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Honda GX390 not running at full speed?

Discussion in 'Mechanic and Repair' started by cariboulou, Jan 17, 2012.

  1. cariboulou

    cariboulou LawnSite Member
    Messages: 160

    Just took my pressure washer out of storage from about 2 yrs, drained old fuel, took carb apart and cleaned with carb cleaner including jet. Engine starts and runs great with choke at 1/2 position but when open choke and full throttle it dies within 3 seconds or so. Ive cleaned carb 2x and refilled with fresh gas. Could it need a valve adjustment? I didnt see a lot if any oil in carb? It runs good with carb at full throttle and 1/2 choke for as long as i need it to. Any suggestions?? Its a honda gx390 13hp.
     
  2. cariboulou

    cariboulou LawnSite Member
    Messages: 160

    just read the earlier post about cleaning carb, but I failed to push out nozzle and clean that...could that be problem? Ill try again tomorrow.
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Could be Lou, If all else fails you can get a new carb and other pressure washer parts HERE.

    I haven't had any issues with these Chinese carbs.....
     
  4. cariboulou

    cariboulou LawnSite Member
    Messages: 160

    Just cleaned carb for the 3rd time and removed and cleaned nozzle and cleaned everything well, but still only runs good at 1/2 choke. Could this be a carb issue, I've never adjusted valves? where can i find specs for valve clearance?
     
  5. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029


    It sure sounds like something isn't fully open inside the carb,
    Have you replaced the spark plug (BPR6ES) ? I've seen fouled/weak firing plugs cause a issue such as this....


    Valve adjustment if you want to check;

    [​IMG]
     
    Last edited: Jan 17, 2012
  6. cariboulou

    cariboulou LawnSite Member
    Messages: 160

    the spark plug?? wonder why? I'll change that out to see if that helps. then check valve adjustment. If still not running right, ill have to order replacement carb. I just assumed that it was a carb issue, but it runs great at half choke so I know fuel is getting though ok. Ive cleaned it 3x! thanks for help!
     
  7. cariboulou

    cariboulou LawnSite Member
    Messages: 160

    when im looking at valves...which one is intake and exhaust?
     
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,329

    Remove the fuelbowl drain screw. Check the gas flow.
    You may have a clogged fuel screen in the tank.
    Posted via Mobile Device
     
  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Ditto what Slapper said ^^^^

    The intake is the one closest to the carb....
     
  10. cariboulou

    cariboulou LawnSite Member
    Messages: 160

    ok will do, tried a new spark plug but still not running right. I cleaned out jet and nozzle holes with a small wire to make sure they aren't clogged and ran air through again. Still not good. Definetly not clogged, should i run machine with drain screw out and plugged with thumb. everytime i've taken carb apart there is fuel in the bowl.


    Now I can run machine with no choke and full throttle but under load, when I pull trigger on gun, with fluctuates from high to low to high to low , etc.....
     

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