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84 sending unit replacement

Discussion in 'Tech Discussion' started by Kevin Dugan, Sep 27, 2018.

  1. Kevin Dugan

    Kevin Dugan Junior Member

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    I have an 84 C10 with a single tank on the driver's side. The sending unit is bad.
    What is the best way to replace it?
    TIA,
    Kevin
     
  2. 1973c10

    1973c10 Full Access Member

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    I think you have 2 options drop the tank to pull the sending unit
    or pull the bed to get to the top of the tank to pull the sending unit
     
  3. Gpaw44

    Gpaw44 Junior Member

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    I am looking at the same thing. I have done both and I am thinking it is easier to pull the bed. Everything is very visible with the bed off!
     
  4. Kevin Dugan

    Kevin Dugan Junior Member

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    Thank you.
     
  5. 1987 GMC Jimmy

    1987 GMC Jimmy Full Access Member

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    I’ll play devil’s advocate here and advocate for dropping the tanks. It’s worth it to clean it out and inspect for rust. If it has it, a good, old school radiator shop can rod it out. If it’s never been done, expect the tank to be filthy. If the truck sat for a prolonged period of time throughout its life, expect surface rust. Ethanol attracts ambient moisture which leads to that rust over time.
     
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  6. Kevin Dugan

    Kevin Dugan Junior Member

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    So how do I know what size tank it has before I drop it?
     
  7. 1987 GMC Jimmy

    1987 GMC Jimmy Full Access Member

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    If it’s a SWB, it’s got a 16 gal. If it’s an LWB, it came with a 20, which is what it’ll have unless someone stuck a 16 there for whatever reason.
     
  8. Kevin Dugan

    Kevin Dugan Junior Member

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    Thank you.
     
  9. donnieray

    donnieray Talks to dogs and trucks. Supporting Member

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    On my 84k long bed I was able to remove the bed bolts and jack the front of the bed up enough to do the job. In my case the tank was clean inside but I chose to replace all the rubber lines. It would just be crazy not to. Don't forget to unbolt the filler hose from the bed.
     
  10. bucket

    bucket Super Moderator Staff Member

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    If it's a short bed, you have to drop the tank because the sender is under the cab. Probably the same on a long bed truck with a 16 gallon tank.
     
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  11. Dave Somerville

    Dave Somerville Junior Member

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    I'd like to add my experience. `82 Sierra 1500 LB w/20 gal tank. Truck sat for 10 years and it was clogging up the fuel filter. Previous owner had for two weeks and was close but no cigar on everything then gave up. During removal, I could see they already changed the sender and put screw clamps on the hoses. I could just reach the clamps to loosen them and the weight of the tank pulled the hoses off (lucky). I took the sender out and there was no sock and the inside of the tank was incredibly rusty (in Phoenix, AZ) and there was mud on the bottom. I prepped the new tank but there's no way to get in there to reconnect the lines at the frame. The service manual has you disconnect the lines in step 2 and last during install. I can't figure out how they can get in there. So I too, was leaning towards unbolting the box and jacking it up so I can get in there. From what I've seen, I think the 16 gal tank vehicles can benefit from bed shifting/raising as then you can reach in from the back of the cab.

    Dave
     

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