Best way to test non-working fuel gauge

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poisondart64

poisondart64

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What is the best way to test a fuel gauge on a 64 Dart? Gauge has not worked since I got the car (I just keep her topped off all the time....). Want to see if it is the gauge or the sending unit.

Thanks for any words of wisdom you can offer.:sign7:
 
Correct, ground the wire at the tank (a, alligator clip lead works great). Turn ignition on, gauge should read "Full". Actually, it should go to top of scale past full. This means the gauge is OK, and the sender is faulty or the connections are bad. Most times bad gas gauges are caused by dirty connections back at the tank. No big surprise as they are exposed under the car.

If you ground the wire and the gauge does not move, check for voltage at the wire. Should be about 5v. The sending unit in the tank should be about 10 ohms full, 73 ohms empty. If the resistance values are way out of this range, replace the sending unit/pickup assembly.

If you ground the wire and the gauge reads less than full you instrument cluster voltage regulator is faulty. Also a common issue. This means your temp gauge is reading low too.
 
C130 Chief said:
Correct, ground the wire at the tank (a, alligator clip lead works great). Turn ignition on, gauge should read "Full". Actually, it should go to top of scale past full. This means the gauge is OK, and the sender is faulty or the connections are bad. Most times bad gas gauges are caused by dirty connections back at the tank. No big surprise as they are exposed under the car.

If you ground the wire and the gauge does not move, check for voltage at the wire. Should be about 5v. The sending unit in the tank should be about 10 ohms full, 73 ohms empty. If the resistance values are way out of this range, replace the sending unit/pickup assembly.

If you ground the wire and the gauge reads less than full you instrument cluster voltage regulator is faulty. Also a common issue. This means your temp gauge is reading low too.
Click to expand...

Just want to add the instrument voltage regulator (IVR) is built into the fuel gauge on this car

Brian
 
C130 Chief said:
If you ground the wire and the gauge does not move, check for voltage at the wire. Should be about 5v.
Click to expand...
That would be a pulsating 12v that averages out to around 5v.
Seeing the intermittent 12v on your meter can be confusing if you're expecting a steady 5v.
You can also check it with a test light - it should go off and on to a steady beat.
 
The ground strap on the fuel line at the tank is sometimes the problem. As I understand it the tank needs to be grounded by way of this bridge on the line that bridges the rubber hose.
 
If the sending unit has never been pulled out you may also find the filter screen on the end of the pickup tube is gone. While you're at it also be sure to replace the short piece of 5/16 gas hose and clamps.
 
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