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Guel gauge acting up


bryanb

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Searched for fuel gauge problems, and i did find somethings to check. All of them more work than im currently in the mood for :)

But this one is a bit specific, so I thought I'd try a new thread on it anyway.

A few years ago I replaced the fuel level float, sender, and pump as part of a kit from rockauto.com. The gauge was always on E prior. The metal float had spring a leak, and was at the bottom of the tank. New one is plastic, I believe.

Worked great for 2-3 years.

Now, all of the sudden a couple days ago its begun to act very weird.
an Example:

Starting the truck this morning, its reads way full! Then after a bit, I shut engine off, and restarted. Then it goes to near empty. and stays there.

After work, started it again. and it goes to way full, and then slowly came down to half. Then slowly came down to near empty.

According to the trip odometer, I should be between 1/4 and 1/2 tank.

I've read that the gauge is basically an ohm meter. I wonder if there is a short or a place where the wire is all of the sudden chaffing?

Thoughts?

thanks.
 


RayInStl

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Well, that didn't work. Let's try something else!
There's a circuit on the back of the gauge cluster that's known to go bad. It's supposed to stop the needle of the fuel gauge from fluctuating because of fuel sloshing around. I imagine yours is on it's way out. They usually get stuck on full when the circuit dies completely.

You can bypass the circuit to test it (or just leave it bypassed) by doing the following:

- Remove your cluster
- Looking at the back of the cluster, you should see a square circuit board clipped into the back of the cluster kinda like a card. It just unclips.
- On the board, locate the metal input/output pins. There will be a group of two pins and then a group of three.
- Place a piece of electrical tape over the group of 3 pins.
- Take a small length of wire and jump the other two pins so that they are now connected by the wire.
- Clip the circuit back into the cluster
- Reinstall the cluster

The hardest part of that whole process is removing the cluster.

If you gauge works correctly now, then the circuit is the problem. You can leave it like this or get a new circuit. If you leave the bypass in place, the gauge will move some when you hit bumps, stop, accelerate, make turns, or do anything else that might make the gas in the take slosh around.
 

RayInStl

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Well, that didn't work. Let's try something else!
If that doesn't fix it, either your sender is going bad or you have a damaged signal wire between the tank and your cluster.
 

bryanb

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Did another search today and found my old forum post! And the fluctuation and odd behavior has stabilized somewhat.

Every time, it goes to full-full, and then slowly comes down to empty.

I located the yellow/ white wire in the engine bay,coming from the under the frame, and gas tank. Checking the resistance, I get 15 Megaohms. seems odd.

Got dark before tying with ignition on, I think that'll make a difference, in hindsight?
Failing that, I'll have to pop the bed and check from the tank. The instrument panel ain't coming off. Can't get to the gear indicator cable to pull it. Really don't want to pull it from the tranny.
 
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