"Past full and stays there" is a sign of no continuity through the sender circuit. Disconnect and ground the purple wire on the connecto on the car harness. Guage should go to empty. Then check the purple wire to ground with an ohmmeter on the sender unit side harness. Should be 0-90 ohms depending on how much fuel is in the tank.
Or, take it to a competent licenced mechanic.
-- Edited by DaveM on Tuesday 14th of May 2013 09:04:25 AM
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I'm trying to determine if my sending unit is pooched or if its wiring. I've got an autometer fuel gauge that goes past full and stayes there. I'm trying to determine if its the wiring or not but I'm into sure how the wiring goes on this sending unit. The tank and unit is out of a mid-80's full size blazer. I've got 3 wires coming off the unit with 2 of them giving me 12 volts. Anyone have any ideas or know how the wiring is supposed to be on this particular unit?
I do know on Chevys that the body of the sending unit has to be grounded to the frame or the gauge will go way over full and stay there. Is yours grounded?
Hmmm!! You're saying that you have 12v at the sender? I have Autometer gauges in my car also, and if I recall the sender in the tank is just a variable resistor that is grounded. Not sure why you have 3 wires.
I've got purple, green and black going into the sending unit. I unplugged the sending unit from the gauge and now only have 12v on the green wire. So you guys were right 1 ground, 1 12v and 1 sending unit. I grounded the purple wire and the gauge stayed full, I made a jumper wire and went from the purple straight to the gauge and it still stayed full.
I'm off the next few days so tomorrow I'll maybe pull the unit out and bench test it.
-- Edited by Grumper on Tuesday 14th of May 2013 08:43:58 PM
