Fuel gauge not working 88 crew r20

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30backs

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My fuel gauge went to pass full today I have never had a problem before any ideas?
 

bucket

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Could be a number of things. Find the pink wire going to the sender in the tank and ground it out when the ignition is on. If the gauge goes to empty, then unbolt the ground wire from the frame and clean the connection. If the gauge still doesn't work it's probably a bad sending unit.
 

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Ok thanks for all info I will try this.
 

chengny

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My fuel gauge went to past full today

I can't speak for anyone else - but for any C/K I have owned - that would be normal operation. If the gas tank is filled all the way up, the needle on the gauge goes well over the "F" mark - maybe an 1/8" past it.

It stays there for miles and miles. Then, when it finally comes off that pegged position, it drops at the expected rate.
 

bucket

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My fuel gauge went to past full today

I can't speak for anyone else - but for any C/K I have owned - that would be normal operation. If the gas tank is filled all the way up, the needle on the gauge goes well over the "F" mark - maybe an 1/8" past it.

It stays there for miles and miles. Then, when it finally comes off that pegged position, it drops at the expected rate.

That does seem to be true for all. But when there's a bad wire or something, they go WAY past full and just don't work at all. Although the left tank on my '79 does read WAY past full when you fill it, it does eventually start working, but is empty at 1/8 tank.
 

89Suburban

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Mine does the same thing, stays past full for a few days then starts to drop. It was at the half way mark and took 93 phucking dollars to fill up. And when that needle hits "E", you are definitely empty.
 

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Mine was on half a tank and I made a right turn and it went way past full so it must be a wire. I wished it would warm up do I could look at it.
 

Boone83K10

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It is a bad ground, I am 100% certain. Check the wire on top of the tank..if it's off, push it back on. Check the other end of that wire, it attaches to the frame. Clean that and see if it works. Check back after that.
 

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Ok tried messing with the ground wire tonight with no luck I remove it from rail and cleaned it and reinstalled any ideas?
 

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Ok so I had a buddy of mine ohm out the fuel sender and he said it was bad . But on my way home today I hit a bump and the Gauge started moving I'm not sure if it was reading correctly but it was all over the place any ideas?
 

Boone83K10

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Did you check the ground wire on top off the tank.
 

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Yes I checked the ground and it appears to be good.if the sender was bad gauge wouldn't move at all correct?
 

chengny

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Check the pink wire. It runs from the dash, through the firewall, along the frame rail and attaches to the sender head.

Look for breaks in the insulation which might indicate a intermitent connection within the wire. A broken/loose connection on the hot wire (pink) will peg the gas gauge to FULL. Just like a bad ground wire between the sender head and frame will.

With the gas gauge, higher current flow through the sensing circuit (pink wire, variable resisitance sender unit & ground from sender to frame) will drive the needle down.

If anything slows this flow the needle will move towards FULL. If the circuit is completely broken, the needle pegs HIGH.

The diagnostic chart:



BTW - was the truck ever equipped with a dual tank set up?
 

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