Tohatsu 40 M40C loosing loser after running WOT 🤷‍♂️

[Lured_lures]

Working on a new to me Tohatsu 40 M40C, issues running once hot. It will loose power and stlowly choke itself out after about 20 min WOT. Cleaned carb changed plugs / gas. It was missing the cover on the front of the air box so I replaced that. It also pulls air into the gas line after running even at idle, there is a visable air pocket and you can squeeze the ball. It’s possibly important to not that the motor will run better some days than others but usually has issues starting back up after it’s been ran and will die as soon as you give it gas when in gear. Now it will do it even at idle, however it you choke it it will fire but you have to put the choke in immediately and give it gas. Tried different fuel types, cleaning carb, new plugs, fuel line / tank. I also saw a backfire coming from inside the carb while trying to start it after it broke down on the water. Usually once it gets hot and sometimes it’ll keep puttering until it chokes itself out multiple times. I have to do the choke dance then quickly put it in gear and goose it so it doesn’t shut off, but that’s only once it been ran for over 30 min. Any advice or insight would be more than appreciated, thank you in advance!

 

[Lured_lures]

Tohatsu 40 M40C loosing power after running WOT

Working on a new to me Tohatsu 40 M40C, issues running once hot. It will loose power and stlowly choke itself out after about 20 min WOT. Cleaned carb changed plugs / gas. It was missing the cover on the front of the air box so I replaced that. It also pulls air into the gas line after running even at idle, there is a visable air pocket and you can squeeze the ball. It’s possibly important to not that the motor will run better some days than others but usually has issues starting back up after it’s been ran and will die as soon as you give it gas when in gear. Now it will do it even at idle, however it you choke it it will fire but you have to put the choke in immediately and give it gas. Tried different fuel types, cleaning carb, new plugs, fuel line / tank. I also saw a backfire coming from inside the carb while trying to start it after it broke down on the water. Usually once it gets hot and sometimes it’ll keep puttering until it chokes itself out multiple times. I have to do the choke dance then quickly put it in gear and goose it so it doesn’t shut off, but that’s only once it been ran for over 30 min. Any advice or insight would be more than appreciated, thank you in advance!

 

[pvanv]

Sounds like fuel starvation. What method did you use to clean the carb? Is the float height correct? If you are sucking air, check for where that could leak in. Uusal problem is connector at the tank or at the motor.

 

[Sea Rider]

Is the motor running with correct plug type well gaped to factory specs ? If fuel connectors at any of both sides are suspect of letting air in, wind severeal roundds of electric or duct tape to cover the whole lenght of the male/females connector at both fuel line sides. If primming the bulb repeatedly when motor wants to die cancels the issue ? Test both situation running the motor at load while pushing the boat.

Is the time advance adjusted spot on to 25 deg as factory stated with respect to when the throttle grip it's at its max far position, that's with carb butterfly fully opened ? Check....

Happy Boating