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Which is better? Internal or external fuel pump.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by keith, Aug 20, 2001.

  1. keith

    keith 1/2 ton status

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    I can use a 88 gas tank for my new fuel Injection or use the external holley fuel pump that came with the kit. The Commander 950 fuel injection is set at 21psi. What is the stock pump put out? Can I run the internal and put the external in line and get power to it if the internal fails.? If the internal pump fails can gas still flow through it?

    79 Blazer 6"lift 38 SX's locked/4:56 <a target="_blank" href=http://www.keith.rockcrawler.com>www.keith.rockcrawler.com</a>
     
  2. DesertDueler

    DesertDueler 1/2 ton status

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    The internal pump psi is somewhere between 12 and 15 psi. Not enough.

    86 Blazer 4"lift 35" MTRs locked front, still 1/2 ton axles.Other vehicles 69 Firebird with 525 hp,and a 70 GTO www.geocities.com/modifierperformance
     
  3. blazer72

    blazer72 1/2 ton status

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    you could run the TPI pump in the tank In tank pump run cooler than the others so last longer.
     
  4. k5king

    k5king 1/2 ton status

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    <font color=green>i don't think that the holley pump is set up to " pull " fuel from the tank,,it is meant to "push" it to the fuel injection and be gravity fed. i think that if you read the instruction's( i know, i know,,lol) you'll see that it has to be mounted lower than the tank itself.I.E. the frame rail to keep it low and out of harm's way. plus the stock pump probably doesn't even come close to the fuel pressure requirement's your gonna need to run that system. do the holley,you'll be much better off.</font color=green>

    <font color=purple>ANYBODY LOSE THEIR JEEP????????[​IMG]
    I JUST FOUND ONE UNDER MY BLAZER!!!![​IMG]
    [​IMG][​IMG]</font color=green>
     
  5. Mudzer

    Mudzer 1/2 ton status Author

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    Keith,

    I would agree with Blazer72, the in-tank pump with a trap door above the sending unit (for future replacement) is the best route. As Ken said, the in-tank pump lasts much longer by running cooler. You can buy an in-tank Walbro High Pressure pump for the same money of the Holley. I realize you already have the Holley Pump, but put it on Ebay and sell it. See, the reason you are installing Fuel Injection is to help out at angles, correct? Well, if you install an external pump you are in fact using a "push pump" and rely on gravity feed. This means, when you do not have your stock sending unit submerged in fuel, it will starve and cut out, or possibly kill the engine. This is not good! Now, the stock Fuel Injection tank has a baffle which holds fuel during those steep or off camber climbs. This will constantly keep fuel pressure high as needed. You may want to talk to Shawn or Steve Fox, both have installed the Walbro pumps (I'm pretty sure). You may want to hold on to your external pump just for trail spare. You could plumb in a quick coupling or something and make it easy for future trail maintenance. But, if you have a trap door above the stock sending unit in the tank, you can change out fuel pumps in a hurry. You may never have to change one, but I always like to plan ahead! Good luck dude. So, when is the next Tellico run?

    Mudzer 1978/91 K5
    <font color=blue><a target="_blank" href=http://www.mudzer.rockcrawler.com>www.mudzer.rockcrawler.com</a></font color=blue>
     
  6. BurbinOR

    BurbinOR 3/4 ton status

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    Well, the external inline pumps like I run (a Bosch) are meant to be external and heat is a non-issue to them. I prefer mine where it is tucked into the frame rail above the drivers side rear wheel, makes it easy to swap out if needed. Figure if you have the opportunity to go in-tank or out, go with the one that will be easiest to maintain. Just my $.02

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     
  7. pcorssmit

    pcorssmit 1/2 ton status

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    I prefer an in-tank, you might look into a TPI pump or the Walbro (I have no exper. w/these). Stock TBI pump is not adequate for 21 psi.

    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  8. Cmoe

    Cmoe 1/2 ton status

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    What is the rate that the Holley on the recieving side....... I think that the way I would go is to use both if possible.....The pump in tank is at the rear and mount the Holley mid way so you don't loss any pressure....... Just my 2 cents worth

    C'moe

    <font color=black>the blazer is "Back in Black"
     
  9. Executioner

    Executioner 1/2 ton status

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    Which Bosch pump are you using ?
    Any specs. or p/n would be helpfull
    Thanks alot
     
  10. BurbinOR

    BurbinOR 3/4 ton status

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    Executioner, it is Bosch part number 0-580-464-008, this pump is actually a Jaguar part number...........my TPI guru has been using these for years on all his 130+ TPI conversions.

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     
  11. HarryH3

    HarryH3 1 ton status Author

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    I've got a Bosch pump installed inside the frame rail as well. Don't know the part number off hand, but it's from a V12 Jaguar application. It was recommended by a guy that road raced Corvettes. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  12. realsquash

    realsquash 1/2 ton status

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    Use the 88+ tank and the in-tank pump! You will want to get a pump meant for a TPI firebird/camaro, but it will plug right in no problem. The in-tank pump is sooo much better in all ways except changing it!

    Squash
    <a target="_blank" href=http://www.trailrunners4x4.org/users/realsquash>http://www.trailrunners4x4.org/users/realsquash</a>
     
  13. Executioner

    Executioner 1/2 ton status

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    Thanks, any idears where to get a NEW (Brand new, never been used) one for cheap ?
    Do you carry a spare when you go far from home/wheeling ?
    My Holley/Carter is starting to make more noise.
     
  14. HarryH3

    HarryH3 1 ton status Author

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    The words cheap and Bosch typically aren't found in the same sentence. [​IMG] The pump I'm using cost right at $200. [​IMG] This was probably 13 years ago, when EFI was still new, so the prices may be a bit more reasonable these days.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  15. BurbinOR

    BurbinOR 3/4 ton status

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    I paid $130 for a brand new one...........having a source that is in the auto repair business helps a lot. List price is like $150 for that pump.

    No, I don't carry a spare with me, I trust the reliability of my install [​IMG] and the unit!

    <font color=blue>'79 ONE TON TPI K5 - See it at---&gt;<a target="_blank" href=http://www.blazzinor.rockcrawler.com>www.blazzinor.rockcrawler.com</a>
     
  16. Executioner

    Executioner 1/2 ton status

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    Am I reading that right, you have been using that pump for 13 years ?
    That's very good life so far (nock on wood).
    Thanks to both of you, the price search continues.
     

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