99 Ranger Fuel Gauge Problems

[Wolfman88]

I have a 99 Ranger I was rebuilding for myself until I found and bought a 91 4X4 STX so I'm going to give the 99 to a friend but I'm trying to figure out the fuel gauge. It reads past full no matter where the float is it does this with both the sending units I have also when it's unplugged but when I do the test of connecting the ground to the signal wire Y/W it stays reading past full until I turn the key off and back on then it drops to E. The senders seem to be working the ohm reading changes depending on float position. When I did the ground signal wire test I did it at the fuel pump connector instead of behind the cluster.
Any ideas?

Edit to add the truck has been sitting in my shop with a empty tank for over a decade but the fuel gauge worked when I took it off the road fuel pump works with some gas it fired right up.

 

[franklin2]

When you do your ground test at the connector(with the key in run) try different grounding spots. First place to try is in the connector itself, it should have a ground wire in it. If you find it passes the grounding test when grounded directly to the battery, you might have a ground wire problem somewhere.

 

[Wolfman88]

When I have the sender disconnected and ground the signal wire when I turn on the key the gauge drops to E. With the sender connected or disconnected without grounding the signal wire turn on the key gauge goes past full. I checked the ground wire against the frame for continuity has good ground did the same for ground to body of the sender good there. Signal wire has continuity from just behind the main truck harness connector to sending unit when disconnected from sender signal wire gets its 12V. Ohms on sender itself range from around 15 to 150.

This is why it has me confused everything seems right.

 

[franklin2]

Only thing left is the connector itself not making contact when plugged in.

 

[Wolfman88]

Connector is making contact I poked a small hole in the wire on the trucks wiring harness and checked where the attaches to the sender and got continuity but I figured can't make it more broke than it already is (famous last words) and took the sender itself off and apart and looks like the arm that should be grounded (has kinda pressure piece that makes contact with the metal back plate that the ground wire bolts to) wasn't making contact so it wasn't being grounded. I'll post a pic in case anyone else has this problem just clean the tabs and backplate and bend the two arms out a bit so it gets good a ground careful the plastic can be brittle.

I haven't got everything back together yet but will let everyone know if that was the problem.

 

[Wolfman88]

Well, that was the problem cleaned the contact points bent the tabs out a bit and now have a working fuel gauge.

 

[franklin2]

...........but I figured can't make it more broke than it already is..........

I like your logic there.