and stays there. Thus it seems the gauge is functional.
test the continuity from the sending unit to the gauge; this should tell you whether you have a break in the wire. I used some spare wire to extend reach of my multimeter and tested the continuity. If a good signal is getting to the gauge, your gauge is likely busted.
Ok..try this and feel free to comment..help appreciated. I restored my 85 J20. Pulled tank and washed it out and cleaned Everything..painted Everything correctly. Ground is good and even added new extra ground to cleaned bare frame location. Wire to gauge is all new, ground wire new.
At half tank gauge reads full PLUS. All other gauges working correctly. Dash cluster grounded well with an additional ground wire added just to be sure. New gauge and sending unit from Team Grand Wagoneer, and all installed correctly, new tank vent and all vent lines and fuel lines new. Everything but tank and skid-plate/straps are new. I even cleaned and inspected the dash backing when it was out/apart and cleaned the 'racetrack' ground and all connections and harness. New fuses, New battery, new alternator, new engine harness..all running fine. When I first fired it up to run the cam break-in on new engine..it read half tank and as I started with a clean empty tank, I knew it was exactly a half tank I put in. Then it went to full+ and stayed there when key is on or truck running. ...Anyone ?