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Fuel tank/sending unit data needed

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by dyeager535, Apr 27, 2003.

  1. dyeager535

    dyeager535 1 ton status Premium Member

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    Anyone have a C/K 10/20/30 fuel tank laying around?

    I'd like to know the depth of the tank. Either the "normal" tank, or the optional dual tank. I *think* they are the same size, or at least appear to be the same depth, but I haven't been able to look real closely.

    Kinda thinking all sending units are the same depth, but need to know the depth of the truck tanks to compare to the K5 tank. The part number differences for like year sending units perhaps being based solely on the sending unit fitting orientation, at least among the same GVW/engine combination.

    If the sending unit fitting orientation is the only difference, and not depth, a 1987 TBI passenger side tank sending unit would make a TPI conversion easier. Having the sending unit fittings on the drivers side, which is where the fuel lines need to be on that swap, would save a 90* bend, as well as having to route it over the rear crossmember.
     
  2. outlaw612

    outlaw612 1/2 ton status

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    I just took the sending unit out of an old saddle tank, but I dont have it here to measure.I can measure from the outside on the one thats on my truck if that will work.
     
  3. marine_enlisted

    marine_enlisted 1/2 ton status

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    I just measured a sending unit that came out of an '86 16gal tank. From the bottom edge of the top plate to the bottom of the strainer sock is 10.5". /forums/images/graemlins/usaflag.gif
     
  4. dyeager535

    dyeager535 1 ton status Premium Member

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    Dang, and it was such a good idea too /forums/images/graemlins/smile.gif

    The K5 sending unit is 12" tall measured the same way you did. 2" off. rrr.

    Thanks for checking, are there larger saddle tanks than that, like 18 or 20 gallons?
     
  5. 79Jimmy

    79Jimmy 1/2 ton status

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    12" Is that for the 31 or 25 gallon tank. I assume the 31 since I reused the sender for my 25 gal tank when I switched to a newer 31 gal. And according to the LMC catalog the height difference from 25 to 31 is exactly 2". I just straitened out some of the bends to make it draw from the very bottom and read empty accurately. It was easy and have had zero problems in over 2 years now. Just have to be carfull not to kink the line. The gage reads full for quite a while but who cares, I only need to know when it's time to go to the bank and then fill up /forums/images/graemlins/grin.gif

    James
     
  6. marine_enlisted

    marine_enlisted 1/2 ton status

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    Yes there are larger saddle tanks. Shortbeds run 16 gal. and I'm pretty sure long beds are 20 gal. Come to think of it when I was changing my fuel system over from carb to Vortec I bought a sender from a salvage yard, they said it was from a truck. It must have been from a long bed, becuase I had to shorten it about 1.5" . I just cut the pump mount off shortened the return tube and tacked the pump mount back on. I had to re-bend my float arm ,but I got it pretty close. If your using carb couldn't you just shorten the pick-up tube and splice in a piece of rubber fuel hose? Or if you don't think that will be solid enough. you could use a compression union. /forums/images/graemlins/thumb.gif /forums/images/graemlins/usaflag.gif
     
  7. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Why not just use a 1987 or later TBI sending unit for the TPI conversion using the TPI fuel pump if you are doing this to a truck or if you are doing it to a blazer then just do the rear inlet fuel rail which will be on the passenger side just like the fuel lines are for a TBI?
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    Yeah, guess hacking a sending unit up wouldn't hurt anything, except finding an '87+ TBI saddle tank sender to practice on is probably fairly costly /forums/images/graemlins/smile.gif

    Neat idea though, just stretch the whole thing. I'll keep my eyes open for a later truck with the dual tanks.

    And yes, 12" is the depth of the 31 gallon K5 tank. This is a TPI swap, so it's got to be as close to the bottom of the tank as possible, and fit the fuel pump.
     
  9. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    For what it's worth, I took a TBI sending unit out of a SWB 87 truck, it was exactly the same length as my Diesel LWB tank which I used for a guide (capacity? don't know...). This in turn was the same length as the sending unit in my 23 gallon (small) K5 tank I use now... Maybe I just got lucky...
     
  10. dyeager535

    dyeager535 1 ton status Premium Member

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    [ QUOTE ]
    if you are doing it to a blazer then just do the rear inlet fuel rail which will be on the passenger side just like the fuel lines are for a TBI?

    [/ QUOTE ]

    Because I've already got the complete TPI setup, and any change to it would require more time/money than just running the lines up the drivers side. Gotta replace a fair amount of the line anyways, so it's not like it's extra work.

    Fuel rails are different parts driver/passenger side (not interchangeable easily), the steel lines from the rails would probably hit the firewall, and there would be no support for the steel fuel lines (like there is stock) where the flex lines attach to join the frame fuel lines to the fuel rail lines.
     

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