I am trying to narrow down a problem.....fuel gauge stopped working or works intermittently. Is it sending unit or bad gauge?
Fuel gauge or sending unit (1 Viewer)
- Thread starter benhoffa
- Start date
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AlaskanWheeler
SILVER Star
It appears to me the fuel gauage is basically a voltage meter. So, if you had a variable resistor hooked from the lead of the fuel gauge to a ground, you would be simulating a working sending unit. You would have to know what the specs on the sending unit , not knowing could cause you to direct short to ground and possibly destroy a working gauge. This method would eliminate the need to pull the sending unit out, or you could just pull the sending unit, and manipulate the swing arm to see if the gauge is working.
Also be sure you have a good ground wire, at the sending unit, as that would also render your fuel gauge useless.
Also be sure you have a good ground wire, at the sending unit, as that would also render your fuel gauge useless.
Just ordered a new sending unit for my 78 FJ40 (only $29 from CCT). My gauge drops off when it goes under half tank and then intermittently comes back while driving.
How difficult is it to replace the sending unit? It looks like the tank is just sitting under the passenger seat and the sending unit is in the top.
How difficult is it to replace the sending unit? It looks like the tank is just sitting under the passenger seat and the sending unit is in the top.
I was able to fix the sending unit. If the lug where the wire attaches in the center twists, it can pull the internal wire off the coil. I soldered it back together and epoxied the lug so it would not continue to twist.
The gauge is a voltmeter and the sender is a variable resistor. In a '78, at least, there are two wires going to the sending unit. It does not depend on chassis ground. One wire goes to the insulated center lug and one wire attaches to one of the mounting screws. I don't recall what the resistance range is, but I do recall that the voltage is limited to something less than 12v.
The gauge is a voltmeter and the sender is a variable resistor. In a '78, at least, there are two wires going to the sending unit. It does not depend on chassis ground. One wire goes to the insulated center lug and one wire attaches to one of the mounting screws. I don't recall what the resistance range is, but I do recall that the voltage is limited to something less than 12v.
Replaced sending unit and I am back up and running with a gas gauge again! Super easy fix for those of you with limited experience. Probably took 20 mins (because you have to remote passenger seat).
