Fuel Gauge Not Working

[JTG]

The fuel gauge is not working on my 68 Barracuda, the other three gauges that are housed within the same cluster work perfectly fine. The sending unit is NOS and the ground strap is new, the dash and instrument panel I just recently installed, all the nuts were tightened on the circuit board and the wire connectors are all snug. Is this a common problem and what should I be looking for.:dontknow:

 

[memike]

Double check your grounding clip on the fuel line at the gas tank and make sure you get a reading to ground on each end . JMO. and hope this is it :happy10:

 

[67Dart273]

This is a really simple circuit. Your circuit path is "from ground" through the ground clip as mentioned, -----through the sender----out the wire terminal on the sender---up the wire in the harness up to the dash----to one side of the gauge---through the gauge---to the instrument regulator.

If the other gauges are working, then the instrument regulator is working.

So yank the wire off the sender terminal and ground it, go up and turn on the key. the gauge should peg in short order. If it does, everthing from the sender wire end terminal up through the gauge is OK

So if this is so, do as suggested and check the ground on the sender/ tank.

If the gauge doesn't move when grounding the wire, then....

could be the wire from the tank, or even just the connector broken internally

Move up to the dash and ground the sender side of the gauge and see if the gauge moves.

If so, check the wire

If it does not move, make sure you have power to the opposite connection on the back of the dash. With a lamp, the power side will flash on/ off, with a meter will "pulse" up/ down IF you have an original style regulator. If you have a replacement "solid state" instrument regulator, it should show around 5V or so.

So if you get clear up to the dash, have 5V or pulsing on one side, ground the other, and no reading, then you have gauge problems.

 

[RedFish]

There are a couple of ways to check other than crawling under the car right away. You can locate the sender wire in the trunk, shove a shirt pin through the wire casing, Jumper the pin to chassis ground. Switch on should send fuel gauge pointer to extreme position in a smooth motion.
If that proves true, the problem is between the shirt pin and the tank.
If the the gauge doesn't move , try the same test at the harness connector behind the left kick panel.
At any point in that sender wire, an ohm meter should show somewhere between 73.0 and 9.6 ohms resistance depending on how much fuel is in the tank.

 

[JTG]

Thanks Guys, heading to the car tomorrow, and will try these things suggested.

 

[rosenavarro]

Sounds like a defective sending unit in the tank. The sending unit has a float carrying a resistance measurement to say what the fuel level. Sounds like the upper contact is fine, but as float down a little, there is no resistance, so no meter reading.