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Old 10 August 2012, 16:27   #1
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Engine dies at WOT

Hi,

Went out yesterday and to start off with, I drove over some submerged netting and wrapped up and stalled the engine.

Managed to cut it free and thought id anchor up stop for some lunch.

When I came to set off agiain the engine was fine, but then when I went to WOT the engine would start like chugging and slowly the revs would drop and it would stall.

It would also stall if it accelerated hard. It works fine if I slowly accelerate to 3/4 throttle.

Im thinking its fuel related ? Any help would be great... Thanks
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Old 10 August 2012, 16:48   #2
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I had this on my e-Tec it turned.out to be the fuel tank pickup
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Old 10 August 2012, 17:03   #3
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Or the dreaded air vent on the top of the tank .. was it open ?
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Old 10 August 2012, 17:21   #4
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A dodgy primer bulb is another potential culprit
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Old 10 August 2012, 18:38   #5
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Could also be a dodgy diaphragm or blocked jet. Dirty fuel maybe.

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Old 11 August 2012, 04:03   #6
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Quote:
Originally Posted by Bigmuz7
Or the dreaded air vent on the top of the tank .. was it open ?
I'm guilty of this
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Old 11 August 2012, 07:30   #7
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Quote:
Originally Posted by Tom465 View Post
It would also stall if it accelerated hard. It works fine if I slowly accelerate to 3/4 throttle.

Im thinking its fuel related ? Any help would be great... Thanks
We had same problem a few weeks ago on our Suzuki DT75 - turned out to be the gear linkage squashing the fuel line in the engine housing (fuel line not in it's proper clips).
Only happened at WOT as this pushed the linkage just a little bit harder against the fuel line.
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Old 11 August 2012, 11:16   #8
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thanks for all the suggestions

Spent the morning following up all your comments.

  • Pick up pipe was good and unblocked
  • Yes the air vent was open
  • Bulb was working good
  • All fuel lines are fee and not cough up or blocked
  • Fuel Filter is clean
  • Plugs are also good.


My engine is a 30hp Yamaha auto lube.

I did use some old fuel the time before I went out. It was 200:1 oil mix so I thought it would be ok ?

This time I went out it was clean fresh fuel.

When it is idling it would now missfire and stall.
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Old 11 August 2012, 13:09   #9
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200:1 sounds pretty lean for a 2-stroke. What's your spec say -100:1? 50:1? Not enough oil is a recipe for disaster.

Dump the suspect fuel, fill with fresh (and correctly mixed) fuel, and see what happens.

If you suspect a fuel pump, try pumping the primer bulb while running. If it corrects the misfire, then it's definitely a fuel delivery problem. Fuel filter, fuel pump, or clogged line, most likely.

jky
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Old 11 August 2012, 13:37   #10
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Sounds like fuel but as the problem started when you got fanned up I would check your bush has not slipped further up the propshaft and your propeller is not eating your gearcase.
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