1997 75HP 2 stroke 3 cylinder Stalls on high speed

1997 75HP 2 stroke 3 cylinder Stalls on high speed

This is my first post and and hope to find some answers.

I purchased the boat last fall and used it a couple of times. This spring I started the motor on my driveway and felt that it needed a service. I had the spark plugs and the lower unit oil changed. It still had a lot of old gas in the tank and I was advised to just use up all the old gas and to fill up with new gas.

I did exactly that this past weekend. the boat ran well with the old gas and I refilled with new gas (approximately 32 liters). I used up about 3/4 of the gas and noticed that when I accelerate to the fastest setting, the boat stalls. It runs okay at lower speeds.

I noticed that the primer blub was sucked in and it seemed hard to prime. I removed the quick connect that connects the prime bulb to the motor and and it seem to prime well. I'm assuming that there is some sort of fuel block. I plan on replacing the inline fuel filter tomorrow.

I would like to know if anyone else has experienced anything like this in the past and if so what the problem may be. The marine mechanic that performed that service recommended that I clean the spark plugs as there may be some water in the gas. He asked that I continue to do that until the problem disappears.

Any help would be greatly appreciated.

If the primer is collapsing there is a restriction somewhere. The tank vent open?
The vent line could be clogged with wasp nests.
Something in the tank clogging the pickup?

if the bulb is sucking flat then everything from the bulb forward towards the engine is ok...with the bulb sucked flat when you crack the fill cap on the tank can you hear air entering the tank?if so you have a vent problem...if you dont hear air dont draw a hard conclusion on it but it may be the bulb or line feeding it from the tank...there may also be a filter on the end of the pickup line in the tank...