so i just bought the truck, the guy told me he thinks the float was stuck, i youtubed and took the bed off and got the pump out and sending unit wasnt stuck, im not too sure how to do a diagnostic on this issue but any help would be appreciated. its a 4cy 5spd. thank you.

 

Welcome to the forum


Ford uses a Yellow/white stripe wire from fuel tank sender to the instrument cluster fuel gauge

The sender is grounded at the fuel tank by the Black/orange stripe wire

Fuel gauge reads Empty when yellow wire is below 20 ohms
Fuel gauge read Full when yellow wire is above 150 ohms

So for gauge to show Full all the time then OHMS would have to be above 150, quite a bit above if it goes past Full.

A disconnected yellow wire(or Black/orange ground wire) will be infinite OHMS, very very high, above Full
A shorted yellow wire would be 0 OHMS so below Empty

A stuck float would show Empty usually, but could stick high but never above Full, so don't trust what seller said, lol, which you already found out.
Sender could have broken wire inside, that would cause above Full

If you still have the bed off, then get a Volt meter and test the yellow wire for Pulsed 5volts Key on, engine off
Also test black/orange wire for good ground, ohm meter at 200 ohm setting, should show 0 ohm
Test the sender wires(connector) with ohm meter, should read between 16-158 ohms depending on how much fuel is in the tank

Then theres the Anti-slosh module, google: Ford Ranger anti-slosh module

Usually these cause Empty gauge all the time but...............they can fail "open" so past Full

 

 

ok so it was the sending unit, i checked all cables everything was connected correctly, i then tested the wires you specified the white and yellow and it had voltage next i measured resistance and it was too high for the 200 reading, i then measure at the pump and same it was super high, i bought a new fuel pump and sending unit for about $99 free shipping and easy does it now my baby reads the fuel!!! thank you guys for the info and the help!!!

 

Good work

Thanks for the update