I've been searching the site and other places and I haven't come up with an answer to whats going on with the new fuel sending unit I put in the rear tank of my '89 F250 - No matter how much fuel I put in the tank it always reads half a tank, be the tank empty or full. This has caused a few situations where I've run out of gas.

I bet the sender I purchased is bad, but I was just wondering if there was any other possibilities for the constant half-tank reading. Anyone have any ideas?

 

ive got the same problem with my front tank always reads wayy past full, not sure if theres anything in there.

 

Way past fuul means too much resistance probably the thin metal on the plastic board wore off where the little metal finger sweeps in the sending unit. Much like an old slot car track with the trigger speed control. Does the fron tank read ? Mine stayed in one spot and it ended up being the gauge cluster.

 

Do you have dual yanks tbolt? Does front tank work?

 

Pull the sending unit plug off, it should go to full ground it and it should go to empty. I could have that backwards too.

 

I am not familiar with it. the tank closest to the end reads fine(not sure if that's considered rear or front), but when i switch to the other tank closer to driver it shoots past full.

 

this is exactly whats wrong with mine!

 

I would start at the selector valve plug and go back then. Resistance shouldnt be more than like 120ohms or so i think. Cant remember exactly what they are without having my fuel.sending unit book from parts store in front of me. I would bet that unit is bad. You should be able to swith to that tank unplug it and ground it and see if gauge goes both directions. Be sure to switch to that tank so your not chasing your tail. Dont ask why i would say that. Lol

 

I dropped my tank yesterday and my sending unit switch had fallen off of inside the tank and the yellow wire was broke off too! So i readjusted the copper tang so it made better connection then i re soldered the wire on an put it all back together and walla!! It works!!!

 

Sorry, I had no internet access over the weekend. Anyway, yes I have two tanks, the gague works fine for the front tank, but I replaced the rear fuel pump and the old sender went bad (always red full) so I put in a new sender and now I have this constant half-tank reading nonsense that Ive not run into in 15 years of turning wrenches.

Like I said I figure the sender is bad, its just chosen a new and improved way of being bad - I guess thats what you get from part store junk...I'd just always had good luck with Spectra Premium parts.