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Dauntless Fuel Gph

Discussion in 'Early CJ5 and CJ6 Tech' started by Steve's 70-5, Jan 2, 2021.

  1. Jan 2, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    Was looking for a in-line fuel pump for my Jeep, to run a carburetor. Was at O'Reilly's and they looked it up and came up with a Mr. Gasket pump that flowed 35 GPH, which I think is to much. Found this Holley video on calculating fuel usage on a engine. The first on on the page.

    Fuel Pumps Technical Support - Holley

    According to the video and the Dauntless engine having 160 HP, found info in the FSM. I would need a 14GPH fuel pump. Yes there is a fuel line return, but I see no reason to pump more gas that needed. Yes add a little for CYA factor.

    I have no idea what the mechanical pump is rated at and today, the way parts are made to fit many application, it is hard to say what you are getting.

    Anyone ever calculate this number
     
  2. Jan 2, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
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    I have never considered the GPH number. Realize that's a total for unimpeded flow, which is fine as long as the number is larger than you need. There should also be a pressure number, which is something like 3-5 psi for a carburetor. Some carburetors are more sensitive to fuel pump pressure than others. The TSM for your Jeep should have a spec for fuel pump pressure; I know the later AMC-era books do.

    No way I'm going to watch their video. Do you have a link to a spec page, in text?
     
  3. Jan 2, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    Here is the formula

    GPH=(Max HP x BSFC)/6

    BSFC is .5

    GPH=( Max HP x .5) / 6
     
  4. Jan 2, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    BSFC Brake-specific fuel consumption - Wikipedia

    Why 6?

    Suspect you'll find that any of these pumps has plenty of fuel delivery potential for your engine. Also suspect the GPH is irrelevant unless you're running a 700 hp engine on the track at full throttle most of the time.

    What does your TSM say about fuel pressure? Which pump are you looking at? Link?
     
  5. Jan 2, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    6 is the average weight of a gallon of gas.

    Just starting to look for a pump, nothing picked out yet.
     
  6. Jan 2, 2021
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

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    Twin2 likes this.
  7. Jan 2, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    You are using a 18 GPH pump and with the way fuel lines may be run, there is probably some loss in GPH. Been running it for 5 years and I guess there has not been a fuel starvation issue. Looking on Holley's Web site, the smallest pump they offer is 25 GPH.
     
  8. Jan 2, 2021
    FinoCJ

    FinoCJ 1970 CJ5 Staff Member

    Bozeman, MT
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    I don't have access to my FSM at the moment, but when I went through my fuel pump issues years ago, I remember that the FSM has specific data for the fuel flow volume and pressure requirements for the v6....maybe someone can take a look and post the numbers....
     
  9. Jan 3, 2021
    jeepdaddy2000

    jeepdaddy2000 Active Member

    Eagle Point oregon
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    GPH should be a moot point. I can't think of an electric fuel pump on the market that won't flow more than you carb will pull. Excessive GPH doesn't exist, as the carb float will shut down flow when it closes.
    As stated above, pressure is the issue. Excessive pressure can force a higher float level, causing poor performance at best, flooding at worst. Most carbs can handle 5-7 PSI, with Webbers in the 3PSI range. Pressure can be controlled (mechanical or electric) with an inline pressure regulator.
    On a side note, what is the issue with your mechanical pump? They usually work just fine and don't need any sort of roll over or other safety kill switch (which should be a part of your electric pump installation).
     
    fhoehle and colojeepguy like this.
  10. Jan 3, 2021
    Steve's 70-5

    Steve's 70-5 Active Member

    Louisville, Ky
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    What I am looking for is GPH. I am installing EFI, using A FiTech Force Fuel

    50004 Force Fuel System - FiTech Fuel Injection

    Going with Electric in-line fuel pumps, looking for info on how much fuel the engine will consume so I can find the right pump
     
  11. Jan 3, 2021
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    It's not an exact science as far as having to hit just the right psi and gpm since your pump from the tank to the command is basically just a lift pump.
    you just need enough to not have the half gal reservoir go empty when you hit the quarter mile.
    On mine I might go gravity feed with a check valve in the line. the high pressure pump will basically be in or adjacent to its little tank at the frame under the driver's tank.
     
    Last edited: Jan 3, 2021
  12. Jan 3, 2021
    Jw60

    Jw60 Sitting up n buckled down. 2024 Sponsor 2023 Sponsor 2022 Sponsor

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    Some quick reading with the competition looks like Tim's pump is fine to lift to your efi pump for stock dauntless hp.

    https://www.summitracing.com/parts/hpf-40004

    340lph for 800hp
    Your system is also 340lph
    So 85 lph for 200hp
    21ish gpm @ 200hp
     
  13. Jan 4, 2021
    jeepdaddy2000

    jeepdaddy2000 Active Member

    Eagle Point oregon
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