75 Ford Fuel Gauge
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Can you get to the sending unit wire where it's connected to the sending unit on the outside of the tank? If so, take the wire off and let it hang in the air. Turn the key to run, and watch the guage. It should swing full scale either full or empty(I believe in your case empty). Then take the sending unit wire and touch it to a good clean metal ground on the frame, and get somebody to watch the guage. It should swing the opposite way full scale. If it does, the guage and related wiring all the way back to the sending unit are good, which pretty much leaves the sending unit as being the culprit.
If you are handy, you may be able to fix the sending unit yourself. Either the float has a hole and is full of gas, which you can drain out and fix with epoxy, or the wiper in the electrical box may be broken, in which case I have fixed by carefully bending the tabs back on the box to open it, and then soldering the wiper back together. I have fixed two like this, and they are still working after many years.
If you are handy, you may be able to fix the sending unit yourself. Either the float has a hole and is full of gas, which you can drain out and fix with epoxy, or the wiper in the electrical box may be broken, in which case I have fixed by carefully bending the tabs back on the box to open it, and then soldering the wiper back together. I have fixed two like this, and they are still working after many years.
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Joined: Jan 2004
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From: Western Arkansas
75 Ford Fuel Gauge
Franklin2 thank you for your reply. I went ahead an dropped the tank and everything was good, the wiper was intact an the float was solid, I think my problem is in the wiring at the fuse box.I am not getting voltage to either side of the very short fuse that has the blue wire with red stripe. Does anyone have a list of what wires go to what? Someone messed up a lot of wires under the dash putting in a stereo. I thought about getting another wiring harness but I wouldn't know what went where. I have a Haynes manual but can't make heads or tails of their diagrams. Thanks for any help!!!!!
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Blue /red stripe wire is for Instument cluster lighting .
The fuse box doesn't run the fuel system.
Try this,it is a test for the Oil/Fuel/Temp gauges :
To check the gauges with the key off:
Take the connector for the oil pressure sending unit off
put a cotter pin it, now attach it to a good ground,go back and turn the key to ON > If the gauge pins to the high side the gauge is good.
Now do the same with the temp sending unit.
If the gauge DOESN'T pin, there is either something wrong with the gauge,wiring,or IC V reg.
To check the IC V.Reg with key ON:
Take a test light and attach it to the sending units wiring.
You should have a PULSING light.
If so, the IC V. reg is Okay.
If Not,either the wiring is bad or the V reg. is bad.
The IC V.reg is located on the back of the Instrument cluster.
The fuse box doesn't run the fuel system.
Try this,it is a test for the Oil/Fuel/Temp gauges :
To check the gauges with the key off:
Take the connector for the oil pressure sending unit off
put a cotter pin it, now attach it to a good ground,go back and turn the key to ON > If the gauge pins to the high side the gauge is good.
Now do the same with the temp sending unit.
If the gauge DOESN'T pin, there is either something wrong with the gauge,wiring,or IC V reg.
To check the IC V.Reg with key ON:
Take a test light and attach it to the sending units wiring.
You should have a PULSING light.
If so, the IC V. reg is Okay.
If Not,either the wiring is bad or the V reg. is bad.
The IC V.reg is located on the back of the Instrument cluster.
