I have been doing a lot of research as to why our gauge is stuck at full. I have seen several possible culprits.
It started when it showed 1/8th and ended up being out of fuel. After putting fuel in, it went past full and has stayed there.
I have disconnected the battery and it will not go down. Is there an instrument cluster test for analog versions? I really don't want to replace the sending unit.
I thought that with no power, it would go back to E.
I have put in a bottle of Techron, as an additive should never hurt.

Thanks in advance for any and all help.

 

Welcome to the forum

1989 and up Rangers/Fords use these OHMs for fuel level
16 ohms = EMPTY
160 ohms = FULL

0 ohms = direct connection, short to ground, below empty
over 160 ohms means no connection, above full

Dash fuel gauge/slosh module--------------(yellow/white wire)-------------------------------sender/float-------(black/orange wire)----------------ground

So you have a disconnection somewhere between gauge and ground on the sending unit
Best place to start is at the instrument cluster, it will need to come out

Once cluster is out you will have access to the yellow/white wire, pin 12 on center connector and access to Slosh module(common failure)
Hook up OHM Meter to yellow wire and cab Ground
Should see between 16 and 160 ohms, depending on how much gas is in the tank
Rock the truck and watch OHMs, should go up and down as gas sloshes around and moves float up and down
If that happens then wiring and sender are OK

If OHMS are above 160 then you will need to unbolt the bed and slide it back enough to access the wires on the top of the tank, and test OHMs there

Most likely its a slosh module issue, bad sender or float usually shows empty
Looking at the back of the cluster in the upper right is the slosh module, pull it out
Picture of the back of a cluster here: https://www.therangerstation.com/Mag...gauge/gr-8.JPG
You can see the Slosh module, green circuit board

You can try cleaning the contacts on the module and on the cluster, then plug it back in hook up the 3 connectors and turn the key on to see if gauge shows correct level in the tank
You can Google: ford ranger slosh module
There are ways to by-pass it with jumper wires

1996-2003 Rangers and most Fords, used the same slosh modules in the cluster, so hit wrecking yards to find a match

 

Is the fuel gauge supposed to drop back to E when there isn’t power? My apologies, but I am a bit confused.

I was going to pull the bed and replace the sending unit assembly. Looks to be easier that dropping the tank. I just have to remove the liner first.

Is it possible to check the resistance coming from the sending unit connection?

Thanks again for your input.

 

No, fuel gauge will usually go to 1/8 to 1/4 level with key off, but never down to empty or below, it would usually stay above full if sender is disconnected

You can Google: Ford gas gauge always on full

And read some of the posts and responses, there will be MANY, lol
Its all just a "best guess" until you do some testing




Not that it matters, 2004 and up with digital dash does go to empty with key off I believe