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Sputtering And Stuttering

Discussion in 'Early CJ5 and CJ6 Tech' started by Norwajun, Nov 17, 2023.

  1. Nov 18, 2023
    45es

    45es Active Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Naches, WA
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    Do another picture. That one is useless.
     
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  2. Nov 18, 2023
    vtxtasy

    vtxtasy oldbee 2024 Sponsor 2023 Sponsor

    Tucson, AZ
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    A post by SweetPea reminded of the vented/non-vented gas cap. That resembles the issue.
     
  3. Nov 19, 2023
    givemethewillys

    givemethewillys Been here since sparky ran it. 2022 Sponsor

    New Kent, VA
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    It's very hard to tell from your picture, but the stock fuel line makes a tight u-shape out of the bottom of the fuel pump. If the tube isn't crushed, that might be normal.
     
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  4. Nov 19, 2023
    Norwajun

    Norwajun New Member

    High desert of Socal
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    Aug 24, 2023
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    I'll try to get a better photo today. Light was terrible yesterday. It makes a U bend, but in the arc the tubing is flattened, creating what looks like a reduction in diameter. Really hard to see unless you're looking for it.
     
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  5. Nov 19, 2023
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    If it is flattened enough it will definitely restrict flow.
     
  6. Nov 19, 2023
    Norwajun

    Norwajun New Member

    High desert of Socal
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    Aug 24, 2023
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    If you look at bottom of photo, that's the fuel line arcing from fuel pump. The apex of that bend is flattened, reducing diameter of line by half, at least.
     
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  7. Nov 19, 2023
    PeteL

    PeteL If it wasn't for physics, and law enforcement... 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Hills of NH
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    But when the fuel passes into the carb, the orifice of the float valve is measured in thousandths of an inch, and the volume of flow that needs to pass is tiny. (?)
     
  8. Nov 19, 2023
    Fireball

    Fireball Well-Known Member 2024 Sponsor 2023 Sponsor 2022 Sponsor

    Pullman, WA
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    This. A Dauntless at cruise speed is not a 500hp full throttle big block that can easily be fed with a 3/8" fuel line. The restriction caused by that is not your root problem. It sounds more like a clogged filter, no vented cap, or failing fuel pump. It's not the time a year for vapor lock or I would also add that to the mix.
     
  9. Nov 21, 2023
    Glenn

    Glenn Kinda grumpy old man Staff Member

    Apopka, Fl
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    But.....flow gets restricted when the line isn't perfectly round and then add to that the resistance from the bend itself?
     
  10. Nov 21, 2023
    Norwajun

    Norwajun New Member

    High desert of Socal
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    Aug 24, 2023
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    The cumulative knowledge here is absolutely crazy. I'll start with a new fuel filter.

    Thank you all for the assist!
     
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  11. Nov 21, 2023
    HellaSlow

    HellaSlow Member 2024 Sponsor

    Burbank, CA
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    Dec 28, 2022
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    As I've learned on here, its best to systematically work your way through the problem instead of jumping around. Helps you really narrow down and eliminate possibilities. I'd start at your gas cap and work your way forward. This way, you're starting with the easiest/cheapest fixes and working toward the more complex (albeit still easy enough) fixes.

    1. Start with making sure you have a vented gas cap.
    2. Blow the fuel lines out and maybe drain your tank to see if there are big chunks or debris.
    3. Make sure your fuel pump is free of debris as well.
    4. If your fuel filter is attached via rubber hose clamped to metal line. Either add a bubble flare, an extra clamp (or 6), or think about replacing the filter with one you can "hard line" into your system. The "sucking" side of the fuel lines (everything between the tank and pump) creates a huge amount of negative pressure that could be sucking air into your lines without leaking gas.
    5. if you have a metal fuel filter, make sure it's not too close to your exhaust, manifold, or right up against your engine. They can become heat syncs and cause the fuel to boil in the lines. While you're at it, do the same check on all your lines to make sure they're good and far from heat.
    6. Blow through the lines between your pump and carb (with them off the vehicle) to make sure nothing is trapped.
    7. Pop the top off the carb to make sure the float bowl area is free of debris and make sure the float is adjusted correctly.
    8. If you have never done so, Take a stab at removing the carb all together and cleaning it out yourself. It's easier than you think and its a great way to get accustomed to your vehicle. Carbs need cleaning every couple seasons anyway so it'll save you a ton of $$ getting used to doing it yourself.

    Oh and when you're done, Consider adding some seafoam to your fuel at every fuel up. It helps with breaking down any varnish build up, and helps clear out microscopic crud from your fuel system and carb. And helps keep it clean and happy longer.
     
    Last edited: Nov 21, 2023
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