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Fuel tank swap for TBI??

Discussion in 'The Garage' started by cok5, Nov 10, 2005.

  1. cok5

    cok5 Registered Member

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    I think I read somewhere that if you go from carb to TBI you need to swap tanks or run over 1/4 tank of gas??? Is this correct? I have a 85 Blazer (Jimmy actually) and plan to convert it to TBI, what tank do I need and what pump.....just the stock one? Thanks
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Stock pump is fine, an aftermarket tank is better than stock though.

    Stock tanks use a plastic sump held to the tank bottom, typically it breaks off and is worthless.
     
  3. loafer

    loafer 1/2 ton status

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    I swapped from carb to TBI and I kept the stock tank and stock sending unit. I use an external fuel pump though. If you want to use an in-take pump you will need to replace the sending unit.

    Don't use the stock 1/4" fuel return line though, run a new line that is either 3/8" or 5/16". The 1/4" stock line is too restrictive and will cause pressure to build up on the bypass side of the regulator.

    I also added a 3/8" fuel return fitting to my tank and plugged off the stock 1/4" pipe on the sending unit.
     
  4. TheEmissary

    TheEmissary Registered Member

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    87-91 fuel tank

    The 87-91 fuel tank for TBI K5s will interchange with the older vehicles if using the filler neck and related hardware.
     
  5. u2slow

    u2slow 1/2 ton status

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    TBI tanks have baffling to prevent fuel slosh from starving the pump. Stock tanks have plastic baffles that break. Most aftermarket tanks use steel baffles.
     
  6. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    If i were you, i'd just hook it all up and see how low you can run your gas tank before it starts surging...

    My old TPI setup would surge for gas under hard accleration or cornering under 1/2 tank or so...
    When i swapped in my GenIII 6.0L i didn't want to be experiencing the same issues of starving my hi pressure fuel pump... so i installed a small surge canister.. I mounted it up near my heater core in the engine compartment. An A/C canister could be modified to work as a good surge tank.

    Heres what i did:
    1 surge canister with 3 fittings on top and 1 fitting on bottom:
    Low pressure inline pump to feed the surge canister.
    Return line from the very top of the canister returns to the fuel tank.
    Outlet out of the bottom of the surge tank feeds my hi pressure efi fuel pump...
    Then the return line for my injection dumps back into the surge canister.
     
  7. btolenti

    btolenti 1/2 ton status

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    This is what I did. I lucked out and found a tank and sender and pump on ebay for 100 bucks.
     
  8. u2slow

    u2slow 1/2 ton status

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    Suburban pump/sender works on the 31-gallon tank - in case you can't find one from a K5.
     
  9. beastofablaze

    beastofablaze 1/2 ton status

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    Definetly go with an inline pump... Not only is it easier to pull out if it ever goes bad but you'll be taking an electric pump out of gasoline. I know they rarely if ever blow up but **** happens and its better to cover your ass now then burn it later.
     
  10. azblazer

    azblazer 1/2 ton status Premium Member

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    www.rockauto.com sells an aftermarket tbi tank for around 9-95 bux and the ride. Until i have time to make a real tank skid as the factory one buckles all the time i buy my tanks from them. The next time though i'm going to have a fab shop cut off the saginaw fittings on the sending unit and tig weld on AN fittings so i can clean up the frame a bit as i have used donor 87 up K5 lines on my last two conversions. My 79 has been converted for close to 5 years now and i have never had a pump problem. just stay away from the factory tanks as the phenolic plastic baffle will break and knock the pump off the sending unit. The stock tbi feed lines to the tb unit are about $48.75 a piece from gm. However if they are not secured to the back of the head they won't last long. Turbo city sells saginaw to nipple adapters for $9.99 a piece....then all you need is a couple clamps and some good quality fuel injection line....its still a rubber hose but the sidewall is stiffer than the normal 3/8 rubber hose.

    Doug W.
     

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