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Fuel Tank Sending Unit

Discussion in 'Early CJ5 and CJ6 Tech' started by kenb, Sep 7, 2019.

  1. Sep 7, 2019
    kenb

    kenb Member

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    150
    Hello,
    I have a M38A1 with an original M38A1 fuel tank under the seat. It has been converted to 12v electrical. I have two different 12v fuel gauges for it. When connected, both gauges show full when the tank is full and 5/8 tank when the tank is empty.
    I would assume it's an original 24v sending unit and that's why the issue. However, all the catalogs show the original sending unit as having a 5 screw attachment for the M38A1. My tank has a 6 screw attachment. The top of the unit is 3.5" diameter.
    Can anyone confirm the diameter of the CJ5 6 screw sending unit?
    Thanks,
    Ken
     
  2. Sep 7, 2019
    timgr

    timgr Jeepin' Nerd Sponsor 2019 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    20,160
    Voltage should not matter to the sending unit. At least on the CJs, it's a variable resistor to ground. As long as the resistance range matches your gauge, it will read the correct level. Can't help you with the sender top plate diameter though... though I would have removed and measured the resistance long ago. The M38A1 manual should tell you its resistance range, and the CJ TSM definitely will.
     
  3. Sep 7, 2019
    kenb

    kenb Member

    Detroit
    Joined:
    Jan 22, 2019
    Messages:
    150
    I think it's roughly 0-74 ohms. I did check it with an ohm meter but failed to write it down. I'll recheck next opportunity I get.
     

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