1966 Plymouth Valiant Signet Fuel Gauge Cavitation

[SirFartsALot]

I have just got my car back and it it running like a champ with just one little problem.
Before I picked the car up a couple of days ago the car was bone dry on the gas and when I filled it up the gas gauge responded just like it was to. It took an additional hour or so for them to get the temp gauge to work right and they delivered the car to my house.

I am drained financially for a while and was wondering if there was anything that I could pour in the tank that could take care of the cavitation shown in the gauge?

 

[KitCarlson]

If the tank is full, and the cavitation means it shows low, then the problem is likely loss of electrical connection. The first place to look is the ground clip at the tank, that clips to the fuel line, jumpering the short hose. Without the jumper, the tank is often electrically insulated from body. It should be an easy fix, perhaps take it back, they might do it as a Christmas gift.

 

[67Dart273]

Hi Dave



OP you are going to have to explain what you mean by "cavitation?" Do you mean the gauge is intermittent?

WHAT IS IT that you are working on, year, model?

You can download FREE shop manuals at MyMopar. Some of them there are due to the efforts of guys HERE

MyMopar - Mopar Forums & Information - MyMopar Tools/Reference

The gauge system is a "simple" series resistance circuit.....as Dave said........

From the sender ground.......and you cannot depend on the "connection" from sender.......to tank............to body
So the factory had a ground clip jumper the connector hose. "In a pinch" you can clamp a wire around the nipple and run it to ground

Next, the sender CONNECTOR which might be loose/ corroded, even broken inside, "work" it on/ off the stud a few times to scrub it clean.

The wire goes up to the left kick panel harness connector, you can separate that and check it there with an ohmeter and see if you "made it" that far. "Work" that connector in/ out a few times

From there it goes to the cluster PC board connector and THOSE have their share of intermittent problems. There's an old thread here details PC board connector "pin" repair.

Then it goes to one stud of the gauge AND THOSE NUTS get loose and corroded. You must loosen/ tighten them, and think about replacing them, they were originally "stamped" steel speed nuts

Then from the other gauge stud (also a nut!!) the trace goes to the instrument limiter / regulator. If the temp gauge works OK, then that part of it is likely OK as well