Fuel gauge reading ????'s

[dickeymoore]

I have a 1980 monte carlo and the full gauge use to read almost full when I fill up but now it reads just under half tank when full,should I look for something else or is it the senfing unit inside the gas tank?Thanks

 

[popeye1978]

My initial guess is the instrument panel contacts for the gauge, similar to what was discussed in Voltage drop on gauge

Did this occur following your first fill-up after winter storage or over time has the gauge -- after each fill-up -- been gradually indicating less-and-less?

 

[fleming442]

is it a factory gauge?

 

[dickeymoore]

Factory gauge been doing it every since I bought the car about 3 years ago but now it's just at about half way on fill ups

 

[bracketchev1221]

Well, you can disconnect the wiring at the tank and ground it and it should read full. That is one test, but basically you either have to look at the gauge or the sender unfortunately. My 70 SS has a brand new sender and it only reads half of what it should. I checked the gauge with another sender I had and it did the same. SO now its on to the dash.

 

[dickeymoore]

So if I ground it and it reads full is it the sending unit?

 

[bracketchev1221]

So if I ground it and it reads full is it the sending unit?

Not really. It just means the gauge moves freely and that the wiring between the points is good.

 

[fleming442]

I thought open wiring was Full and grounded was Empty (pink wire)......🤔

 

[TURNA]

Shake the cluster see what happens

 

[bracketchev1221]

I thought open wiring was Full and grounded was Empty (pink wire)......🤔

You're right I'm backwards.