IowaTom Posted April 30, 2022 Share Posted April 30, 2022 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. Link to comment Share on other sites More sharing options...
Gary Lewis Posted May 1, 2022 Share Posted May 1, 2022 Bummer! That rear gas tank is not the easiest to get to, for sure. Hope you get it replaced easily. Link to comment Share on other sites More sharing options...
BigBrother-84 Posted May 1, 2022 Share Posted May 1, 2022 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? Link to comment Share on other sites More sharing options...
FuzzFace2 Posted May 2, 2022 Share Posted May 2, 2022 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 ---- Link to comment Share on other sites More sharing options...
IowaTom Posted May 2, 2022 Author Share Posted May 2, 2022 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. Link to comment Share on other sites More sharing options...
mat in tn Posted May 4, 2022 Share Posted May 4, 2022 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. Link to comment Share on other sites More sharing options...
IowaTom Posted May 4, 2022 Author Share Posted May 4, 2022 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? Link to comment Share on other sites More sharing options...
mat in tn Posted May 5, 2022 Share Posted May 5, 2022 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" Link to comment Share on other sites More sharing options...
ratdude747 Posted May 5, 2022 Share Posted May 5, 2022 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? 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. Link to comment Share on other sites More sharing options...
Bruce moose4x4 Posted May 6, 2022 Share Posted May 6, 2022 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/ Link to comment Share on other sites More sharing options...
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