Fuel gauge issue

[TexCaliBII]

Guys,
Got a head scracther here. I put the 4.0/5 speed/dash and entire chassis harness from a 93 Explorer in to my 88 BII and it runs and drives great but the fuel gauge didn't work, always read empty. Discovered the BII and Ex sending units use different ohms ranges. So I ordered up a sending unit for a 93 Ex and installed it. Wasn't too worried as I had already installed a new pump/sending unit in the BII before the mods so everything came out easy, this time. However, now the fuel gauge drives to over the full mark????? I double checked my wiring, ground is good and the signal wire is good all the way to the gauge cluster. I also swapped out several anti-slosh modules and another fuel gauge. I also cleaned the connector between the tank and chassis, just in case. Still not working. I pulled the tank back out and pulled the sending unit to verify all was good, I know I should have checked BEFORE putting the tank back in..... The readings were right where they should be though, 22 empty and 145 when the float was set to the full level. SO how can the wiring, grounds, and ohms be correct and the gauge reading backwards????

 

[gribly]

Wait, it reads empty when full and reads full when empty?

 

[TexCaliBII]

No,
I just put about 5 gallons back in the tank and the gauge still drives to the full side. After more research, I'm thinking I might have an issue with the new sender grounding out and driving the gauge to the full side. Although I already checked for continuity and ground and all are correct. Also the guage wasn't driving anywhere with the BII sending unit in the tank with the same wiring harness....

 

[gribly]

Oh. I guess I can't really help you on that one...

 

[TexCaliBII]

Okay,
I'm an idiot. Turns out the connector on the truck side had a rim on the barrle that prevented the pins from connecting. Removed it with an excto blade and they went together. I now have a correctly reading fule gauge. Still scratching my head on how it read good at the gauge cluster if the pins were not touching in the connector. Oh well, it's working now.