Fuel Gauge Reading Past Full!!! HELP

[dustin1123]

i have a 76 Scottsdale 10 and the fuel gauge is reading at 3 o'clock i have replaced both the tank selector switch on the dash and the selector valve next to the passenger side tank. also i have took off the ground wires for the sending units in each tank and clean the crap out of them and still no luck also i have chased wires and found no bad wires what else can i check or try to do? Thanks

[Irish_Alley]

3 o'clock is too late to be reading imo, i dont like to do it at all but 3 o'clock i could be playing video games or sleeping. but anyway back to your GAUGE issue have you tested the gauge? since its the same no mater what tank your on i would think its the gauge problem

For Truck Years:  1967 - 1990
TEST PROCEDURE - SENDING UNITS

The subsequent charts provide precise sender resistance values for three specific gauge readings (Low, Medium, and High), hence, can be used to estimate sender resistance when actual physical parameters are known (e.g., engine temperature that is verified with a thermometer, actual fuel tank level, engine oil pressure that is verified with a manual gauge, etc).  Therefore, a sending unit’s resistance can be measured and “subjectively” compared to its interpolated value between ‘Low,’ ‘Medium’ and ‘High,’ based on the charts and the observable/verifiable physical conditions that actually exist on the vehicle.

The Fuel Gauge Needle Should Point to:
Left Line (Empty) when sender resistance = ~1 Ω
Middle Line (Half) when sender resistance = 44 Ω
Right Line (Full) when sender resistance = 88 Ω

but read up on this post
http://forum.73-87chevytrucks.com/smforum/index.php/topic,25339.msg211241.html#msg211241

[dustin1123]

thank you i will give it a try

[sphinx]

Look at this post http://forum.73-87chevytrucks.com/smforum/index.php/topic,25150.15.htmlIt will explain the way the fuel gauge works.  It might shed some light on where the problem is.  You don't have to build the LED gauge in the post it was just my plans to relocate the gauge.