Tohatsu Mode M40C

[dog209]

I got a little problem with my Tohatsu outboard motor , It was really hard to start the motor at the fist time . So i did clean up the carb , change the spark plugs , new fuel pump gaskets , impeller ... after all that done .The motor cant idle, about 3 or 4 min and it shut down . So i took the boat to the water to test it again at this time the head gasket burn out ... i had no idea why is this happen cause i just change the impeller , the water pump fine . Replace the head gasket today and did the compression test only 85 psi ( really low ).But the problem from the beginning still there ..hard to start at the fist time , cant idle over 3 or 4 min . The guys at mechanic shop did a test on the carb and said" it fine" . Nothing wrong with that . So i cant identify the problem now ... please help .

Thank You

 

[Sea Rider]

Re: Tohatsu Mode M40C

When compression is low, it's hard to start, what happens when at idle and start openning the throttle, engine dies fast ? probably had a cylinder head overheat because of a faulty thermostat, check. How is your fuel line, small internal connectors o'rings, are engine and tank pick-up filters clean ? When engine dies, do you need to prime again to start ?

Happy Boating

 

[dog209]

Re: Tohatsu Mode M40C

When compression is low, it's hard to start, what happens when at idle and start openning the throttle, engine dies fast ? probably had a cylinder head overheat because of a faulty thermostat, check. How is your fuel line, small internal connectors o'rings, are engine and tank pick-up filters clean ? When engine dies, do you need to prime again to start ?

Happy Boating

Thank you so much for your reply . I did change all my fuel line , fuel filtter ..after the engine shut off gas still had alot in there .. No need to frime again .But won't start again without a chocke on .. And will have a lot of smoke come out .Open the soak plug it wet and brown color .With the compression proplem now should I replace the ring or anther way to deal with it without open the head out ?

Thank you again .


Thank you so much for your reply . My fuel line was fine , I did replace all new fuel line around the motor , fuel

 

[TOHATSU GURU]

Re: Tohatsu Mode M40C

You need to pull the cylinder head and do an inspection at this point.

 

[Sea Rider]

Re: Tohatsu Mode M40C

How old is that engine for being so low on compression ? Had a similar experince with a 30, same problem, was completely overhauled to new, now fires right up. Was new head gasket torqued to specs ? if so, prepare wallet, credit card, whatever, maybe your engine needs a complete overhaull cowl to tail. The minimum investment would be: piston ring change + gasket set asuming cylinder walls and pistons are ok to accept just new standard rings. Will need to tear apart engine cranckase to change new rings, pistons, rebore, whatever needs to be done, take advantage of it to check all ball/needle bearings, all moving parts condition.

Happy Boating