Yamaha 50 hp 2 stroke will not start...

Discussion in 'Outboard Maintenance' started by awelch1, May 7, 2014.

  1. awelch1

    awelch1 I Love microskiff.com!

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    Took my skiff out early in the morning on Monday. Motor cranked fine at the launch and ran perfectly (20 min) to fishing spot. Fished for approximately 3 1/2 hours with motor off and battery turned off. Motor cranked fine and made the run back to the landing. There were a couple of guys throwing castnets and "hanging out" on the dock. I decided to turn the motor off and pack up before trying to fool with them. When I went to start the motor again, it turned over fine, but would not crank. I had to get towed in. The motor has good compression, good spark, good battery. Any ideas on what the issue could be? Any help would be greatly appreciated.
     
  2. Brett

    Brett > PRO STAFF <

    Kill switch activated?
    Engine in gear? Will not start due to ignition lockout.
     

  3. awelch1

    awelch1 I Love microskiff.com!

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    Guilty of those, but unfortunately this time its not the case.
     
  4. DuckNut

    DuckNut Brandon, FL

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    Check your spark. If no spark, what Brett said.
     
  5. awelch1

    awelch1 I Love microskiff.com!

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    I checked the spark and it is good.
     
  6. Brett

    Brett > PRO STAFF <

    Fuel, air, coolant and spark at the proper time.
    Without those 4 components the outboard won't run.
    One of those is being interfered with.
    Process of elimination time.
     
  7. DuckNut

    DuckNut Brandon, FL

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    Disagree with you on this one Brett...Coolant is not a requirement to start, it is a requirement to continue to run though. ;)
     
  8. cutrunner

    cutrunner Cert. Yamaha technician

    Bam!!!!
     
  9. Brett

    Brett > PRO STAFF <

    Oh, playtime is it?

    That Bammm, cut, was that the sound of a cylinder jamming solid
    and the piston rod going through the side of the block due to lack of coolant? :-?

    And as you said y'erself, DN, the operative word is "run".

    and I
    Tee Hee, always fun engaging in a battle of wits.
    Seems to be a little one sided though... ;D ;)


    Back to the original problem now, need to go at it the same way a shop would.
    The outboard won't "run". Pop the cowling and look at the setup.
    Connect a portable fuel tank with new fuel/mix and different hose.
    When you pump the primer bulb can you hear fuel entering the carb?
    Does the bulb finally stop pumping and become solid, resisting your squeeze?
    No visible leaks anywhere? With the water/flush muffs on try and start the engine.
    If no luck, after cranking, pull the plugs and smell if fuel is present in the cyclinders.
    Check the plugs, are they clean and dry? Wet and greasy? Covered in black velvet?
    Each one indicates a symptom. Clean-dry means no fuel entering cyclinder.
    Wet greasy, smelling of gas, probably flooded, carb needs work.
    Black velvet and wet indicates running rich and with the carbon layer
    is shorting out the spark. While the plugs are out, do a compression test.
    Why? The plugs are out and it's a good way to keep an eye on things.
    Do a spark gap test on each plug wire to verify the voltage is high enough.
    Install new plugs, do a timing check to verify brain box is working.
    If spark was ok, then fuel system is probably the problem. Check fuel pump.
    check last chance filter, if fuel is in float bowl and not making it to the cylinders
    then the carb is clogged or there's an air leak on the intake side of the block.
    If the engine was flooded, then the float isn't functioning and carb should be rebuilt.
    It's all about fuel, spark, air and coolant.
     
  10. DuckNut

    DuckNut Brandon, FL

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    And as you said y'erself, DN, the operative word is "continue".

    Fixed it for you - but what I really accomplished is that you typed 274 words to help this guy out.
     
  11. Brett

    Brett > PRO STAFF <

    True, it's a character defect. :-[

    But now that it's typed, we can all "previous post" it.  ;)

    btw, y'er ocd is showin'. Ya' actually counted 'em? ;D
     
  12. awelch1

    awelch1 I Love microskiff.com!

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    I really appreciate all your help guys. I was hoping this would be a "classic" problem with an easy fix.

    Portable fuel tank:
    Connected tank with new fuel
    Sounds like fuel enters carb
    Bulb becomes solid
    No leaks

    Tried to crank - No luck

    When I pulled the plugs - Smell of gas - slightly wet and greasy. I will try and upload a picture when I find the cord for the camera.

    Compression: ~107 w/ 2-3 psi variance at each

    Spark gap and spark: good & good

    Seems to me that it is looking like a fuel pump (new) or carb problem. The only thing that makes me think otherwise is that it was working one second and not working the next.
     
  13. Creek Runner

    Creek Runner Well-Known Member

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    I really try not to comment on tech threads anymore, but just because I want to mess with Brett.

    ^ Will not allow the engine to turn over at all, so yes technically it won't start because it wont turn over. But if the engine turns over it's not the neutral safety switch. :p

    I also will agree coolant is not a required item. :-X :D

    To the op perform a Fuel Pump test, if not then its carbs if you have compression and Spark. Although I find it weird it was running fine, you shut it off, and then wouldn't start back up and it's the carbs. Even if the carbs were clogged I would think it would pop off and then die. But if it has Compression and Spark then all signs point to fuel.
     
  14. Brett

    Brett > PRO STAFF <

    No worries Creek, mess all ya' want.
    I'm a big boy and can take the heat.  ::)

    When I hear symptoms, I go for the obvious solutions first.
    Why? Because those are moments of personal foolishness that immediately come to mind.  :-[  ;D

    Coolant not a required item?
    Blasphemy coming from a service tech....wait, I see what you did.
    Y'er looking to create more repair business, ain't ya'?  :-? ;)

    Are we having fun yet? :D
     
  15. DuckNut

    DuckNut Brandon, FL

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    Try a shot of starting fluid. If it pops you have spark at the right time. If it dies then you have identified the problem - fuel delivery.
     
  16. awelch1

    awelch1 I Love microskiff.com!

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    Thanks again guys. Will hopefully have it identified better today.
    Everyone who I have told about my situation ask if the skiff was in gear and if the kill switch was in. One guy told me a story about his friend that had spent his entire life on the water. One evening he tried to crank up his boat to head back in with no luck. The mosquitos were terrible that night and he had to resort to rubbing gas on his clothes to keep them away. When DNR got to him the next morning he showed them that his boat would not crank. The DNR officer said "why dont you try picking your kill switch up off the floor and giving it a try".
     
  17. awelch1

    awelch1 I Love microskiff.com!

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    UPDATE

    I believe I have narrowed the problem down to fuel delivery. When I switch the emergency enrichment lever to “open”, the motor fires right up. When I switch it back to “normal”, it runs for 10 seconds and dies. It will crank for a couple seconds in “normal”, but will not run. Seems like this points to a problem with a carbs. Is there any other or more obvious problem I am missing? Thanks again guys.
     
  18. ronyates90

    ronyates90 I Love microskiff.com!

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    check your kill switch (located on control box
     
  19. awelch1

    awelch1 I Love microskiff.com!

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    Just an update

    Pulled and cleaned the carbs today. The motor will now crank and run for a while, but eventually cuts out when left idling. When I bump the throttle into gear, the motor will continue to run. I am going to pull the carbs again and rebuild with a kit. I appreciate all y’alls advice in helping me diagnose. It was just so strange that the carbs would cause the motor to not start so suddenly.
    Do you think it would be worth it to go further after the rebuild – cleaning fuel lines, draining tank, etc?