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1994 LHS Fuel light Issue

Discussion in 'LH: Large Cars, 1993-2004' started by JerCrest01, Aug 15, 2018.

  1. JerCrest01

    JerCrest01 New Member

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    Hello,

    I am writing to see if one (or any) of the people here can help me diagnose an issue with my fuel light. This happens when I fill the tank when it gets to 3/4 tank the fuel light wants to come on, as well my fuel gauge goes dumb. Any help would be gladly appreciated.

    On another note: I need options for replacing O2 sensors both Upstream and Downstream.
     
  2. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    Fuel gauge issue usually means pump replacement to solve it.
    Best O2 sensors are Denso and NTK. Avoid Bosch like the plague.
     
    Doug D likes this.
  3. ImperialCrown

    ImperialCrown Moderator
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    Some fuel gauge sending/level units can be serviced separately from the pump. You should have a plate on your trunk floor to access the pump from the top without dropping the tank.
    Gasoline fumes and exposed liquid fuel is flammable. Use caution when servicing open fuel tanks.
     
  4. Gerry G

    Gerry G Well-Known Member

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    Run a bottle of Techron Fuel system cleaner in with the next fill-up. If there are any deposits on the level sensor this should clean them off. It may be necessary to run a second bottle through on the subsequent fill-up for extra cleaning.

    One upside is that the fuel pump is accessible through an access panel in the trunk. No need to drop the tank.
     
  5. Bob Lincoln

    Bob Lincoln "CHECK FAULT CODES"
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    If that doesn't work, the metal contacts for the rheostat are likely eaten away. I had a flaky gauge, and after 24 years, the contacts for the wiper were gone.
     
  6. ImperialCrown

    ImperialCrown Moderator
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    Google for: Mopar part # 5014025AA if it needs a level unit.
     
  7. AllanC

    AllanC Well-Known Member

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    The fuel level float assembly in the tank provides a variable resistance circuit. The circuit connects to the BCM (body control module). I am thinking that if there is a problem with a small portion of the resistance contacts on the assembly inside the tank, it is giving an out-of-range signal to the BCM for fuel level. The BCM notes this and is illuminating the low fuel lamp as a warning and freezes the fuel gauge pointer and does not allow it to move.

    Do you have a driveability / engine operational issue which makes you think you need to replace the oxygen sensors? Since this is a 1994 model and uses OBD I engine management a downstream oxygen sensor is not present.
     
  8. ImperialCrown

    ImperialCrown Moderator
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    The level unit is a resistance 'card' with a wiper contact. It is subject to wear and will 'open' in spots.
    O2 sensors do get tired. It would be best to confirm this with a scan tool before replacement. Do you have an O2 sensor fault code? Use OEM if replacing. Mopar used NGK or NTK or Denso. Avoid Bosch or 'Universal' sensors.
     

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