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Ford F250 fuel gauge issue

Discussion in 'Ford Trucks' started by cjc810, Feb 8, 2006.

  1. cjc810

    cjc810 Member
    from RI
    Messages: 69

    1988 Ford f250 gas gauge are pegged past full. Any fix suggestions or cause
     
  2. exmark1

    exmark1 PlowSite.com Addict
    Messages: 1,321

    I have owned a few of that era Ford trucks most all of them had some issues with one or more of the gauges! However one of them had the same problem you are describing and we just replaced the dash cluster in the truck and it worked fine up until I sold the truck!
     
  3. LINY Rob

    LINY Rob Senior Member
    Messages: 478

    I had that happen to my truck and had to change just the sender,

    once I did drop the tank I found the wire had fallen off the sender which you could only get to inside the tank, its submerged in gas.

    Figured the tank was down why not just put the new one in, better then putting a whole new pump with sender in like I originally thought I was going to have to.

    Now I wish that thing was still stuck on FULL
     
  4. cjc810

    cjc810 Member
    from RI
    Messages: 69

    Thanks for the suggestions.
     
  5. All_Clear

    All_Clear Senior Member
    Messages: 206

    I asked this a few months ago...

    Still havent got around to messing with it, but here's the best place to start your search since its common on these trucks....

    "OK, I have a problem with my gas gauge.

    This problem occurs regardless of which tank I am using, front or rear.

    When the fuel level in the tank I am using drops below about 1/4 tank, the gauge works ok. If I have more than 1/4 tank of fuel, it reads more than full. It pegs all the way over on the full side.

    Since it does this with both tanks, I thought it might be a problem with the gauge itself. Does that sound right? Or have both of my sending units failed in the exact same way?

    Any info would be greatly appreciated.


    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~


    It could be either.

    Ford uses 75 ohm fuel senders. So a full tank would be 70-75 ohms, empty would be 0-2 ohms.

    Now there are two problems with this.

    First, many aftermarket replacement senders use the same element, in different housings, thus saving manufacturing costs. Many of them use a 90 ohm element. So if your tank's have aftermarket senders, "full" will be "way past" the full mark.

    Also, because the more resistance there is, the higher on the scale the needle goes, the aging of the wires, poor grounds and so forth, add to the resistance. The fuel sender is grounded at the tank - so the stuff between that ground, and the ground on the firewall for the cluster, is a lot of potentially rusty stuff. The tank hole plate it mounts to, the tank itself, the tank straps, the frame, and the body bolts/ground strap under the hood.

    It's not uncommon for the fuel gauges to drift as the vehicle ages. To test this, run one of your tanks to "E", essentially empty, but not empty enough to stall the engine and plug the fuel filter. Then disconnect the battery, pull the cluster, and measure the resistance between a good ground on the firewall, and the wire in the connector that's for the fuel gauge. Flip the tank switch to each tank, one should have a very small resistance depending how empty the tank is, and the other should be 70-75 ohms if it's completely full.

    If you do have "correct" readings on your ohm meter (testing at the cluster connector), then it's the gauge itself (unlikely).

    If you have incorrect readings at the cluster connector, you can drop one of the tanks and measure at the fuel tank itself. If it's correct there, then you know it's ground related. If it's incorrect at the tank, then you know it's the sender itself.

    This is why garages will charge some money for this... measuring it at the tank is difficult because most people have hands that don't fit between the bottom of the bed and the top of the tanks to disconnect and reconnect the connector. I was able to do this on my side tank, but not the rear tank. My hands are "medium" I guess !?

    I had the bed of my truck off for part of the summer doing body work so I decided "screw it" and replaced both pumps and senders, so I don't have to think about failure in either tank for years to come. I hate spending money that I don't need to, but I hate taking out gas tanks even more."

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    My truck does the exact same thing... right now i'm living with it. once it shows a 1/4 i switch tanks, once that one hits a 1/4 i top them both off....

    All_Clear