Fuel gauge reads backwards
 

I've had this nagging problem since it put the truck back on the road. My original tank rusted out so I replaced the tank, pickup w/pump and sending unit.

I read on a past post to read the resistance of the sending unit so I dropped the tank last weekend and the resistance was 15 ohms almost empty.

Any thoughts?

I have read that the newer trucks read backwards compared to the 1980-1986 trucks.

What is the Ford engineering number on the sending unit?

Also what year is your truck?

It sounds like you mis-matched the sending unit with the wrong year range.

You got the right idea, but not quite right.

1980-1986: The Fuel gauge reads full with the least resistance.
1987-up: The fuel gauge reads full with the most resistance..

The tank assembly came from MTS.

And to add, I bought a tach gauge assembly from a member off the boards.

I have a 85 F150 FI302 that has a single in the tank pump.

When I dropped the tank last weekend it was almost empty, but the gauge read almost full and was 15 ohms of resistance.

Gauges don't interchange between models of trucks do they?

I would say your sending unit is the culprit, and they gave you the wrong one for your application.

1980-1986 sending units should read between 80-10 ohms resistance. 10 Ohms being Full, 80 ohms being empty.

1987-Up sending units read the exact opposite. 165 ohms full, 10 ohms empty.

No the later 1987-up gauges are different.

Great info! Then my next step will be to call MTS.