Fuel Guage issues

[crossmi]

So after troubleshooting as best I am able and also searching through posts I remain stumped by my 71 Newport's fuel gauge. When the car is started it slightly moves off empty, however doesn't reflect the fuel in the tank.
I replaced the sending unit as it was pretty much rusted out and seemed a likely culprit. Once reinstalled with a good ground...Nada....zip....
Next was the fuse box, nothing found there either...Now I'm not a class A Mechanic and it may be that I missed something, however I am pretty confident the install was proper.
So I thought I would post the question to the many mopar gurus and see what the consensus might be..
Thanks in advance

 

[MrMoparCHP]

On many Mopars of the era the instrument voltage regulator is in the fuel gauge, you may need to replace the fuel gauge.

Others the instrument voltage regulator is external and attached to the back of the dash panel.

The regulator would be my first guess. I'm not sure what style your car would have.


Alan

 

[commando1]

Is the ground clip on the line missing?

 

[crossmi]

It is not missing, today I removed the unit and reinstalled making sure everything was where it needed to be, I made sure the ground clip was firmly in place as well... When I turned the key, the gauge moved to slightly above empty, and no further. I tested the unit with a voltmeter and when the arm was moved the voltage corresponded to the sweep of the arm....The instrument voltage regulator is net on my hit list.

 

[MYSINBIN]

It is not missing, today I removed the unit and reinstalled making sure everything was where it needed to be, I made sure the ground clip was firmly in place as well... When I turned the key, the gauge moved to slightly above empty, and no further. I tested the unit with a voltmeter and when the arm was moved the voltage corresponded to the sweep of the arm....The instrument voltage regulator is net on my hit list.

Not to poke the bear, but do you have any idea how much fuel is in the tank?

And are you sure that the brass float is good/new?

I just replaced the sending unit in the black 2DHT. I put 5 gallons in and it barely moved the needle on the gauge. Went and filled up and it read an eighth below full. It consistently reads that way at each fill up.

Hope the input helps.

John

 

[1Fury1]

Just went through the same thing. Bench tested the sender and it went through the resistance range as normal. Replaced the leaking copper float with a plastic one. Double checked the ground as indicated above and even ran a separate wire. Still sitting on E. Then pulled the gauge cluster out of the dash ( disconnect your negative battery lead there is a direct connection to the amp gauge).
Reconnected the battery and as I moved the gauge cluster around with wires attached the gas gauge came up and then went back down. I found that all of the nuts on the back that make contact with the printed circuit board was loose. Snugged them all up with a nut driver, reinstalled, and voila 3/4 tank.

 

[crossmi]

Ill be sure to check all of these items...thanks for all the ideas..In theory it shouldnt be that difficult to troubleshoot...In theory.....

 

[MrMoparCHP]

A general tip to anybody who has not had the instrument cluster out o the car. Just because take it out, remove the circuit board and take a pencil eraser to all the points that have nuts or light sockets on them, a little emery paper on the pins.

That alone will make a big difference in the cluster lighting and eliminate the cluster as a possible in troubleshooting.


Alan

 

[live4theking]

take a pencil eraser to all the points that have nuts or light sockets on them, a little emery paper on the pins.
Alan

Reminds me of slot car tracks...

 

[440_Magnum]

A general tip to anybody who has not had the instrument cluster out o the car. Just because take it out, remove the circuit board and take a pencil eraser to all the points that have nuts or light sockets on them, a little emery paper on the pins.

That alone will make a big difference in the cluster lighting and eliminate the cluster as a possible in troubleshooting.
Alan

I agree. And I'd also add, invest in a little tub of Caig DeOxit CP grease, and (VERY sparingly and carefully) coat every contact and exposed "pad" on the dash circuit board. Also works great for the infamously flaky bulkhead connectors. The CP type grease has copper particles to make better contact than you get with either their "NP" (no particle) grease or with parts-store dielectric grease. But that's why you need to go easy with it and not bridge connections with the grease. It won't create short circuits and start a fire or anything, but no need to be sloppy with it and it is expensive. The little 28 gram thimble of it has lasted me several years.

Amazon product ASIN B00880RTPI

 

[rags]

had the same problem with the loose nuts on my '65 instrument cluster. circuit to sender can be checked old school test light connected to GOOD ground. disconnect wire from sender, hook to hot side of test light. light should flash with key on. confirms voltage regulator in dash, fuel gauge, and circuit through to sender. good luck, SG