fuel gauge is still not accurate


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Old 03-13-07, 08:45 AM
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fuel gauge is still not accurate

I Have A '99 Gmc Sierra, 5.3l 4wd Ext Cab Pickup. My Fuel Gauge Became Erratic And Not Accurate. I Checked The Fuel Pump And It Was Fine. I Replaced The Sending Unit With A New Gm Unit And Now The Fuel Gauge Is Still Not Accurate, But It Is Not Erratic. Origianlly The Fuel Gauge Pegged All The Way Past The Full Mark So I Checked The Wiring To Make Sure It Was Not Shorted Out Somewhere And Found Nothing. I Removed The Fuel Pump Assembly From The Tank And Manually Moved The Float Up And Down To See If The Gauge Would Respond. It Did Respond. I Reassemble The Fuel Tank And Pump Assembly, Put The Bed Back On And The Fuel Gauge Hand Stayed Past The Full Mark For Quite A While Then It Gradually Began To Drop As Fuel Was Used From The Tank. It's Now Staying At Just Above The Half Full Mark. My Problem Is That I Know There's Less Fuel In The Tank Than The Fuel Gauge Shows And I Don't Know Why. Please Help.
 
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Old 03-13-07, 10:18 AM
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Did you replace the fuel gasket that goes around the pump and the tank mating surfaces? If this gasket is bad, there will be a bad electrical bonding between the tank and the sending/pump unit. If this is all good, then you might have a actual gauge problem.
 
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Old 03-13-07, 12:55 PM
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I have a 99 silverado with the 5.3 and ever since I got it the gauge would go weel past full when you fill it up. The gauge would stay there until I put about about 100 miles on the truck. Then it would start dropping faster and faster. The closer its gets to empty the faster the needle moves.
 
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Old 03-13-07, 02:05 PM
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A gas gauge sending unit has a float at the end of an arm, this regulates the gauge. It can get bent during installation thus changing the accuracy of the gauge.

When I mis diagnosed my jeep having a fuel pump problem [it was actually the connector] I removed and installed my pump a couple of times. My once accurate gauge now doesn't let the fuel light come on until it is almost out of gas [1 quart or less ] I know how to fix it but.........
 
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Old 03-13-07, 03:43 PM
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Marksr is right. These sending unit arms do get bent.

Also, on a different note, don't drive long at all with gas tank below 1/4. Usually this means the fuel pump is not submerged in fuel resulting in overheating of the pump and eventual failure.
 
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Old 04-17-07, 08:12 PM
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Red face Fuel Gauge

Im Having The Same Exact Problem With My 94 Jimmy, Have U Found A Cure??
 
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Old 04-23-07, 07:58 AM
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On my 89' S10 my fuel gauge when it gets in the reserve area its time to refuel right away, never was like that before but do to my do it yourself skills I screwed something up. And after reading these posts I figured that my float may have something to do with this, and it might just be that your float may have bent when you were removing it or installing. Also check that all bolts are nicely secured all around the tank.
 
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Old 04-23-07, 11:22 PM
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Fuel gauge

I have an 1988 K2500 4x4 and my fuel gage messes up all the time to. It reads right then all of a sudden it drops down to 1/4 tank or so then it will come back after awhile and read right. Any ideas on this one
 
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Old 04-24-07, 02:20 AM
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Smile fuel gauge

Just a thought but did you check to make sure there aren't any dents in the tank.
 
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Old 04-24-07, 06:23 AM
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Also some tanks [sending unit] are prone to mis reading. My wife's merc is bad to read towards empty going up hill and towards full when going down hill. The strange thing is it takes a 1/2 mile or more on level roads for it to go back to an accurate reading.
 
 

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