10 HP Briggs and Stratton, only runs on CHOKE. Whassup?

Discussion in 'Non-Ford Engines' started by scooper77515, Jun 23, 2012.

  1. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    Every 6 months or so, I fire up my portable generator. This time, it started right up but won't run once I take it off choke. It will run on half choke, but if I back it off a little it starts to starve and will sputter out on me. Runs smoothly with choke on, with or without air filter (it is clean and new).

    My brother-in-law's machine is doing the same thing this season :huh:

    Any ideas, hints, or solutions?

    The machine is pretty much brand new. I have had it three years, run it maybe 10 or 12 hours. Fuel has been mixed with Stabil, and I swap it out every two years if I don't use it.

    Not getting enough fuel?
  2. MaverickDan

    MaverickDan I wanna go fast!!!

    Joined:
    Jan 1, 2007
    Messages:
    648
    Media Gallery:
    3
    Albums:
    1
    Likes Received:
    4
    Trophy Points:
    67
    Location:
    Midlothian, VA.
    Vehicle:
    73 Maverick 4dr
    Sounds like the main jets are clogged. If it has a fuel shutoff next time you use it set it to off and let it run out of fuel, helps keep the carb clean.
  3. Jsarnold

    Jsarnold Senior Member

    Joined:
    Oct 29, 2008
    Messages:
    2,846
    Media Gallery:
    13
    Albums:
    1
    Likes Received:
    0
    Trophy Points:
    100
    Location:
    Raleigh, North Carolina
    Vehicle:
    '72 Sprint
    Do you close the fuel line valve and run the fuel out of the carb after each use? If not, the carb is probably gummed up and not feeding fuel except on choke.
  4. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    Yes, I always run it dry, then choke it to continue running until it is completely dry. I just drained and cleaned the tank, and replaced the fuel filter/petcock assembly, and the old filter and lines look fine.

    I will put it all back together and fill it with fresh fuel and squirt some seafoam aerosol into it and give it a "carb cleaning" and see if that helps.
  5. Dave B

    Dave B I like Mavericks! Supporting Member

    Joined:
    Mar 9, 2002
    Messages:
    16,724
    Media Gallery:
    34
    Albums:
    1
    Likes Received:
    51
    Trophy Points:
    307
    Location:
    London, Ontario
    Vehicle:
    3 Grabbers
    Take the float bowl off the bottom of the carb, and see if there is a small hole drilled in the bolt that holds it on, make sure it's clean. The engine on my snowblower does that from time to time, I use stabilizer, and always run it dry in the spring.
  6. Jsarnold

    Jsarnold Senior Member

    Joined:
    Oct 29, 2008
    Messages:
    2,846
    Media Gallery:
    13
    Albums:
    1
    Likes Received:
    0
    Trophy Points:
    100
    Location:
    Raleigh, North Carolina
    Vehicle:
    '72 Sprint
    Hope the carb cleaning and fresh fuel does it for you. Guess I should get mine out and see if it will start. :yup:
  7. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    It seemed to help a little, but didn't fix it. Wasn't worth the $12 bucks for the bottle of Seafoam. Once again, I am not impressed with the stuff.

    So, when the engine cools down, the carb is coming off for a rebuild, or at least a cleaning.
  8. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    OK, tore the carb down, there was just a couple pieces of crud in the bowl, and the infamous varnish smell. Cleaned it all up, reassembled, and no difference. Still runs fine one or two clicks off CHOKE, but when I flip it any further toward RUN it falls on it's face and dies.

    Runs pretty good and putting out 123V with it on semi-choke. Should I just use it like that or am I missing something?
  9. MaverickDan

    MaverickDan I wanna go fast!!!

    Joined:
    Jan 1, 2007
    Messages:
    648
    Media Gallery:
    3
    Albums:
    1
    Likes Received:
    4
    Trophy Points:
    67
    Location:
    Midlothian, VA.
    Vehicle:
    73 Maverick 4dr
    Running it on choke at all times will use a lot of fuel and could wash out the cylinders. Did you blow through the passages with compressed air?
  10. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    Yep. First with carb cleaner, then with compressed air, hit one spot with a q-tip in the throttle body where there was a little brown stain, and slapped it all back together.

    No go.
  11. Jsarnold

    Jsarnold Senior Member

    Joined:
    Oct 29, 2008
    Messages:
    2,846
    Media Gallery:
    13
    Albums:
    1
    Likes Received:
    0
    Trophy Points:
    100
    Location:
    Raleigh, North Carolina
    Vehicle:
    '72 Sprint
    Or aerosol carb cleaner? I might run it for a while on partial choke with a small amount of gas and some injector cleaner mixed in. If that didn't do it, I'd disassemble the carb, soak it for a couple of days in carb cleaner, and blow passages out with aerosol. If it didn't run off choke after that I'd admit defeat and buy a replacement carb.:cry:
  12. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    A good bit of the carb's innards are plastic, I doubt it would hold up to carb cleaner soak. Besides, it was amazingly clean, before, and more so after I cleaned it. Shouldn't be running this bad.

    Anyone have any idea what that spring and rod that control the automatic rpm adjustment go to? There is a second butterfly inside the carb just prior to the intake that is apparently controlled by vacuum, and is the actual throttle controlling the rpm. the spring and rod attach to the butterfly, then go somewhere behind some engine cover. What is at the other end of those?
  13. RASelkirk

    RASelkirk Retired! Supporting Member

    Joined:
    Jan 10, 2008
    Messages:
    1,189
    Media Gallery:
    40
    Albums:
    1
    Likes Received:
    4
    Trophy Points:
    122
    Location:
    Port Neches, TX
    Vehicle:
    Sonic Blue '72 w/LS-1, 200R4, 9" w/3.50
    Goes to a governor inside the flywheel that controls max RPM's, don't think there's any vacuum control on these motors...
  14. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    Well, it looks like i need to tear the carb down again. Internet searches told me that the long brass tube with lots of holes in it needs to have EACH hole individually reamed out with a piece of monofiliment or similar non-metal probe. There is apparently a small piece of gunk in there somewhere.

    It is hot, over 100 today. But we have a hurricane heading our direction, so I guess I better get on it hot or otherwise.
  15. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    "Fixed" it???

    I tore into the carb and all looked clean. But there was a spring in the float bowl that had moved before I could get the assembly back together. So I put it where it belonged, and now it runs in RUN but it wouldn't hold a steady idle. It kept bouncing up and down with that rod that controls the inner butterfly. I pulled the cover off and found a semi-elaborate array of springs, rods, and levers and you can move the springs into various holes to change adjustment, but I figured I would just bypass the entire self-adjusting idle mechanism.

    I wire tied the lever that had the rod on it, and set the idle adjustment screw at the other end so the inner butterfly stays at one place and is fixed.

    I checked the voltage and it was low, around 112, so I adjusted that screw until it came up to 120 +/- .2 volts (it still bounced a little).

    So, my question is this...when I put a load on it, my fixed butterfly will prevent it from opening up more, will this make me have a lower voltage as I put more load on it? Or is the torque on this thing enough to just pull it right at 120 volts despite the load (as long as it is appropriate to the motor, 5500 or whatever)?
  16. Dave B

    Dave B I like Mavericks! Supporting Member

    Joined:
    Mar 9, 2002
    Messages:
    16,724
    Media Gallery:
    34
    Albums:
    1
    Likes Received:
    51
    Trophy Points:
    307
    Location:
    London, Ontario
    Vehicle:
    3 Grabbers
    Is this like yours?
    [nomedia="http://www.youtube.com/watch?v=O-fROtibEvE"]Briggs and Stratton 10hp Generator Carburetor Repair - YouTube[/nomedia]
  17. Jsarnold

    Jsarnold Senior Member

    Joined:
    Oct 29, 2008
    Messages:
    2,846
    Media Gallery:
    13
    Albums:
    1
    Likes Received:
    0
    Trophy Points:
    100
    Location:
    Raleigh, North Carolina
    Vehicle:
    '72 Sprint
    I think the engine speed is important to maintain 60 cycle AC power. Wouldn't disable the governor.
  18. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    Yep, same carb (different model generator). That jet is fine on mine. Everything looks fine, now.

    But won't hold steady idle with that governor bouncing around.

    It runs with the choke off, now.
  19. scooper77515

    scooper77515 Accepting Hand-me-downs Supporting Member

    Joined:
    Jun 30, 2004
    Messages:
    14,335
    Media Gallery:
    19
    Albums:
    1
    Likes Received:
    7
    Trophy Points:
    192
    Location:
    Dayton, TX
    Vehicle:
    74 Mav 5.0 +.040 & C4
    Had to disable it or figure out how to adjust it correctly. Otherwise, it wouldn't hold a steady rpm and was bouncing 120 volts +/- 15 or 20 whole volts. Now it stays right within half a volt of 120.
  20. Jsarnold

    Jsarnold Senior Member

    Joined:
    Oct 29, 2008
    Messages:
    2,846
    Media Gallery:
    13
    Albums:
    1
    Likes Received:
    0
    Trophy Points:
    100
    Location:
    Raleigh, North Carolina
    Vehicle:
    '72 Sprint
    Right. Just sayin', when you're using the generator I think it will be important to have the governor working too. Otherwise, the engine RPMs will change too much with electrical load and it won't maintain 60 cycles. Some equipment, e.g., resistance heating or lights, wouldn't mind if cycles are off buy I expect some equipment might not work so well its not putting out pretty close to 60 cycles.

    Not pretending to be an expert here, just something I'd be concerned about. Think you need to get rid of the surge with the governor enabled.

Share This Page