Johnson 50 VRO low idle and stalling

Discussion in 'Outboards' started by CDK, Jun 4, 2011.

  1. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Not my boat or engine but I'm trying to help out my son...

    Johnson 50 VRO from 1989, VRO pump disconnected, both carbs cleaned and parts replaced.

    Does everything an outboard should, except stable idling. I have played with the idle adjustment screws, but with optimal settings rpm is still below 700 rpm.
    From the looks of the throttle mechanism, ignition timing seems crucial but I found nothing useful on the internet.

    Does he really have to invest in a workshop manual for such a trivial matter.
     
  2. powerabout
    Joined: Nov 2007
    Posts: 2,931
    Likes: 66, Points: 48, Legacy Rep: 719
    Location: Melbourne/Singapore/Italy

    powerabout Senior Member

    just wind the timing up till you get your idle speed with the butterflys closed.
    They did have a setting with butterflys open and retarded timing to meet an emission rule.
    Make sure it is running warm enough
    I assume if you wind each idle screw in and out it will go from too lean to too rich?
    Are the vro oil ports at the pump capped?
     
  3. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Thanks Powerabout.
    The temp is 70C after a few minutes so the thermostat is working.
    With one of the idle screws turned in the engine stalls at once, current setting is each screw 1.5 turns out. Further out the rpm drops and it stalls.

    The VRO input is capped, cable removed.

    I will clean the plugs, adjust the ignition linkage and if nothing works out, order the bloody manual.
     
  4. pistnbroke
    Joined: Jan 2009
    Posts: 1,405
    Likes: 34, Points: 48, Legacy Rep: 404
    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    I have the manual..well a Clymer

    Have clymer 48-235 hp 73-90 Evinrude/Johnson and have looked through but did not see anything to help someone like yourself ..if you need specific information or scans of pages send me a pm with a proper e mail address ...
     
  5. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    Reed valves that don't close well will do that too. At high RPMs there is enough flow that a small leak does not matter.
     

  6. pistnbroke
    Joined: Jan 2009
    Posts: 1,405
    Likes: 34, Points: 48, Legacy Rep: 404
    Location: Noosa.Australia where god kissed the earth.

    pistnbroke I try

    Sent you 20 pages from the manual ..good luck
     
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