I'm having an issue with my 94 extended cab, the gas gauge doesn't read at all when the truck is on (it stays pegged on E), but after it's been sitting while off for a while, the gauge reads normally. it's an aftermarket pump and sending unit, and today I verified that everything was in proper working order. The float isn't sinking, and moves as it should, but it doesn't read anything at all when the truck has power. Thanks.

 

The gas gauge uses a spring inside so when power is off it will go up a bit, with key on and there is a problem(or empty tank) it will drop to E again

On the back of the instrument cluster is the Anti-Slosh Module, its a separate circuit board, unplugs from the cluster
Not a common, but a known failure point for gas gauge "always on Empty"

Google: Ford Ranger anti-slosh module

You can by-pass the module with jumper wires, have to pull out the cluster to get to it
Or replace it, 1989-1994 used same model, I think most Fords in those years used the same module so wrecking yard might be a good place to get a replacement

When you have the cluster out, TEST the yellow/white stripe wire on the connector, thats the wire from the gas tank sender
Connector "B" pin 5, but its the only yellow/white wire
Use an OHM Meter
Sender uses
16 OHMs Empty,
158 OHMs Full, F
So you will see something in between
And if you rock the truck, slosh the gas in the tank, you should see OHMs going up and down as Float goes up and down, if so sender is OK

If you see 0 OHMs then yellow/white wire has a short to Ground, 0 OHMs is below 16 so below E on the gauge

Anytime you have the Cluster out replace all 6 Back light bulbs, they are cheap

 

Thank you so much, I did the bulbs about 2 years ago actually haha, I've had that cluster out more times than I can count. thank you so much though