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Old 30 August 2016, 14:00   #1
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Stalling tohatsu 50hp

Currently sat on the boat after about the 5th test trying to find out why the boat keeps bogging down and stalling!

So the carbs have been stripped and cleaned after each test and mixtures reset.

Have put completely fresh fuel and oil in.
Cleaned all fuel lines.
Has a new fuel tank and line and inline filter.
New spark plugs.

The engine runs sweet on muffs and at low speeds. Then will go at full speed for around 1 minute then revs will drop and it'll stall.

Couple of pulls with choke on and it starts at straight away!

It will sometimes not gain revs again until you fiddle with the choke abit.

Doesn't miss fire at all just cuts out which suggests fuel but have done everything to do with the fuel system!

Loosing patience!!! Help please!!

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Old 30 August 2016, 14:03   #2
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Checked the Fuel Pump? Was causing similar issues on my Yam some time back
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Old 30 August 2016, 14:45   #3
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Ours had the same symptoms - fuel pump diagram kit sorted it.

If pumping the fuel primer when under load stops the bogging down it's probably the fuel pump.
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Old 30 August 2016, 14:56   #4
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Fuel pump same symptoms as I had with a Suzuki 25 two stroke
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Old 30 August 2016, 14:59   #5
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try pumping the primer when it starts playing up this should tell you if its the fuel pump
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Old 30 August 2016, 15:04   #6
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Quote:
Originally Posted by breezeblock View Post
try pumping the primer when it starts playing up this should tell you if its the fuel pump
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Old 30 August 2016, 15:16   #7
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You can rebuild the fuel pump with a genuine Tohatsu diaphragm fuel pump kit. Won't do any harm to replace.

I'd also check the female fuel pipe connection end. The pattern parts (if not genuine Tohatsu) are notoriously poor, so it could be a dislodged rubber 'o' ring restricting fuel flow. Check the connection locates properly on the engine and locks in position.

If it's a new fuel tank with primer bulb - then you can rule that out. Couple of years ago I was struggling to pump fuel as the rubber primer bulb was stiff. The bulbs deteriorate over time or the diaphragm fails. Quicksilver replacements are very good.

Lastly, strip off the airbox cover and check the butterfly choke valve. They are prone to seizing, so it's possibly not fully opening.
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Old 30 August 2016, 15:28   #8
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Cheers guys!

Off the water now.

Have replaced the fuel pump gasket and all looked good inside the other day but will follow your advice and buy a rebuild kit and go for another test!

Applying Choke did seem to make a difference.

If that still doesn't work I'll get all the carbs balanced and have it compression tested.

Cheers for the help! I'll keep you updated
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Old 06 September 2016, 04:17   #9
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Have you tried it since? Sounds like it's drawing air somewhere. Hopefully something easy like the fuel pump, otherwise could be the base gasket
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Old 12 September 2016, 16:03   #10
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Still waiting for parts at the moment!

No UK stock so 2 weeks for one from tohastu to arrive!
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