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Small engine repair question

Discussion in 'Off Topic Threads' started by Claymuncher, Apr 7, 2012.

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  1. Claymuncher

    Claymuncher Member

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    My small engine on a sprayer surges up and down, it has the spring throttle on it to keep the rpm even and I have turned every adjustment screw. Any one have a suggestion?

    Thank you in advance

    CM
     
  2. motordoctor

    motordoctor Shoji Tabuchi in Branson

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    could be too lean on the carb. try some carb spray into the air intake. might have dirt in it. could be other things also but start with the easy stuff like spark plug dirty and such
     
  3. scooterbum

    scooterbum Active Member

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    2 or 4 stroke?
     
  4. grntitan

    grntitan Well-Known Member

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    What kind of engine is it? Does the carb sit on top of the fuel tank? If it does sit on top of the tank, the gasket between the tank and carb can get worn and then it sucks air causing rough idle. Like motordoc said above, also check for clogged fuel filters or clogged fuel pickup tube. I think it would help if you were more specific on the engine brand, size and style.
     
  5. Claymuncher

    Claymuncher Member

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    I should have Known better than to ask a question without enough info. I appreciate the knowledge and will jump into it this afternoon, the simplest first.

    3.5 4stroker

    CM
    [​IMG]
     
  6. 320090T

    320090T Well-Known Member

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    The motors a 1994, time for a tuneup, carb rebuild, and and an oil change. Don't forget to put some oil in the starter rewind nut hole.
     
  7. Claymuncher

    Claymuncher Member

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    320090T : What you are sying is I should let the ones that no what they are doing do it? Nothing is easy it seems some times! I will try a few of the suggestions to get me through the year and then take it in this fall. It gets used but once a year.

    Thanks

    CM
     
  8. Raybren

    Raybren Member

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    Had a Briggs 8 hp engine on a riding mower that surged up and down. Took the carb apart and there was a spring under the float. I removed the spring and problem solved. Ray
     
  9. grntitan

    grntitan Well-Known Member

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    SSTG,

    Them damned old extra parts...............LOL
     
  10. motordoctor

    motordoctor Shoji Tabuchi in Branson

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    i think that carb sits right on the gas tank. the gasket between might be bad. check the filters also
     
  11. Bvr Tail

    Bvr Tail Well-Known Member

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    The gasket many are referring to is probably a diaphragm. Older engines used these along with a small spring and collar to pulse-feed fuel to the engine.

    Often, with time, they weaken or harden, and don't work as well.

    Take notice as to the position of the spring and collar to the diaphragm when replacing.

    Also, with the heat of a small engine, the surface of the fuel tank can warp, and the diaphragm will not seal as well, or not at all.. In this case, a replacement tank is necessary.

    I've been away from them for a while, so I hope this helps.
     
  12. halfmile

    halfmile Well-Known Member

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    If you take the carb off and clean the pickup tube you might have better results. I had one get splugged up with paint residue, and starve the carb.

    Also let the engine warm up at a lower throttle setting before you make it work.

    HM
     
  13. omgb

    omgb Well-Known Member

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    I have the same engine on a mower. It surged too. I had the carb rebuilt and it fixed it.
     
  14. Twinbirds

    Twinbirds TS Member

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    seafoam, make sure all mounting screws are tight then use seafoam.
     
  15. Dr.Longshot

    Dr.Longshot Banned Banned

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    That gasket between the carb and fuel tank is the Fuel Pump, and they are hard to start when thyey go bad.

    Gary Bryant
    Dr.longshot
     
  16. Pull & Mark

    Pull & Mark Well-Known Member

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    Try Seafoam first, then the carb rebuild if all else falls. Next year store all your gas type motors with Seafoam mixed with the gas before Winter hits, or you can run the engine and gas tanks dry!!! Good Luck and break em all JEff
     
  17. JIM SIMS

    JIM SIMS Member

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    Clean out fuel tank,add premium gas w/stabil,especially if you forced to use
    10 0/0 ethanol gas.Mine did the same thing
     
  18. Claymuncher

    Claymuncher Member

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    Thanks for all the info, I am still working on it. So far I have taken it apart, cleaned up everything, checked for gasket leaks, found a new spring for the carb, changed fuel filter. Still surges. Must need the carb rebuild but I am going to let someone else do that. No easy fix but I gave it a shot.

    Thanks again
     
  19. cubancigar2000

    cubancigar2000 Well-Known Member

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    run some seafoam through it
     
  20. Rem29

    Rem29 Member

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    Turn the gas off. Remove the float bowl from the bottom of the carb. This is done by removing the high speed jet in the "nut" then turning the nut on the bottom of the float bowl counterclockwise with the appropriately sized wrench (NOT pliers). NOTE the position of the flat on the bottom so you can return it to the same position. That "nut" is actually part of the jet system. Look very closely at it near the top and you will see a tiny hole on the side ~ 10 to 20 thousandths. get a very fine wire like that in a twist tie and clean out that hole then spray the entire assembly with carb cleaner. Carefully put the float-bowl back on the carb assuring the gasket is in the proper place. Snug the bowl "nut" down then screw in the jet all the way to gentle seat. Back the jet out 3/4 of a turn from seat, turn on the gas, check for leaks then give 'er a go.
     
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