Fuel Gage is inaccurate

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christopher.brandon

christopher.brandon

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Hello All,

A while back my Fuel Guage on my 74 Valiant would always show Empty. I replaced the Sending Unit and now, when I fill her up, the guage will show full. Unfortunately it will go back down to Empty after a few days of driving. Anyone have any insight onto what the problem could be?

Any information would be greatly appreciated!
 
Poor mpg ?
Have you noticed a similar wrong report from the temp gauge ? If not you may only need to tighten the gauge mounting. Those stamped tin nuts also serve a electrical contacts. Dont over tighten them. I use a 1/4 drive disc ratchet between 3 fingers. You'll need a deep socket too. Shallow is often too shallow.
 
I would check all the usual suspects.

Ground strap/jumper at the sending unit.
Connector on the sending unit.
Voltage limiter for the gauges.
As mentioned, the tin nuts on the gauge, I switched mine to regular nuts and cleaned the studs and circuit board real well.

When I did mine I just started at the 12 volt power-in to the cluster and worked my way back until I found the problem.

Make sure you have 12v to the power-in on the cluster with the key in Run.
Make sure you have 5v output from the voltage limiter with the key in Run. (this is where doing the solid state conversion is good because your stock voltage limiter can be intermittent).
Check continuity between the gauge output and the connector on the sending unit using an ohm meter or circuit tester.

There is some good info here about the gauge voltage limiter...

http://www.allpar.com/history/mopar/electrical2.html

http://www.moparfins.com/Repairs/Fuel_Gauge_Repair/Fuel_Gauge_Repair.htm
 
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