Gas Gauge Issues

[dobie]

Ever since I've had my car up and running, the gas gauge hasn't worked properly. It will never read more than 1/2 tank, even on a full tank. I had put in a new 3/8" sending unit bought from Herb's a few years ago, thinking that was the problem. Even still the gauge wouldn't work. At this point my uncle was (still is) convinced that it was the gauge itself which wasn't right.

At Carlisle I bought a new gas tank and installed it last Monday. While the tank and sending unit were out we tried things. Surprisingly, the gauge read accurately as the float was moved. Once back in, of course it's not right again. IMO, something's up with the float/sending unit. My uncle still thinks it may be a gauge issue. Then again, he's not pleased with my ground strap. I bought a repop one with the non-spring clamps. According to him, the originals had jaws which were "springy" and therefore he feels it may be a grounding issue.

So, what say the experts here? Any ideas on what's causing the malfunction with the gauge readings? Also, does someone make a correct fuel tank ground strap?

Thanks!

:cheers:

 

[ACME A12]

Steve:

What do the repop grounding straps look like if they don't have the jaws...? Just curious...

Have you tried adjusting (bending) the pivot arm the float attaches to? If the gauge read accurately when you manipulated it while out of the tank then it seems like the guage has proven it's not the culprit and there's not likely a grounding issue either. Sounds like the arm needs to be tweaked to me...

Sorry I missed you at Carlisle...

:jester:
Ray

 

[Hoosier Bird]

 

[Basketcase]

I had my '68 Charger for 18 years, Freebird for.......7, and neither had the ground strap on the tank, and both gauges worked fine, so I'd say the grounding isn't that important. My thoughts would be to pull the tank, and set it up by the car. run a wire from the sender wire to the tank. Fill the tank with water(?) and see where the gauge is. Then you can pull the sender and tweak it as needed.

 

[dobie]

Steve:

What do the repop grounding straps look like if they don't have the jaws...? Just curious...

Have you tried adjusting (bending) the pivot arm the float attaches to? If the gauge read accurately when you manipulated it while out of the tank then it seems like the guage has proven it's not the culprit and there's not likely a grounding issue either. Sounds like the arm needs to be tweaked to me...

Sorry I missed you at Carlisle...

:jester:
Ray

Well, they have jaws, just not "spring loaded" as apparently the originals were. Here's a pic that closely resembles mine.

 

[dobie]

Thanks for the help. I agree that it's more of a float/sending unit issue than anything else.

:cheers:

 

[Basketcase]

Hey Steve I have a couple spare gauges if need be.

 

[dobie]

thanks for the offer! i actually have at least one spare in another panel somewhere.

 

[A12]

From the repair manual "trouble-shooting" it sounds like a poor ground.......I think I have the same problem too. I'll let you know what I find out on my rr. Here are a few pages from the shop manual

1

 

[A12]

2

 

[A12]

3

 

[moparstuart]

3

 

[69hemibeep]

We did a survey on the old runner site and every one of use was a 1/4 tank low. And it was a pretty good number of members :huh:

 

[Hoosier Bird]

 

[dobie]

Wow. Very interesting.

I'll have to try for a better ground then. Any ideas?

Another question: What is this "Tester C-3826?" It's obviously a test meter or something, but can these be bought today? Or, is there something similar which works just the same?

Thanks!!

 

[69hemibeep]

Wow. Very interesting.

I'll have to try for a better ground then. Any ideas?

Another question: What is this "Tester C-3826?" It's obviously a test meter or something, but can these be bought today? Or, is there something similar which works just the same?

Thanks!!

Its most likely an OHM meter, thats how I tested mine but its not going to see gas for a little while for the supreme test.

 

[dobie]

In reading the attached files, it appears that you can hook up this tester and set it to a specific setting. The gauge then should read Full. I would guess then that by accomplishing that, one can reasonably assume that the gauge is working properly.

Also, it seems that a higher level of resistance is needed to put the gauge at Empty. A ground issue seems much more probable the further I think of this. Although, could a float/float arm be out of whack enough to always read 1/2 or below?

 

[69hemibeep]

In reading the attached files, it appears that you can hook up this tester and set it to a specific setting. The gauge then should read Full. I would guess then that by accomplishing that, one can reasonably assume that the gauge is working properly.

Also, it seems that a higher level of resistance is needed to put the gauge at Empty. A ground issue seems much more probable the further I think of this. Although, could a float/float arm be out of whack enough to always read 1/2 or below?

Another issue is you cant tell where the top or bottom of the tank is when its out on the bench :cheers: Oh its 10 ohms full and 73 empty

 

[dobie]

So here's another dumb question then: How could I properly ground this thing to see if that takes care of the problem?

 

[69hemibeep]

So here's another dumb question then: How could I properly ground this thing to see if that takes care of the problem?

Use a toothy clip with a wire from the unit to a good looking ground on the car like a bumper.