promotion image of download ymail app
Promoted
Anonymous
Anonymous asked in Cars & TransportationMaintenance & Repairs · 2 months ago

Help diagnosing 3.5 horsepower engine problem?

I’ve been fixing and flipping lawn equipment, and this lawn-mower has stumped me! The engine has compression, and it also has spark. So far I have oiled up the fly wheel, re-spaced the ignition coil, and cleaned / tuned the carb. Starter fluid helps it turn over once or twice, but it’ll die right after. Any advice would really help, thanks!

11 Answers

Relevance
  • M.
    Lv 7
    2 months ago
    Favorite Answer

    It sounds like a fuel starvation issue.

    Passageways in carburetor need to be blown out with compressed air.

    Sometimes a fuel strainer inside the fuel tank is plugged with grass debris or other dirt.  Blow it out opposite from fuel flow direction.  Clean fuel tank with hot water and liquid dish soap.  Dry it gently with a hair dryer.

    Is your carburetor metal or plastic?

    Does it have a needle/ seat and float, or a diaphragm?

    Space the magneto coil with a business card.

    • Commenter avatarLogin to reply the answers
  • 2 months ago

    When it kills check for spark right away to make sure it has spark. 90% f the time the reason for this is that the main jet in the carb gets plugged up with old ethanol gasoline after sitting fr months.

    The other problem that happens is that the o-ring for the float needle swells up and won't let gasoline into the carb bowl. I've taken the carb bowl off and after cleaning out the main jet I take a small drill bit and ream out the o-ring by hand with the drill bit. That works if you can't replace the o-ring. You may have to reset the float level after reaming the o-ring if the gas doesn't shut off and floods the motor. You can see the gas leaking if you turn the choke of and open the throttle to look for gas running into the intake.

    Source(s): Mitsubishi Master Tech
    • Commenter avatarLogin to reply the answers
  • 2 months ago

    type of engine ..2 or 4 stroke?

    • Commenter avatarLogin to reply the answers
  • I'd love to know how you've 'tuned the carb' on an engine that isn't running.  If it fires only with starter fluid, then it isn't getting a proper amount of gas and air from the carb.  And since when do flywheels require oiling?

    • ...Show all comments
    • Actually, coils do have to be set at a slight gap between the pickup and the flywheel.  Newer coils are solid state, but older engines have a set of points under the flywheel that need a proper gap, but they rarely need readjusting.

    • Commenter avatarLogin to reply the answers
  • How do you think about the answers? You can sign in to vote the answer.
  • Dan
    Lv 5
    2 months ago

    Put a new spark plug in it, it's super cheap and a hard to see crack in it can cause this problem. Pull the bowl off the carb and clean it out with alcohol, same with the gas tank.

    • Commenter avatarLogin to reply the answers
  • 2 months ago

    Clean out the carburetor. They get gummed up after a period of storage and the best thing to do is blast some carb cleaner into the throat of the carb (remove the air filter) and give it a few tugs. I always add some STP to my gas can when I fill it since it helps a little bit while my mower is idle for about five or six month. I always add a little extra STP or Gumout directly to the gas tank the last mow of the season.

    • Commenter avatarLogin to reply the answers
  • Anonymous
    2 months ago

    Put another carb in it.  When cleaning does not fix it, you replace.

    • Commenter avatarLogin to reply the answers
  • 2 months ago

    Check for flooding. Check for vacuum leak.

    • Ben2 months agoReport

      Thanks for the suggestions, I’ll check those out

    • Commenter avatarLogin to reply the answers
  • Anonymous
    2 months ago

    Have you replaced the gas with fresh fuel? Have you got gas in the fuel bowl?  Do you see gasoline entering the throat of the carburetor?  Sounds like a fuel issue to me.

    • Ben2 months agoReport

      I did put new gasoline in the tank, and there was gasoline in the float bowl when I was cleaning it. It is likely a fuel problem, but I’m not quite sure how to diagnose it

    • Commenter avatarLogin to reply the answers
  • 2 months ago

    i would get a mechanic to check it out

    • Commenter avatarLogin to reply the answers
Still have questions? Get your answers by asking now.