Technical New Fuel gauge buried past “Full” -1954 3100

Upon turning key for first time to “on”position, the new 12v reproduction gauge buried itself off the gauge past “Full”. It does have the cardboard insulation between the housing and the bolts that attach it to the housing. The wires are no where near each other so aren’t shorting out. The F side is to gauge power, the E side is to the sender in the tank.

Is there supposed to be an internal insulator between the gauge inside the housing and the housing itself? Or is it supposed to be bolted right to it? Because that’s what I did.

is there anything I’m doing wrong? I suppose the sender could’ve sh*t the bed in the meantime. It didn’t read absolutely correctly with the old 6v gauge but I’d assumed it’s because I think there had been a resistor put in to save it when was switched to 12v generator years ago. Could be a faulty new gauge as well?

Thanks in advance. I owe a lot to y’all.

Chad

 

Sending unit in the tank. What condition is it in?

 

What happens if you disconnect the sender wire? Based on your avatar I'm guessing you are working on a GM product. Many of those used balanced coil gauges. On most an open sender circuit would cause the gauge to read full and a grounded sender circuit would cause it to read empty. What does the aftermarket gauge manufacturer say?

 

Great question. It isn’t new that’s for sure. Anyone know how to get at them in these trucks? No access under the truck that I can see, and nothing under the bench seat either.

 

So unhook the sender wire on the back of the gauge.

 

It’s a reproduction gauge and yep, it’s a 1954 Chevy 3100. It’s a gauge that goes in the original gauge cluster to look like original.

I believe I bought it from Classic Parts, or another outlet like them- don’t recall. There was no instructions at all that came with it. And when I called them, they didn’t have a tech department.

later today I’ll check what you suggest

 

FYI, this is the part.
http://www.classicpartsusa.com/prod...MI-ai0oPeM7gIVIgnnCh0ySA09EAQYBCABEgLB8fD_BwE

 

Nothing like the original. I'd opt to not momentarily ground out sending wire to see if it goes to empty. Do you still have original gauge?

 

That should be a 30 ohm gauge to go with your 30 ohm sending unit if you have the stock tank behind the seat. If the filler neck is still in the right side of the cab behind the door the gas tank is behind the seat back and you can get to it by removing the seat back from the seat frame.

If you scroll down the page here to the tenth page 54truckwiring.pdf (oldcarmanualproject.com)
If you scroll to the bottom page the diagram of hooking up the gauge is shown.

Possible causes are
Tank unit shorted.
Wire between units disconnected or broken
High resistance in wire between units
Float stuck in full position.

 

There's threads on here about making a fuel gauge tester or buy a good used on on eBay (I did). Use an ohm meter to see the readings on your sending unit (have to remove it and move the arm) and then use a gauge tester to check the gauge. I had a repo sending unit that turned out to be the wrong ohms for my stock gauge on my TF, so you can't trust anything repo.

 

Float having a pinhole would allow fuel to fill the float - ergo no longer a float. No buoyancy. Had the same problem with my 66 Mustang. Hope that helps

 

I think if the float was not floating it would always read empty. His reads past full.

 

disconnect the sender wire from the gauge. Measure the resistance on the sender wire, relative to ground. Tell us how many ohms see on the meter.

 

Sorry about the late response, been doing errands all day.

Disconnected the pink wire that goes to sender. Turned key on, no change. Tapped test light hooked on ground to terminal that goes to sender, stays buried.

might be faulty? No movement, can’t even see the needle.

lots of gremlins. Tested 7-wire signal stalk indicator light. Ground is good, flasher can is good. The light on the end of the new stalk is dead. I can live without it though.

I also rigged up a test lead to check the low beams and that is good. Turns out the dimmer switch has gone south.

Momma said there’d be days like this

 

If the gauge is designed to work with the original sender, then it should have indicated close to empty when you did this, assuming the gauge is good, and getting power and ground.

 

had that problem in a '47 tudor converted to 12v...
i ran a momentary switch, push it in and take a look... let go it goes back to sleep...
i used the 6v gauges in the 12v system for two years... no problem.

 

Yup. Didn’t move nada, zero, zilch. I think I’m dealing with a dead gauge out of the box. Was probably manufactured overseas and has had a long history of being jostled around by now and is probably not gonna work.

The pain of it is that these clusters are not easily accessible anyway. The temp gauge is a hard wire and they don’t come out the front, they only fall out the back. So I’d have to pry it apart again and replace it, even if they’re willing to send a replacement, which most outlets will not if electrical parts have been installed.
I’m just wondering if I did something wrong to kill it.

 

Op's new gauge is for 12 volts. Tank sending unit doesn't care what voltage.

 

So you are saying that the needle is on F no matter if the key is on or off?

If you hook a multi meter to the wire that you took off the gauge that goes to the sender an connect your multi meter to it and ground you should get somewhere between a 0 and 30 ohm reading. This is what Jim was suggesting.