Yamaha 9.9hp 4 stroke 2002 WOT engine problem

[Svanosossie]

Hello,

My name is Svanossie, I am from Holland (europe)

I have a problem with a 9.9 Yamaha 4 stroke 2002 model.

Let me explain what the problem is.

When i rev the engine at half speed or more (when warm). It runs good but dies after a minute or 2.

Before it dies, it almost looks like it has no ignition suddenly and shakes twice (hickup) and then dies completely.

I also have a 15hp same model, and that one is oke.

The things I have checked and switched from the 15 hp model is.

-Fuel pump

-ECU unit

-Ignition coil

-Spark plugs

-Carberator cleaned

And I also disconnected the oil pressure sensor, all of this seems no difference or wat so ever.

After a couple of test runs I had take the (new) sparkplugs out and they are
white coloured at the ground electrode.

The carburator idle air mixture is set on 2 1/4 turn..

Does anybody regonize this problem, or/ and have further suggestions what to do?


Thanx in advance,

Svanosossie

[Gr8Grady]

Since everything works great till i's under a significant load - it's likely the thermocouple for over temp.

Check the impeller. If it's significantly fallen apart, them:
1. replace it
2. remove the strainers in the lower unit and remove any bits
3. run it on the hose with the thermostat cover off to get all those little bits of impeller out of the engine.

[tmann45]

Hello,
The things I have checked and switched from the 15 hp model is.

-Fuel pump

-ECU unit

-Ignition coil

-Spark plugs

-Carberator cleaned

Svanosossie

What about the fuel line, filter and tank?

[tmann45]

Hello,
The things I have checked and switched from the 15 hp model is.

-Fuel pump

-ECU unit

-Ignition coil

-Spark plugs

-Carberator cleaned

Svanosossie

What about the fuel line, filter and tank?

Will it restart after a minute or two, or does it need to cool down before running again?