Fuel Level Sender Pegged

crash-harris

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Back with a new (to me) bricknose IDI. As I'm working through fixing or modifying a few things, one of the more minor things I really want to fix is the front tank always pegs the dash gauge.

Tanks are switching correctly every time. Rear tank reads fine, front tank always pegged. Rear tank level will flutter and not read correctly if switched from the front tank while driving.

I've crimped in a ground wire jumper where the ground for both fuel level senders tie into each other, with no change. I did try cleaning the contacts on the front sender with a brass brush, but this truck still has the factory muffler and is very much in the way (and weirds me out not being able to hear the exhaust). Contacts on front sender appear very clean. Contacts for the FSV appear clean as well and have dielectric grease packed in. Truck is in really good shape and all the wiring is looking good with no noticable pinches anywhere.

Any ideas what I should be looking for next? If I'm looking at replacing the sender on the hanger, that's not so hard, but won't happen until I get the stacks transferred from the crew cab, due to the muffler being such an obstacle. Both senders in the crew cab function perfectly (parts WILL be donated).
 
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chillman88

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I would think try unplugging the FSV with it on the front tanks, then jumper the sender wires at the plug and see if it's working. If not it would have to be the sender I would think.
 

Selahdoor

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3/4 of a tank of fuel, and several miles down a VERY bumpy road...
 

crash-harris

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I would think try unplugging the FSV with it on the front tanks, then jumper the sender wires at the plug and see if it's working. If not it would have to be the sender I would think.
I thought when the senders go, they short and read empty? I guess I can try jumpering at the FSV plug once I finish fighting with getting the big mirrors on.
 

chillman88

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I thought when the senders go, they short and read empty? I guess I can try jumpering at the FSV plug once I finish fighting with getting the big mirrors on.

I honestly don't remember. I had issues with mine, but that was a while ago.
 

frankenwrench

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My senders both died within a few months of each other. Both pegged over full when this happened. Many of time did I make the walk of shame a mile or so up the road with a 5 gallon fuel jug and return to dump it in the rear tank and get the trusty old 5\8 out of my door pocket and start cracking lines on the side of the road till she came back to life. Then hit the gas station again. And as soon as I got my rear sending unit, the fsv gave out for the 5th time that year. Got the 38 gallon tank and modified my sending unit to fit and slammed it in there and ripped the side tank out and bypassed the fsv with new fuel lines and was happy for a good while. Then Wes at Classic Diesel Designs came out with a kit to do just this but with the sump. If the fsv hadnt have kept failing each time I replaced it i would have kept it and had more fuel capacity. But im getting off topic here. Lol
 

crash-harris

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My senders both died within a few months of each other. Both pegged over full when this happened. Many of time did I make the walk of shame a mile or so up the road with a 5 gallon fuel jug and return to dump it in the rear tank and get the trusty old 5\8 out of my door pocket and start cracking lines on the side of the road till she came back to life. Then hit the gas station again. And as soon as I got my rear sending unit, the fsv gave out for the 5th time that year. Got the 38 gallon tank and modified my sending unit to fit and slammed it in there and ripped the side tank out and bypassed the fsv with new fuel lines and was happy for a good while. Then Wes at Classic Diesel Designs came out with a kit to do just this but with the sump. If the fsv hadnt have kept failing each time I replaced it i would have kept it and had more fuel capacity. But im getting off topic here. Lol
I have the 38 gallon tank in the crew cab, but a hole rusted in the sump and it's only a few years old! I could never quite get the float arm adjusted to read properly. I have gotten the chance to jumper it at the FSV harness (which works much better than the one in my CCLB), but I'll plan on that sender being one of the things that needs donated to this new truck.
 

crash-harris

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This is odd, but I've just dropped below 3/8 of a tank in the rear and filled it back up, now the gauge is pegged all the way for the rear tank too?

Does not having a connection send the gauge to max?
 

crash-harris

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I must have at least one bad and one intermittent connection. With any luck, they aren't between the pump hanger and sender!
 
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