Mariner outboard cuts off...

[dimwolf]

Hello!

I've got a Mariner 4 2-stroke outboard that starts OK but after running for several minutes it slows down, doesn’t respond to throttle opening and finally stops. After that is refuses to start again. I've taken the carb apart but found nothing suspicious - it looks nice and clean. What else can cause this misbehaviour?

Possibly anybody can advice an outboard specialist in Edinburgh area?


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[jimi]

Have you 1) opened the ventilator 2)switched the petrol on ?

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[tugboat]

The obvious cause would be that the fuel tank is getting vacuum locked, due to the breather on the filler cap being either closed or blocked. Simple to test- when the engine stops remove the filler cap, if there is a rush of air into the tank- Bob's your uncle. Other possibilities- blocked fuel filter in the line or the diaphragm in the fuel pump is split.

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[dimwolf]

Yes and yes. There was plenty of fuel in the carb when I've taken it off...

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[jimi]

Choke on causing carb to flood?

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[Jools_of_Top_Cat]

Are you getting water pouring out of the tell tail.

Is there a smell of hot metal and paint just as it starts to fail?

<hr width=100% size=1>Julian

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[nickjaxe]

Have you checked for a spark at the plug.

Nick.

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[dimwolf]

Water is running. I didn't check the spark but if there were no spark it wouldn't start at all, would it?
What worth double checking is ventilator, thank you tugboat! I'm sure it was open but I didn't check it for blockage.


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[steve28]

dump the fuel and try some new stuff in case there is water in it.



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[Superflid]

I've had similar symptoms from failing ignition coils. OK when cold, fail when hot.

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[ArthurWood]

Had a similar problem with a 3.3: was water in carb bowl. Open drain plug in carb bowl and see if any water comes out.

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[nickjaxe]

The reason I said check the spark is as superflid said, you can have a coil go down when they get hot, I had this prob on a 4hp penta, when it stopped left it 15mins it would then run ok for about 15mins, but you need to check for a spark as soon as it cuts out.

Nick.

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[dwarwick]

had this problem with evinrude 4hp twin. Apparent cause was old fibre washer bits blocking carb jets. Carb jets and drillings are so small it takes bugger all to block them. Replace with rubber or new fibre. Worked for me.


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