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I need to replace the back tank fuel sending unit. Which is "easier"? Dropping the fuel tank or taking the bed off? Thinking if I take the bed off I can change both units and would probably replace all the fuel lines but I am a little concerned on the hornets nest I might be opening up trying to get the bed off of 1986 truck. Any advice from this wise group of experienced minds?
I need to replace the back tank fuel sending unit. Which is "easier"? Dropping the fuel tank or taking the bed off? Thinking if I take the bed off I can change both units and would probably replace all the fuel lines but I am a little concerned on the hornets nest I might be opening up trying to get the bed off of 1986 truck. Any advice from this wise group of experienced minds?
not really a bad job. Tailight wires, fuel fill hoses, and 8 bolts. Get a few people to help lift it. Hardest part is putting tension on the bolts from up top while loostening it from the bottom. LMC sells new bolts if you need to replace them.
Last edited by Denzil B; Dec 15, 2025 at 11:29 AM.
Start spraying the bed bolts now.
I did that a few weeks before I had to remove the bed from my parts truck and mine came right off.
You can see the hoist hits the side of the bed but I did not care as the other side was crushed and I was cutting the sides off as I was going to use the floor for my truck.
Dave ----
Getting the bed bolts loose is a miserable job on a rust belt truck. I will drop the tank any day. All you need is a floor jack and a piece of wood. It does help if you can siphon some the fuel out of the tank.
When you know you will drop the tank and dont have a 2nd tank to use get a 2 gallon gas can and keep it full in the bed.
Run the truck around town till it runs out, dump in the 2 gallons and drive it back home and drop the tank.
I was lucky 1 of my senders stopped working so I ran that tank till it ran out of gas and switched to the other tank.
The hard part was it was the rear tank and I have a frame mounted hitch and a flare side never had a rear tank so dealing with the filler hose was a real PITA.
I was able to drop it just enough to get the sender out and found the float full of gas. I used one of the old sender floats on the new sender and has been good for years now.
Good luck
Dave ----
I had a full tank when I discovered it was leaking. That would have been a lot of driving around to empty it. I had jerry cans and used a cheap hand pump from Harbor Freight which pumped out all the fuel except maybe a tablespoons worth. Definitely empty your tank before dropping one. Since you have two tanks to work on lifting the bed has to be considered. You can then do some work on cleaning up and painting your frame and bed bottom. If needed.
You style side bed guys have it made as the bed has lips to hook to and the bed is 1 piece.
Us flare side guys dont have a lip to hook to, it is a rolled edge to the outside, and the sides bolt to the outer wood planks so it comes apart in parts.
If I had a way to lift mine I could as my sides are bolted to a style side ribbed bed floor so I could just undo the bed bolts too.
That gets me thinking
Flare side bed guys I wonder if you could lift out the center planks or panel if plywood used later years, to get to the sender
Dave ----
Was able to get 5 of 6 bolts out fairly easily, It would be nice if you could reach all six with an impact wrench. Ended up grinding off the head of the last one (which wasn't a lot of fun). Replace both sending units all new fuel lines. Hopefully good for at least another 10 years! All back together and everything works as it should. Thanks again for the comments!
No just water that hadn't dried yet..... I didn't realize that the tank was almost full (fuel gauge was reading E ) when pulled it up, I dumped about a gallon of gas on the floor my garage. Figured after wiping most of it up, it would better to wash the floor than throw a match down.
Water? Well I would have scoogied, scrubbed, washed, dried, painted, cured and then a generous brush on of Fluid-Film black! But heck you might have needed a rig right away. In that case skip right to a coat of Fluid-Film black and throw the bed back on.
I think the water was to wash away the gas that came out when he removed the sender as the tank was full unbeknown as the gauge was reading "E"
I can see pulling the bed, replace the senders and put the bed back on just to "get r done".
Dave ----
) when pulled it up, I dumped about a gallon of gas on the floor my garage. Figured after wiping most of it up, it would better to wash the floor than throw a match down.
