I think I fixed my fuel level sender!!

C

Crazi

Why Try...
Joined
May 26, 2001
I was changing the gas tank and since my gauge wouldn't go past half tank or below 1/4, I decided to try and fix the sender. It was broke anyway.

What I did was open the crimps that hold the sender portion on and examine the wiper and resistor wire. It looked good and the wire wasn't broken but I bent the copper spring portion that makes the wiper contact the wire out a bit anyway to increase the tension. Then put it back together and it didn't work.

Then I moved the two pieces together to make sure they were together all the way and it would work intermittently! I got about 4-6 ohms at empty and about 90+ at full. Then I took the halves back apart and used a knife to scrape both halves where they touch each other. Put it back together and it was working alot less intermittently.

Took it back apart and scraped it more. Put it back together and....It Works!!! Even increase in resistance from empty to full! Whether it will work when I fill the tank back up remains to be seen.

What I figured out is that the outer portion needs the shell to be grounded. I assume that after a while the two halves lose a good ground with each other and the gauge stops getting a good reading. If your wires that the sender wipes across are broken, you are screwed. If you break them in the process, you are screwed. So be careful!

I also toyed with the idea of attaching a ground wire to the shell portion of the sender. If you can do this and your wires aren't broken, you should get the same results.

Sorry this is so long, just wanted to share my potential success and give back to the board if this works.
 
It's great when you actually make something better than it was...I usually finish breaking the object of my attention! :)
 
Forgot to reply to this...

But it ain't fixed. :mad:

How do I get the proper range when I moved the sender with the multi meter hooked up but the gauge just won't read right? Maybe I should try an aftermarket gauge???:confused:
 
What I've been told by friends that work for GM is that the gauge itself can go bad. The gauge is also no longer in GM's system. I have heard that GM had an obsolete parts division, but I have not been able to find it to get a new guage myself. I have already replaced the sender with a new unit (which reads correctly on a volt meter), but the guage is still incorrect (floats badly). I guess its time to install the GNX dash I bought.
 
Rumor has it that the gauge unit was used on just about anything and everything that came off the line at GM for many years. Don't know for sure but it sure would be worth checking out. If it's true there is an unlimited supply of donor cars out there! Sure looks like a retro part to me.
 
The problem with the stock fuel gauges isn't in the sender (generally). It's in the gauge. When you get at the gauge (from the front), you'll see it just plugs into the dash cluster with a couple of pins into sockets.
What happens is corrosion builds up on these two pins and sockets, causing resistance changes, etc.

The thing to do is pull the gauge out, and emory cloth those two pins nice and clean, and clean out the sockets as best you can.
You'll get a good working gauge then (unless you've damaged something on the sending unit).
 
Thank Dave!! I'll try that first.

I will know how much fuel is in my tank after all. I went to add gas the other day cause it said 1/4 and the damn thing took about 8 bucks. It still only read about 3/4 but it will go under the dash if I disconnect the sender.
 
Thanks Dave,

Finally got around to cleaning the contacts ( thoughts it would be a PITA to take the dash apart) and it works!!

Took all of 15 minutes and seven 7/32" screws...
 
You're welcome.

It's always the first thing I suggest when there's a question about the accuracy of the fuel gauge. Simply because the sending units hardly ever go bad. When they do, you'll know it.

However the gauges always will read with varying degrees of inacuraccy as time passes. The corrosion on the contacts is the culprit. It only takes a few ohms difference to make it look bad.
 
TurboDave said:
You're welcome.

It's always the first thing I suggest when there's a question about the accuracy of the fuel gauge. Simply because the sending units hardly ever go bad. When they do, you'll know it.

However the gauges always will read with varying degrees of inacuraccy as time passes. The corrosion on the contacts is the culprit. It only takes a few ohms difference to make it look bad.
Click to expand...
Does this hold true for the Digital Display as well, my gauge reads Full all the time. Just had tank cleaned, new pump and sending unit installed, I'm wondering if anyone knows if there is a different sending unit for the Digital Dash? The shop I took it to didn't know it was digital and I have a feeling they put an Analog Sending unit in it. It's nice to always have a full tank but this crap is getting old.
 
going by memory here as it's been a couple months since Ive done this but it will make your gauge much more accurate-er....


If you look at the ground path on the sender, you'll notice the float arm supplys the signal for the adjustable resistor. It gets it's ground from touching the pivot points it passes through. One side is a well grounded flange (maybe), the other side is the 'shell' that's grounded only by a weak crimp joint. Needless to say, I'm amazed they ever worked at all, much less as well as they do.

The trick is to solder a wire to the float arm and run it to the sender body. That way the arm can start with a positive ground signal.


I did that mod the last time I had my tank down. When I filled up, my gauge went to 'full' in about 1/10th the normal time.


Make sure there are no cold solder joints where the tube passes through the hangar flange too. That joint also supplies grounding for the pump.
 
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