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Thread: Gas Gauge Problems

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    Default Gas Gauge Problems

    I know several 80's dodge trucks that the gas gauge doesnt work and the one I'm getting ready to start working on is one of them and was wondering if it was commonly a in tank issue or a cluster/gauge issue.

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    Senior Member 70DartMike's Avatar
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    I don't know if it's the same, but in my 75 Ford, the sending wire was broken behind the dash, and the sending unit itself was toast. I replaced the unit, and the gauge still didn't work. What I discovered was the float had a pin hole in it, and wouldn't float anymore. Swapped the float, and it works.
    1970 Dodge Dart Custom, 1967 Plymouth Barracuda, 1965 Fargo W300, 1966 Dodge W300, 1969 Fargo W100, 1965 Plymouth Valiant, 1962 Dodge Dart, 1975 Ford F250 Highboy, 1975 Ford F250 CS, 1975 Chevy G20 camper

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    Quote Originally Posted by 70DartMike View Post
    I don't know if it's the same, but in my 75 Ford, the sending wire was broken behind the dash, and the sending unit itself was toast. I replaced the unit, and the gauge still didn't work. What I discovered was the float had a pin hole in it, and wouldn't float anymore. Swapped the float, and it works.
    Sounds to me like while I have the column out anyway I could test the gauge itself im assuming by grounding it correct? And if it works drop the tank and replace the float and unit.

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    Yeah, the brass float on the earlier models is the #1 most common cause but if yours is the one for the plastic tank, it's probably the sender. #2 would be the sender itself, If all the other gauges work....#3 would be the circuit board or connection on the back of the dash, and #4 would be the gauge itself. If the oil pressure and temp gauges don't work either, then the most likely problem is the dash voltage limiter. If you need or want to replace that part, get one of the solid state ones that are on the market now. You can do a simple test to see if it's a sender problem or not. Pull the power wire off the sender and jump that power wire to ground. Then turn the key to the on position and see if the gauge now starts to come up. If it does, turn the key right back off again as you don't want to overheat the gauge. If the gauge comes up, there is something in the tank that isn't working right....float, sender, or ground connection. If the gauge doesn't move when you ground the sender wire, then it's a wiring, circuit board, connection, or gauge problem. Once you get that straightened out, you can do the sender test again. I had one truck where every single part of the system was bad except for the wiring harness. I had to replace the sender (with a new float), repair the sender ground wire, new circuit board, and new gauge.

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    Thanks, I'll have to check it all I guess because dad had one of the three gauge pods for the temp,oil pressure, and voltage hooked up so I know the voltage and the temp are disabled. I'm prolly going to drop the tank anyway because it has been sitting for about five years and I dont think that gas would run very well now lol.

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    Senior Member bear's Avatar
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    Nine time's out of ten the fuel gauge problem in these truck's is a bad ground or the wire going from the sending unit ( gas tank ) to the gauge . To check , Ground out the wire at the sending unit and see if your gauge move's ( with the key on ) . If it does then check to make shure the sending unit has a proper ground . ..... Quick question though . If your column is out of the truck then how are you powering up your instraments ? Your key has to be on for the gauge to work .

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    Quote Originally Posted by bear View Post
    Nine time's out of ten the fuel gauge problem in these truck's is a bad ground or the wire going from the sending unit ( gas tank ) to the gauge . To check , Ground out the wire at the sending unit and see if your gauge move's ( with the key on ) . If it does then check to make shure the sending unit has a proper ground . ..... Quick question though . If your column is out of the truck then how are you powering up your instraments ? Your key has to be on for the gauge to work .

    I said that wrong lol right now the truck has an automatic column in it from back when dad switched it from 4 speed to a 904 he had and it has been sitting for several years now and I am planning on starting working on it next month. I'm pretty sure I still have a known good cluster out of a truck I parted out so I was going to toss it in when I swapped columns and then test it with the new cluster and column and if that didnt fix it I would check the rest when I drop the tank if I have to.

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    You can test the gauges themselves with an ohmeter if you have the cluster out. Just see if you have continuity across the two terminals of each gauge. You can also test them by powering up the voltage limiter and grounding the sending unit terminal of each gauge to see if they work. Just don't let the guages peg or you risk damaging them. I like to run the ground wire through a test light. That way the gauge comes up slowly and there is no risk of burn-out. Unless you have a test light with a lot of resistance, the guage probably won't go past 1/4 of it's travel but that's all you really need for a test. Those cheapie ice pick test lights work good for this kind of test.

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