High stress Tohatsu 6hp 4 stroke.

[lumphammer]

Twice now manoeuvring to get into the lock gates my 2 year old outboard (just recently serviced) has cut out as I go into slow ahead. The first time was after 4 hours of steady motoring with no problems. The second time was locking out with about 20 minutes warm up. During the warm up it wouldn't settle on a constant speed with the throttle at just above idle, one moment it would starting revving up then slow down so much I thought it was going to stall, eventually after about 10 minutes it settled on a steady rpm. This was with choke in. Then as we approached the lock gates, it got very close to stalling so I had to rev up to keep the engine going. Very stressful for me, even more so for the very expensive yacht I was sharing the lock with.
Thinking of possible causes - idle speed too low? Carburettor needs cleaning (I don't think that was done at last service)? Any other areas to look at?

 

[Fantasie 19]

I would take it back to whoever serviced it.. but I'm a mechanical numpty..

 

[KevinV]

Sounds like a blocked low speed jet to me - has it been left sat with fuel in it?

 

[rotrax]

Many modern low emission four stroke outboards have the idle jet set in the factory to pass the requirements of the test. The adjustment screw is covered by a blanking plug.

On our 5HP Suzuki I removed the plug and adjusted the idle screw properly.

It starts and runs SO much better now.

Give it a try, or have the service guy do it.

 

[Boathook]

I would think something to do with the float in the carb sticking.

If it was 'dealer' serviced I would take it back to them.

I was told by the dealer who sold me my honda to use E5 petrol plus an enzyme additive. When I know I won't be using the engine for a while, such as after a holiday, I disconnect the fuel line at the engine and run the engine until it stops to empty the carbs as much as possible.