Dead fuel sender

When I replaced my (rear) gas tank on the '85 F150, naturally I also bought a sender on Ebay.  The other day, after firing her up and letting the engine warm a little, I witnessed the gauge needle slowly fall to empty.  Waaah!  I KNOW I'm not using gas that quickly.
Now I wish I'd bought the sender from O'Really's so I could take it back...and the replacement process is not going to be fun.  Last time under there, I dropped the gas tank on my head trying to work it into place.

Bummer!  That rear gas tank is not the easiest to get to, for sure.  Hope you get it replaced easily.

IowaTom wrote

I KNOW I'm not using gas that quickly.

Our beloved drink a lot  but not that much!
Good luck with that issue.  If your lucky, this could be a simple wiring problem?

As part of the rebuild I replaced both senders on my truck.
Shortly after being on the road the rear tank sender also stopped working
I run the rear tank dry and then sucked it up and dropped the tank.
Now I did not want OR need to drop it all the way.
I was able to drop it down enough to sneak the sender out.

Once out I found the float took on fuel and sunk to the bottom.
I want to say based on how it was dropping either the wire came off or the float is bad.
My fix was to use the float from the old sender. Yes I still have them and its over 2 years now.
Dave ----

Thanks, Guys!

In the case of a bad float, it could be mine has taken in fuel.  When I took the old one out of the tank I eventually cut up and recycled, the float was gone.  It wasn't in the tank anywhere so I assumed Ford used cork back then and it just crumbled over time.

Think I'll also run this near dry and drop the tank again.  At least it's clean there now.

unfortunately, we hear of this a lot, and I dealt with it repeatedly on the last truck I built. from bad grounds to miss adjusted float arms. if one can sort all of the quirks out while the bed is still in the rack that would be wonderful! if need be, a simple circuit for an ohm's test would suffice if the rest of the harness is not ready. that won't fix a saturated float though. buoyancy is a must.

Yeah, Mat, I was looking at the 8' bed and wondering if I could somehow slide it off.  Naaah!  To heavy and I'm bound to bend sheet metal doing it.  I'll just driver her around for a while and siphon out the rest of the gas before going through the process again.
Can anyone recommend a good, reliable sending unit that's worked for a long time?

original! everything else is a "make do"

My spectra one hasn't "failed" in the last few years I've had it. But, as I've mentioned elsewhere, my gauge is highly non-linear and as a result I've run out of gas a couple times. the needle falls fast when full but as the tank empties it slows down (1/4 gauge is maybe 1/2 tank or so). When on the E mark, sometimes it'll have 3/8 a tank or more. But if you don't get gas as soon as it starts dropping under, you're likely to run out in an embarrassing location (work lot during shift change and a Wendy's drive thru in my case). Given that I swapped fuel gauges and had no change, I'm fairly confident in saying it's an issue with the sending unit/ stock design.

One thing to note is the spectra units are a newer style design using a carbon track type potentiometer instead of a wirewound potentiometer like the original and many knockoffs use. My stock one failed due to the wire in the potentiometer burning out; a chinese ebay knockoff I tried was dead out of the box.

This place can rebuild senders to new status.

https://tristarrradiator.com/

Bruce moose4x4 wrote

This place can rebuild senders to new status.

https://tristarrradiator.com/

 
Not at the moment:

"Special Notice, Please Read. As of March 1st, 2022
Due to an excessive amount of backlogged sending units to be rebuilt we are not accepting anymore units as of this time; our current backlog of 16 weeks being the reason for this decision. We are sorry for any inconvience this may cause."

I bought another (cheap) one and it didn't work, right out of the box.
Mat's right, time to get one from Ford.

I had the pleasure of dropping a 38 gal super tank this morning because the sender and pump failed. the sender was one of the sloppiest moving that I have seen. having another used but original on the shelf I tested it and swapped it onto the sending unit and tested it multiple times. the circuit looked great  so I used it. nothing fits like oem! not even "same as oem". its ford or its not! but we often are left with what we can acquire. I left the pump swap and reassembly for the junior as I had to return home