25hp 1999 johnson popping and phutting

Discussion in 'Outboards' started by valvebounce, Jun 18, 2020.

  1. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    New fuel pump fitted,seems ok.
    I had the carb off,cleaned and used carb cleaner,set the float,seems ok.
    It starts first pull,ticks over nicely,but when I go for more revs,it stutters,coughs,and then stalls.
    Could I have upset the mixture,or the dialling in?
    There's not a lot of hours on the engine.
    Can the manual primer be blocked off from the carb?It's manual not the solenoid type.(could it be that)
    It works, I can see fuel being injected in when I prime it.
    The engine will reach high revs,but it splutters and cuts out.
    It was doing similar,but not as bad before I worked on it and changed the fuel pump.
    The engine number is--J25 RLEEB. The spark plugs are new.
    Any advice will be gratefully received.
     
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Firstly, have someone gently pumping the primer bulb, as you throttle up, and keep doing it, to see if the problem arises, if it doesn't, the problem is certainly in the fuel delivery, but there are a few stops along that tram line. You may even be sucking air through a connection along that line.
     
  3. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Gooday Mr E,
    So,if pumping the bulb cures it,are you saying it's between the fuel tank and the carb where the problem lies?
    I got the carb and primer unit diagram up for this engine,There is a 'T' piece missing between the primer and the carb.
    The motor was acting up slightly when I bought it,I thought it was just in need of a carb clean,seems like I was wrong.
    The primer fuel pipe has been run a different way to the diagram,because of the missing 'T' piece.
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Should be, if keeping the bulb squeezed cures the issue. Obviously you need someone else in the boat to conduct such a test. A sticking needle valve is a possibility, but squeezing the bulb should free that too.
     
  5. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    Did you pull the main jets and soak overnite in carb cleaner? The air blast the carb next day?

    The carb bowl is theoretically full. When you rev it up, the throttle opens and inserts more air into the system. That air combines with more fuel. If there is not enough fuel, the system gets too much air and leans out.

    Did you find a screen?

    It sounds to me like your carb cleaning was lacking.
     
  6. fallguy
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    fallguy Senior Member

    Also, is this tank testing or running on earmuffs?

    You can't rev all the way up on muffs or you are overrevving.
     
  7. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    It's only on muffs,I'm 50 miles from the nearest water.I have obtained a large drum to test it in for next time.
    I stripped the carb and left it submerged in kero overnight,then used carb cleaner,I used the carb cleaner to blow the jets through after a couple of hours.
    There is a new fuel pump on it with a filter screen,and a new clear inline filter.
    I'll adjust the mixture screw and see if it makes a difference,the starting point is two and a half turns out from fully in apparently.
    If I don't get a result,I'll start from square one with the carb cleaning.
     
  8. Mr Efficiency
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    Mr Efficiency Senior Member

    If all else fails, there is always the axe to employ. By and large, second hand outboards are closely related to that other problematic piece of machinery, the second-hand lawnmower. Where I live, that has given rise to the expression, "playing up like a second-hand lawn-mower", to describe people with erratic, obnoxious, and perhaps immoral behaviors. :rolleyes:
     
  9. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    At £600 I won't be going near it with an axe,Haha.
    When I was in your country,they used the expression 'Galahs' (if that's how you spell it)
    Biker boys and girls were--Bodgies and widges.
    Money was--Dinahs trays and zacks.
    Do they still serve beer in the boozers with a pistol on a pipe?
    I still miss that 'Victoria Bitter' and the 'Counter lunches'
     
  10. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    Yes, the ubiquitous galah, I don't think I've been to a place in Australia where there are none. Apparently their antics look a bit silly, to many people, so the name was then applied to people who behaved stupidly ! One bloke I knew was very reluctant to wear the company uniform, of a pink shirt and grey pants, complaining bitterly it made him "look like a Galah." :rolleyes:

    Galah.jpg
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    If you are a long way from the water, to be able to test run your engine under load, one option is to fit a "work wheel" to the engine, and run it with the leg in a tank, that puts a bit of load on the engine, you can't get running it on the muffs. It's just a part that replaces the propeller.
     
  12. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    blowing the carb with air doesnt cut it.
    you need to use a squeeze bottle with liquid, hobby shops have them for model engines.
    Then you can see that there is flow where its meant to be like the transition holes under the welsh plug on top of the carb it you havnt removed that and fitted a new one.
     
  13. Mr Efficiency
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    Mr Efficiency Senior Member

    As always, having a good workshop manual is essential, just work your way through the trouble-shooting procedures.
     

  14. valvebounce
    Joined: Dec 2010
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    valvebounce Senior Member

    Had look at it earlier,the clear inline filter had completely emptied,I had put a joint in the fuel line between the engine inlet and the fuel pump.
    I've ordered a new length of fuel pipe.I think the mixture screw should be set at 1-1/2 turns out to start with,not 2-1/2 like I thought it was.
    I see you're from Melbourne,I lived in Cheltenham many moons ago.I worked for GMH as and experimental toolmaker apprentice on Salmon st ,in Port Melbourne.
     
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