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Old 14 August 2015, 16:33   #1
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yamaha 50 stalls under load

Hi wonder if anyone has any pointers for me to try before it goes off to be repaired.

Engine is a late yamaha 50hp 2 stroke now with tiller fitted, the engine ran well today on the boat with new fuel in the tank.

When in the water later it idled fine in neutral, but once in gear would only go at say 1/4 power at full throttle. Later on though as soon as you put it into gear it stalled and would not run. In neutral though it still runs perfectly with no load?

Anyone have any experience/ ideas please?
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Old 14 August 2015, 17:37   #2
cam
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My Yamaha 50 (4 Stroke High Thrust Edition) also did this (last used about 9 months ago due to exams etc) It has since been dramatically serviced but if you get any ideas I would also like to know

I found that trimming helps this but since its a tiller I cant help, sorry
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Old 15 August 2015, 00:54   #3
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No problem Cam
Ill put up any results I find
Like you this hasnt been used for a bit. Im thinking it could still be fuel related or some crud in the carbs. Although ive had that before and it didnt behave like this
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Old 15 August 2015, 03:33   #4
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Just a thought, sounds like idle jet is clear but main jet clogged?
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Old 15 August 2015, 04:08   #5
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Check the fuel pump. Could be a worn diaphragm. While you're there check the fuel pipe connections that the 'o' ring seals are intact and not dislodged, and the primer bulb goes hard, etc. You can drain the carbs at the fuel bowl to look for contaminants before progressing to full carb strip down.
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Old 15 August 2015, 16:11   #6
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Appreciated guys

Thanks ill look into those things before I admit defeat and take it to the pro's

Strangely tried it again this evening and will now run in gear but still only about 1/4 throttle when its flat out, but will no longer stall in gear. In neutral its still the same as before perfect. Its pumping water really well and sounds nice, just wont open up still/ hasnt got the power.
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Old 15 August 2015, 17:14   #7
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Water in carbs?
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Old 16 August 2015, 00:49   #8
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Not ruling anything out yet, although wouldnt have thought it was water as has been running a couple of hours with new fuel so a fair bit has gone through.
Like I said though not ruling anything out as of yet so cheers though
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Old 27 August 2015, 21:00   #9
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As stated above Fuel Pump, High Speed Jet.
Perhaps Clogged fuel filter,fuel tank not venting enough. All in all fuel starvation or a bad secondary plug high tension wire, coil, bad plug... Good luck.
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Old 28 August 2015, 04:13   #10
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Quote:
Originally Posted by Nightfisher View Post
As stated above Fuel Pump, High Speed Jet.
Perhaps Clogged fuel filter,fuel tank not venting enough. All in all fuel starvation or a bad secondary plug high tension wire, coil, bad plug... Good luck.
Hi

Check plugs after runing make sure there not wet.
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Old 28 August 2015, 10:05   #11
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Pumping the primer bulb while increasing RPM should tell you if it's a fuel draw issue. Won't tell you if things are clogged (at least not definitively) though.

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Old 28 August 2015, 12:09   #12
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Oil injection model ??
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Old 29 August 2015, 04:03   #13
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I had exactly the same problem this week with my yamaha 70 2 stroke tiller. Check the carbs, take out all the jets and clean them. Use carb cleaner/airline through them and a thin wire if you can find one (from a wire brush etc) to put through the holes in the jets
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Old 21 September 2015, 15:50   #14
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Just as an update turned out to be slight water/ crud in the centre carb, as soon as it was cleaned out it ran beautifully again. So back to 100% now.
Thanks for the help Guys
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