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  1. #1

    Default Evinrude 50 hp stalls at idle

    Have a 1987 Evinrude 50 hp whith good compression and runs well at high speed, but will not run at idle unless I push the electric choke all the time. Does it not get enough fuel? Any idea where to begin? The carbs have been rebuilt two times.

  2. #2
    Join Date
    Nov 2005
    Location
    Mt. Zion, Illinois,
    Posts
    883

    Default Re: Evinrude 50 hp stalls at idle

    Is the VRO still in use or has it been converted to premix?

    Check all fuel line connections and make sure they are snug with no air leaks. You might also check your primer bulb and make sure the check valve is functioning properly. If the valve is bad it can allow the fuel to drain back to the tank. It's possible the fuel lines aren't staying primed under low speed operation and causing your problem.

  3. #3

    Default Re: Evinrude 50 hp stalls at idle

    It is converted to premix long time ago.
    I tried also to squeeze the bulb with the motor running without luck. Can it still be a faulty check valve then?

  4. #4
    Join Date
    Sep 2010
    Location
    ontario
    Posts
    16,014

    Default Re: Evinrude 50 hp stalls at idle

    Good compression would be 140 PSI on that motor.-----What is yours ?-----Pushing in the key opens a valve that puts fuel into the motor.---This fuel bypasses the carburetors.-----That stronhly suggests that you have an issue with fuel from carburetors !!

  5. #5
    Join Date
    Dec 2012
    Location
    newport news, va
    Posts
    184

    Default Re: Evinrude 50 hp stalls at idle

    the idle circuit in the carb. may need cleaning, the core plug (small silver disk) on top of carb is removed and a couple of very small holes under it should be cleaned.
    also what are the compression numbers?

  6. #6
    Join Date
    Feb 2001
    Location
    Central West Florida
    Posts
    14,817

    Default Re: Evinrude 50 hp stalls at idle

    The engine running normally at high speed indicates that the high speed jets are clean and no problem exists there, and fuel must flow thru that jet before it can gain access to any other fuel passageway... BUT the proper amount of fuel is not flowing thru the idle passageways.

    Is the engine actually hitting its top rpms as in the past with speed as normal... or has that dropped off?

    Check that very small brass tube that is located off center within the larger high speed nozzle... It leads from the bottom of the float chamber up to the main slow speed passageway... clean it with a piece of a fine single strand steel wire as solvent and even pressurized air won't do that job properly. They clog easily!

    For reference, with all s/plugs removed... what is the compression psi reading of each individual cylinder?

    Also... with the s/plugs still removed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?

    Do Not reply with generalities such as "The compression is okay"... "The spark is great"... that sort of thing as that really tells us nothing.
    We occasionally have questions. If you fail to answer, it may affect ours.

  7. #7
    Join Date
    Jun 2013
    Location
    Duluth Mn
    Posts
    1,291

    Default Re: Evinrude 50 hp stalls at idle

    Good advice Mr. Joe, also Scalhoun. Kevin and Racer. Since it keeps running while cycling the primer/choke, it is unlikely anything but an internal carb problem...... low-speed circuit. I could be wrong, but that's nothing new. Clean, as Joe, Racer, and Scalhoun said, with a physical tool like a welding tip cleaner. Spray cleaner and air might open up a passage but it has to be opened to the correct size, or it will starve out. This can cause a lean running condition and score pistons, etc.

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