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Flyfasteddie's avatar
Flyfasteddie
Explorer
Jan 31, 2021

Drained fuel tank, now fuel sender is inop?

I have a Ford E350 based Tioga motorhome with a 460 EFI.

3 months ago I drained the fuel tank because the rig had sat for a year and it looked like it was going to sit another 6 months. It was a fairly simple matter to disconnect the fuel filler inlet hose and snake a rubber siphon tube into the tank and drain the fuel.

A few weeks after that we were able to take the rig out and now the fuel sender isn't working. When the ignition is on, it registers two needle widths below E which is normally about 3-5 gallons usable. I put 20 gallons in it and it didn't raise at all (this would have registered just under 3/4 tank)

With ignition off, the needle drops considerably lower.

I thought maybe the float arm was stuck (but it only sat empty for 2-3 weeks) but we traveled over a fairly rough dirt road for 10 miles or so and I would think it would have "unstuck" it.

I also verified that the sender is getting power, because disconnecting the sender wire connector causes the gas gauge to drop all the way down to the same position as when the ignition is off. It definitely worked normally just before I drained the tank.

Any ideas? I really don't want to drop the tank, but if the sender is shot I'll have to. I just don't understand why draining the tank (which would have had 2-3 gallons still in it) would cause the sender to stop working.
  • JaxDad's avatar
    JaxDad
    Explorer III
    Jan 31, 2021
    There’s a couple of common potential issues that will cause this, the gauge works on resistance to ground, so any bad connection, corrosion, pinched wires, etc, will do that. So will a bad float that disintegrated or fell off the arm when you drained the tank. A bad resistor will do it too.

    How corroded is the underside? Dropping the tank and pulling out the pump & sender is the direct approach.
  • BFL13's avatar
    BFL13
    Explorer II
    Jan 31, 2021
    Had a stuck float in our 2007 Montana van that was cured (or it seemed to cure it by co-incidence, who knows?) with Sea Foam dumped in the gas tank.
  • Lynnmor's avatar
    Lynnmor
    Explorer
    Jan 31, 2021
    Sounds like your siphon hose whacked the wiring or sending unit.
  • ernie1's avatar
    ernie1
    Explorer
    Feb 01, 2021
    I had a similar problem with a previous MH that I had.It was a 1989 Falcon on a Ford E350 with a 460 engine. On a trip in Canada I had to take a ferry to my destination and loaded the MH onboard. This was shortly after I purposely filled both tanks with gas. When we got to. our destination, I got back into the rv and found one of the gas tanks reading empty. Thinking someone siphoned the gas out of that tank, I went to a filling station and tried to put more gas in but could only do about a gallon. So, weeks later, after I got back home, I dropped the tank and pulled out the sending unit and found that the brass float had developed a hole and was allowing gas inside to a point where it was no longer floating! The float was replaceable and I was shocked that the Ford dealer had one and it was only about $10. Worked perfectly afterward.
  • ksg5000's avatar
    ksg5000
    Explorer
    Feb 01, 2021
    If you have to drop the tank you might consider replacing the fuel pump which is 30 yrs old.
  • dougrainer's avatar
    dougrainer
    Nomad
    Feb 01, 2021
    I thought maybe the float arm was stuck (but it only sat empty for 2-3 weeks) but we traveled over a fairly rough dirt road for 10 miles or so and I would think it would have "unstuck" it.

    Odds are that 3 weeks caused corrosion on the fuel sending unit. AS it was totally exposed. You always leave the fuel tank FULL when not using or storing a Vehicle. Doug
  • Flyfasteddie's avatar
    Flyfasteddie
    Explorer
    Feb 02, 2021
    Thanks for all the replies. I have tried banging on the bottom of the tank, I'll see if I can get something in the gap to physically "persuade" the sender mounting plate.

    The Seafoam is a great idea, I haven't tried that yet.

    I may just run it this way for awhile, I've had it long enough that the fuel burn is very predictable and 90% of the time I'm towing ATV's and an extra 15 gallons of fuel. Maybe it will unstick, or I'll just get tired enough of it to drop the tank.

    I'm always leery of doing any kind of elective surgery on a 30 year old vehicle because something else always seems to break during the process.
  • klutchdust's avatar
    klutchdust
    Explorer II
    Feb 02, 2021
    I had issues with my Cambria not allowing fuel to be put into the tank. One hard stop in a safe parking lot cured that problem. The fuel swished around and cured it, could not figure out what caused it.

    What about inserting that hose again and adding some compressed air to agitate the fuel and possibly loosen the float IF it were stuck. Low pressure of course. My guess is the siphon hose was the culprit.

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