Sending Unit

I'm wondering if it is at all possible to clean the electrical contacts of the sending unit because of the effect of what you guys call "olephins". I
have a sending unit on my 1983 F-150 that when if I hook it up outside of the tank and move the float up and down, my gauge will work correctly. However, after a day of working perfectly inside the tank, the gauge all of a sudden stopped working and now I am wondering if it can be cleaned to a state that which it may function again. As far as the unit itself, it is in good condition, no rust or broken contacts, etc. The two male connectors on top of the unit that the round rubber female connector plugs into is in good shape, as is the other connector. This afternoon, I also tried dropping the tank enough to pull off the connector and wire up a seperate ground off the frame of the truck to the sending unit. This did not make any difference, and I have already replaced both wires running along the frame up to the gauge, so I know there is no problem there.
Anyway, can it be cleaned, and if so, what should I use to do it?
Thanks for any help Sharky
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If your gas is causing this, I would change suppliers/brands pronto!
I think perhaps you didnt look / test close enough when you had it out.
IIRC, the contact arm is grounded, and the resistance wire is connected directly to the sender connector. If the ground is supplied to the arm through the pivot that would be my suspect point.
Solution: very flexible wire, to the arm itself.

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Backyard, thanks for the reply. I'm not sure if the gas is causing this or not, but the arm/float looked fairly clean on the sending unit and all of the electrical contacts I could see looked clean and unbroken. The only thing I did not look at was the contact point inside the little metal box that the float arm moves up and down on. The ground on the sending unit stops on the other side of the pin contact, so I would have to assume that it grounds through the fuel tank itself, through the round base plate. Just to make sure it is getting a proper ground, I have already run a seperate wire from the frame to the ground pin on the connector, so the ground should not be an issue now.
I may try pulling the tank down and removing the sending unit later on this afternoon and then clean it with sandpaper/SOS pad very carefully. You can take that metal box apart where the float arm moves on the coiled wire, so I may pull the cover off and see whats in there. I took the old one off the sending unit I just removed and the coiled wire inside was still in good shape. There was a bit of dirt in there, but nothing serious, so I doubt this sending unit would be much worse as it was in twice the condition the old one was.
It just strikes me as odd that when I had the sending unit out of the tank and hooked up, it was working fine. And I did not clip a ground wire to it, I just hooked the connector up and moved the float in my hand. I really don't think it's the fuel causing this because I've been using the same brand on two other vehicles for the last 4 years and the fuel gauges in each work fine.
Sharky

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UPDATE: Well, it obviously isn't the gas causing my fuel gauge to stop working, or any of the wiring for that matter. Went out this afternoon to replace the inner/outer tie rod and when I took it for a short spin to see if it was still in alignment, my gauge "magically" started working again. Now it's reading where it should be, 3/4 and I haven't touched anything to do with the gauge or sending unit since I replaced the old one last week.
I guess this is to be expected from a 23 year old truck, LOL. At least everything else works OK on the truck.
Sharky
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I had a similar problem on my 82 f100. the gauge registered empty, even though gas was there. mechanic said it was float problem, said it was common.
so i dropped tank and pulled sending unit. the float was ok. I reinstalled tank and it started to work again. now, it works intermittently. i haven't worried too much about it since i have two tanks and don't drive the truck very much. i assume that the contacts need cleaning, which i will do sometime (when it gets cooler).
if you drop the tank, do not destroy the larger rubber hose that gas flows into (when you're pumping gas). mine was difficult to remove so i was just going to cut it off. i decided to get a new one before i destroyed the old one. however, the inlet hose cannot be found, even from Ford. i was able to reuse the old one. you might be able to find a flex hose that would work.
UPDATE: Well, it obviously isn't the gas causing my fuel gauge to stop working, or any of the wiring for that matter. Went out this afternoon to replace the inner/outer tie rod and when I took it for a short spin to see if it was still in alignment, my gauge "magically" started working again. Now it's reading where it should be, 3/4 and I haven't touched anything to do with the gauge or sending unit since I replaced the old one last week.
I guess this is to be expected from a 23 year old truck, LOL. At least everything else works OK on the truck.
Sharky
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Stevie, thanks for the suggestions. Sometime soon, I probably will drop the tank again and pull the sending unit out. I had no problems with the filler tube, I just unclamped it at the gas cap end and it came straight down with the tank. Once it's out, I will clean the contacts, but I'm not sure what to use to clean it. I've found WD-40 only works for so long, so I will probably pick up some kind of electrical cleaner from Radio Shack.
It has been working intermittently, like you say yours does. Just depends on the day of the week I guess :-) . Anyway, I guess I'll just keep the full jug of gas on board for a little while longer. I'm glad that this isn't my daily driver, it only gets used for certain tasks.
Thanks for your help, Sharky
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