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  1. #1

    Default Stumble picking up throttle

    Looking for help diagnosing pretty rough stumble when picking up the throttle mid turn. Clears up and pulls like a freight train about 1/3 the way down the straightaway. Just looking for some places to start.

  2. #2
    Join Date
    Dec 2008
    Location
    thedirtysouth
    Posts
    3,557

    Default

    could be several things , I had this happen to me one time and I tried every thing with the carb and did not fix it , wound up being that the fuel pick up in the fuel cell had got turned the wrong way , something that simple will run you crazy , I would check that first ...

  3. #3
    Join Date
    Aug 2012
    Posts
    125

    Default

    Float level, fuel pressure to high, return line to small, engine temp to cold, bad float in carb, air bleeds stopped up, what have you tried fixing so far.

  4. #4

    Default

    tried to dail back fuel pressure at the track between heat and feature, either wasnt enough or its not the problem, spoke with bill pink wh built the carb he advise to verify floats at 3000-3500 rpm as well as set fuel pressure there. Im no carb guru, know how to bolt one on and change jets, so didnt really have a clue where to begin looking.

  5. #5
    Join Date
    Aug 2012
    Posts
    125

    Default

    What type of fuel pump are you running? stock location and if so what type is it or belt drive?

  6. #6

    Default

    kse tandem driven off oil pump, return style regulator -8 return line, -10 from cell to pump , -8 from pump to reg.

  7. #7
    Join Date
    Aug 2012
    Posts
    125

    Default

    Is the return port in the pump blocked off ? Regulator before or after the carb?

  8. #8

    Default

    yes return port blocked, regulator is plumbed before carb

  9. #9
    Join Date
    Aug 2012
    Posts
    125

    Default

    it almost sounds like the regulator can't bypass enough fuel and it is forcing the fuel to overflow the carb. You might have a bad regulator or return line stopped up or maybe crimped off. A lot of the regulators are plumbed at the end of the fuel log so the carb will see full volume and it is as close as can be to the carb for the quickest response in pressure changes.
    Last edited by Mopar DLM; 03-30-2021 at 12:17 PM.

  10. #10
    Join Date
    Nov 2012
    Location
    Wisconsin
    Posts
    3,070

    Default

    Mopar DLM is correct about plumbing the regulator.

    Whay do your plugs look like...sounds like you are dead rich on fuel.
    Member of the Luxemburg Speedway Hall of Fame
    Class of 2019

  11. #11
    Join Date
    Aug 2012
    Posts
    125

    Default

    Not sure if your regulator has an idle setting for pressure or not but with the belt drive pumps I like to crimp the return line till pressure comes up to full normal race pressure (7-7.5 psi or whatever your carb guy calls for) then set the floats.

  12. #12

    Default

    ordered the new high dollar areomotive dual adjustable, waiting for it to arrive then will confirm float levels and going to disassemble return line and flush to confirm good flow through line.

  13. #13
    Join Date
    May 2007
    Posts
    2,868

    Default

    Thats a great idea Mopar, that could solve a lot of carb issues !

    Just say no...

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