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Old 05-19-2003, 10:46 PM   #1
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Default gas gauge always reading full

Ok, I just noticed something else wierd about my riv.. When I first bought the thing it only said 1/4 of a tank of gas. As I drove down the road the gas gauge slowly krept up to a full tank and now it is staying there. What is going on? There aren't any Riviera boards online so there isn't anyone to ask but here. :( I hope somebody can help though! It sucks having the gauge read a full tank but having less than a 1/4 tank of gas. :(

Don't know if this makes any differnece, but the car had been sitting since around October since it was last driven..
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Old 05-20-2003, 12:42 PM   #2
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Default Re: gas gauge always reading full

Originally Posted by Custom88
Ok, I just noticed something else wierd about my riv.. When I first bought the thing it only said 1/4 of a tank of gas.
Okay, first of all, how much gas _is_ in the car? You sure that the 1/4 reading is correct and the Full reading is wrong? Just because it'* been parked for months doesn't mean it didn't have a full tank at the time.

If the other gauges are correct and only the fuel gauge is suspect, check the wiring back to the sending unit at the tank. (Current in that wire runs _from_ the dashboard _to_ the tank, with a rheostat in the tank sending unit controlling the resistance to the ground connection, which controls the gauge reading.)

I think the usual GM color code for the gas tank sending unit in the rear wiring harness is light tan. Look for it in a bundle with Yellow (left brake/turn), Green (right brake/turn), Brown (taillight/markers) and whatever the Backup color is (Light green?).

If you can find an in-line connector for it somewhere between the tank and the rear bumper, try unplugging it there and see if the gas gauge reading changes. The needle should peg on either Empty or Full when you do so (I forget which way). Also try grounding that wire to see if the needle then pegs on the opposite end of the gauge.

If there'* no reaction on the gauge at all, either the sending unit wire is broken (check it for voltage) or the field windings of the gauge itself are dead.

Anyhow, muck around a little and see what you find; get back to us if you're still stuck.
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