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Thread: Bypass in-tank fuel pump for external electric fuel pump?

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  1. #1
    Thought it was unloaded.. mattmobile's Avatar
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    Bypass in-tank fuel pump for external electric fuel pump?

    Truck: 95, 4door, 4x4, W code CPI Vortec, SFK fuel tag. 130k miles.

    Problem: Steel line from sending unit rusted a pinhole to make a geyser; spits gas everywhere. Sending unit is corroded to 17 yr old tank; I'm not putting that old tank back up.


    Solution, so far: Ordered a bunch of new stuff, mostly OE style. List is a few posts below.





    MAIN QUESTION: See Post #8 - Need help with nylon fuel lines and fittings. PLEASE!! :)
    Last edited by mattmobile; 03-25-2012 at 11:23 AM.

  2. #2
    Registered User wagonmaster's Avatar
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    You don't have to use an in tank pump.

    It's really more about pressure than volume. You need to see what kind of pressure is required for your 95.

  3. #3
    5.7L VORTEC 350 blazin4low's Avatar
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    stock pumps usually put out 80-85psi unregulated

    you can flow what you want to pay for.....thing is your regulator will slow it down to what the injectors and motor wants. basically, think of it as the car that haul ass past you only to get stuck in traffic and you both get to the same point at the same time. buy a corvette and get to work at the same time as the blazer.
    http://i158.photobucket.com/albums/t114/VortecBlazer/sidredo.jpg
    Tuned by Bland Tuning
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    Marine Intake swap by me

  4. #4
    Thought it was unloaded.. mattmobile's Avatar
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    Haha, no money for a Vette right now. If I have to repair something on my Blazer, she usually gets an upgrade. She'll get an sbc at some point in her life but not anytime soon; I'm doing this with that in mind. Is there any way to do a feasible upgrade or should I just bite it and go with OE style parts?


    I found this for my motor:
    http://howstuffinmycarworks.com/Fuel...regulator.html
    Last edited by mattmobile; 03-25-2012 at 11:25 AM.

  5. #5
    Thought it was unloaded.. mattmobile's Avatar
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    Still doing research... I found that the CPI motor should be receiving 55-61psi with "key on, engine off."


    Any information on how to make this setup work is appreciated!!

  6. #6
    Zombie Killer 6SpeedBlazer's Avatar
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    your fuel pump/sending unit setup is no different that what gm ran since the early 80's on fuel injected engines.

    just replace it with OE parts.

  7. #7
    Thought it was unloaded.. mattmobile's Avatar
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    I ordered this stuff today. Everything is OE style except the pump/sender. It's a little different as the 95's pump and sender are usually sold as two separate units and installed in the tank individually; this one is preassembled with pump included and cheaper than buying individual parts. It says it only fits 95 4 door, so I'm hoping it's spot on.


    Pump/Sending unit - Spectra SP112A1H http://www.amazon.com/gp/product/B00..._ya_os_product
    Fuel Tank with lock ring kit - Spectra GM56A http://www.rockauto.com/catalog/moreinfo.php?pk=534553
    Fuel Filler Neck - Dorman 577945 http://www.rockauto.com/catalog/moreinfo.php?pk=2721516
    Vent Valve (x2) - Dorman 911001 http://www.rockauto.com/catalog/moreinfo.php?pk=1268109
    Hardware Kit - Dorman 55157 http://www.rockauto.com/catalog/moreinfo.php?pk=1027973
    Tank Strap Set - Spectra ST123 http://www.rockauto.com/catalog/moreinfo.php?pk=903018




    ANYTHING ELSE I NEED TO GET?? Here's a good exploded view of my tank setup:
    http://www.lmctruck.com/icatalog/cst/full.aspx?Page=127




    I'd like to get it as new and clean as possible up to the flexible part at the firewall. I'm only $369 deep now!
    THANKS!!
    Last edited by mattmobile; 03-25-2012 at 11:20 AM.

  8. #8
    Thought it was unloaded.. mattmobile's Avatar
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    UPDATE: Most of my parts have arrived!! Small dent in the tank from Rock Auto (pricks about it, too) but everything is pretty nice.


    I'm going with nylon fuel line from tank to front and front to tank. It is 3/8" (m16x1.5) supply, 5/16" (m14x1.5) return. I'm thinking I can just use fittings to attach the sending unit to the nylon lines, then use fittings on the supply line to attach an OE style FRAM 3727 filter. I'm buying 25' of each size to try to have a long, uninterrupted run; I'm going to try to tap in as close to the motor as possible.


    Dorman Fittings - http://www.oreillyauto.com/site/c/se...1715/C0290.oap
    Dorman Fuel Line - http://www.summitracing.com/parts/RNB-800-072/
    Fuel Filter Diagram - http://www.irv2.com/forums/f22/wh-fu...ook-31863.html (great cutaway pics, diagram of threads is 1/3 down the page)





    WHICH DORMAN FITTING IS PROPER TO ATTACH TO THE FRAM FILTER?
    Inverted flare - 785-404
    Pipe Thread - 785-406



    CAN I RUN THE NYLON FUEL LINE DIRECTLY FROM THE SENDING UNIT?
    OE steel line looks like this: http://www.napaonline.com/Catalog/Ca...15_0006464824#
    I want to use Dorman parts 800-078 (3/8") and 800-079 (5/16") from the o'reilly link to the nylon line from Summit (800-072 and 071). Is this OK?




    DO I NEED ANY ANTI-SEIZE or PTFE or anything ON THREADS?
    Last edited by mattmobile; 03-25-2012 at 11:19 AM.

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