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Help! Briggs & Stratton problem

Discussion in 'Mechanic and Repair' started by CTdave, Dec 9, 2006.

  1. CTdave

    CTdave LawnSite Member
    Messages: 4

    Hello all. I'm wondering if anyone could give me a suggestion.
    I have an 18hp V-twin B&S on a John Deere. It is only 6 yrs. old but it sat for two years (yes, with fuel in it). I went to use it & had a surge/stalling problem. It would only run if I kept pushing the choke. The local JD dealer said the inside of the carb was probably pitted so I bought a new carb for $130. I installed it & the same problem existed. Then it dawned on me that the fuel in the tank was bad. I cleaned the tank, blew out the lines & replaced the filter. Same problem. Then I figured the bad fuel clogged up the new carb so I dropped the bowl, took out the jet (inside the bowl) and the jet with the long tube on top of the carb & blew everything out.
    SAME DAMN PROBLEM!! It will idle ok but when I run it up to 1/2 throttle or more, it dies if I don't hit the choke quickly while the rpm is dropping. The governor opens all the way when this is happening causing the stalling.
    Model 350777
    Type 1137-E1

    What do you think?
    Thanks for your time!
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Remove the fuel line from the carb. and hold it over a container then crank the engine over checking fuel flow, The diaphragm in the pump could be hard or gummed up and not pumping enough fuel to run higher RPMs. Does it continue to run at higher RPM's with the choke applied ?
  3. CTdave

    CTdave LawnSite Member
    Messages: 4

    restrorob, thanks for the quick reply.
    I was just outside working on it again. I have checked for fuel flow. I didn't check pressure but there is a nice flow, shooting out about an inch or two into a pan. I cleaned out the pump before I replaced the carb.
    I did find another clue! It idles fine after choking two or thee quick times (as it is dying). Once warm & at idle speed, I find that the second I try to advance the throttle (a little or alot), the governor (arm at the bottom of the engine) fully advances & pushes the rod up which operates an internal flap (same size as the choke flap) which is inside the carb. If I don't give the choke a quick shot, it dies out right away.
    I mis stated the problem when I said it was a "surge problem". It doesn't surge, it just dies out. The governore "surges" & kills it.

    The tractor was stored for roughly two years in my heated (50 degree) garage. It was running perfectly for three years before that. I have fresh fuel in it, new carb, new inline filter.

    Thanks again for your help!!
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Well Dave, It's possible after sitting all that time that some dried out carbon built-up on the piston and head popped loose when you tried to start it the first time. This carbon could have gotten under a valve keeping in from closing thus causing it to run on one cylinder.

    Loosen the plug wires where they can be removed easily then start it up at idle, With insulated pliers remove each plug wire one at a time and see if it stalls. If it does the opposite cylinder is not running and needs further checking.
  5. CTdave

    CTdave LawnSite Member
    Messages: 4

    Both cylinders firing properly
  6. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    take the carb off, tear it all the way down, spray it out with 3m brake cleaner, blow it out with 120 pounds of air, reassemble. then flush fuel tank,change fuel filter, start it up. the key here is completely remove all peices from carb - just don't leave a part installed and blow it out.
  7. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Hmmm, This engine is shown with and without a fuel cut-off solenoid on the float bowl, Does your's have this ? It also shows a Nikki or Walbro carb. which do you have ? Also, When you start it up where do you have the throttle control set at (Idle, Half, Full) ?

    It still sounds like a fuel delivery problem as khouse mentions, You may try as he said again.
  8. CTdave

    CTdave LawnSite Member
    Messages: 4

    GOT IT!!!!!!!!!!!!!
    After installing the new carb which the John Deere guys said I needed & getting the same symptom, I realized I still hap crappy gas in the tank. I cleaned the tank & just as you said, I cleaned out the carb two more times & then today, I finally disassembled it completely & SHAZAM!!!! it actually works! It seems that the smallest trace of junk in the trunk (tank) will screw the works.
    I had to clean out the carb four times (today) and it did the trick!
    Thanks to everyone for your thoughts!

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