Fuel pump rod

Discussion in 'The Engine Bay' started by Wes Harden, Jun 22, 2020.

  1. diesel4me

    diesel4me 1 ton status Premium Member

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    Non-Ethanol fuel won't boil at a lower temperature like fuel laced with ethanol will too--if you have access to non-ethanol gas maybe try that and see if it helps..
    Some of my old air cooled engines don't run well at all on the 10% ethanol crap sold here,especially when they get hot on a summer day thats 80+ degrees out..
     
  2. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    not in Kommiefornia, In Havasu I can buy some good gas, 105 octane, is 5 a gallon last i purchased. (truck really likes this stuff)

    My Manx type runs ok, jetted fat as hell too. I use Lucas alcohol fuel additive in that, and only supper.
     
    Last edited: Jun 23, 2020
  3. blazer74

    blazer74 Member Premium Member

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    Q jet won’t like 14 psi.
    Like I mentioned I tried a stock 3 line pump incorporating the return and it did not work so I don’t think the regulator with the bypass on the frame will solve the problem.
     
  4. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    yes I had 2 stock pumps with return a current one performance pump w/o. regulator will set fuel pressure at 7.5 to start. Truck just won't run well 4th under a light load 40 to 55 mph on a mechanical pump. I am beginning to believe the rpms are to low to move enough fuel. Delfi shows the exact same pump 1977 6.6 k20, and 1985 K5 5.7 with 700r4 don't get it, alcohol ?
     
  5. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    tank is full atm. Runs ok with electric, thou current electric pump is not up to a heavy load, I think the first pump was just barely adequate, until it got hot dead heading at idle, and was damaged.
    thats my theory anyway.
     
  6. blazer74

    blazer74 Member Premium Member

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    10% Ethanol is more volatile. Vaporizes quicker, runs leaner. Upsize 1 or 2 jet sizes for a richer mix.
    Electric pump pressure lessons the effects.
    I’ve owned my K5 since 1988 and never had an issue until the ethanol fuels showed up. Just like that stumble, hesitation, falling on its face WOT and hard starts.
     
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  7. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    Ordered a jet kit from this place
    https://www.carburetion.com/Rochester.asp

    My carb has 69 primary jets. Going to 71 and leave the same rods. Also got a bigger needle and seat current is .107 new will be .147.
    Kit has springs and other goodies.
    After reading about edlebrock q-jet perfomer, I wish I had got one. I got stock replacement back when you could get them
     
  8. blazer74

    blazer74 Member Premium Member

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    I would make one change at a time so you know what does what. Real easy to try the filter first.
     
  9. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    Got home today and enough of the fittings I ordered had arrived to remove the steel pump to carb line, and replace with braided hose and -6AN fittings. I also removed the carb inlet fuel filter and left it out. I went out for a short test drive. Gauge reads 3/4. Electric pump off. Very slight uphill in 4th 42 mph @ 1500 had run poorly in this situation last test, seemed ok but I was behind a very slow truck. Inconclusive in my book. Freeway on ramp, starts down then up 2-3% grade, once 50ish mph accelerating moderate starts to stumble cough spit and no power. Turn electric on with a few seconds I can accelerate up 75 no issue 1-2% grade. Get off at next off ramp, shut off electric drive home no issue. Some moderate to mild acceleration mixed. The removal of filter seemed make a small improvement. Thou atm I only have a filter at tank before electric. I will be driving up to the high desert @ 20 miles from KOH tomorrow.
     
  10. Wes Harden

    Wes Harden 1/2 ton status Premium Member

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    I drove to my brother's 120 mile round trip. Started with just over 1/2 tank by gauge, got home with less gas then the recent problem at Costco gas station. Today I got some Qjet goodies. Made 3 changes to carburetor.
    1. I upped the inlet seat from .107" to .147"
    2. upped the primary jet from 69 to 71, reused primary rods .037b
    3. change the power spring(primary metering rod spring) to 3in Hg 1.110" l
    Truck ran a lot better idle smoother I needed to turn the idle mixture screws in @ 3/4 turn. Drives around town with ac on great even under a load w/o the electric pump.
    Still won't get on the freeway with out the electric.
    Still need to add return style regulator in line, not finding a good spot. I have to upgrade the electric pump also. Will do these 2 mods this weekend. Wifey stills needs it for errands
     
  11. JoshHefnerX

    JoshHefnerX 1/2 ton status Premium Member

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    Sounds like progress
     

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