Hi everyone. I've read every post on fuel gauges and sending units before writing this. My old sending unit (original ford) when tank is full would only read 5/8's full, via the dash gauge. I just replaced it with a new one (aftermarket) and same thing. I tested by letting the wire hang and it still goes to 5/8's full. So assuming all the wiring is okay and the ground is good which it is, could it be the dash gauge. Is there a way to test the gauge like getting a correct resistance reading. The sending unit is showing a change in resistance as I raise and lower it which is why I think it's the dash gauge. One thing I don't understand is how a dash gauge can partially work, wouldn't it be broken completely or work properly ?????? Thanks.

 

22.5 ohms will give you empty and 145 ohms will be full on the gauge.

 

Thanks, that is what my new sending unit is reading, well very close to. Just filled up the truck to the max and the gauge won't go past 5/8's full. So I guess it's the dash gauge but I would have thought it would either work or not, but partially working is wierd.