Tohatu M40D has almost no power

[Bryan_h]

Hi, I am Bryan from the Netherlands.

I recently purchased an 1997 Tohatsu M40D Automixing. It has about 100 working hours. I have installed it on my boat and I have got almost no power, runs rough and shakes when I put it in forward. The power comes only from the top cylinder. (It will go 25 mph, eventually, so no rev. limiter.)

On the waterhose; It starts perfect on only the top cylinder. Disconnect the spark-cable of the top cylinder and the motor almost dies, as if the bottom cylinders only do 10% of the power. When you pull the cable loose from the bottom cylinder, almost no difference is noticeable, so it doesn?t do much.

What I have checked:
No overheating.
Oil is full, sensor is up.
Compression, all of the three cylinders very good, bottom one even better.
spark-plugs are new, they all fire well.
Cleaned all carbs, were clean and still are.
Checked the coils, changed them from 1 to 2/3 but no result.
Got out all the reed-valves, they were clean and sealed well.

What can it be? In my opinion only the CD unit is left.. But can it be broken? Is it possible to test it? What does it do when its broken/faulty? Will it kill the firing or the timings? Because sparks are visible..

I hope someone recognizes this problem.

Bryan

 

[TOHATSU GURU]

Re: Tohatu M40D has almost no power

"It starts perfect on only the top cylinder."

A three cylinder engine does not start perfectly on only one cylinder....You need to get the engine into a mechanic or get a service manul which will have all the test procedures in it.

 

[Bryan_h]

Re: Tohatu M40D has almost no power

That is no answer. I have told everyhing I have done, everything I can do, but you tell me I have to check the manual. If you don't know the answer, please don't reply. I asked what the CD unit does when ist is faulty.

I am sorry if I am rude, but I expected some more expertise.

 

[deejaycee_2000]

Re: Tohatu M40D has almost no power

I must agree with you, what is the point of looking for answers on how to fix your motor in the repair and maintenance section, when the only response you get is take it to a mechanic ..... that is really just stupid ... the whole point of this website is to help people fix their motors themselves .... otherwise you would have taken it to a mechanic in the first place ..... Bryan, I doubt the CDi is faulty, you can test the output of the coils to make sure the spark is strong .... I would suggest taking off the air cover and see if your choke works properly, cause it sounds to me like it doesn't open the butterfly properly ....

That is no answer. I have told everyhing I have done, everything I can do, but you tell me I have to check the manual. If you don't know the answer, please don't reply. I asked what the CD unit does when ist is faulty.

I am sorry if I am rude, but I expected some more expertise.

 

[pvanv]

Re: Tohatu M40D has almost no power

Bryan,

If you are convinced that compression, ignition, and reeds are good, then the only remaining option is fuel, which would lead one to revisit the carbs -- which can look OK but still be faulty...

"I have told everyhing I have done, everything I can do, but you tell me I have to check the manual."

But... we really can do more troubleshooting than has been done so far. Yes, you have done some solid, initial, in-the-field diagnostics... yet you still have not identified the specific problem. Now it's time to move the troubleshooting up a notch. TG is correct to suggest a Factory service manual. Sounds like you are probably experiencing a single-cylinder malfunction, which, given good compression, could be caused by either ignition or fuel problems. the manual will have troubleshooting procedures, and is money well spent.

FWIW... if, hypothetically, you were to bring this motor to my shop, the first resource I would use would be the Factory service manual.

 

[Bryan_h]

Re: Tohatu M40D has almost no power

Ok, thanks for the replies. I will buy a service manual. But I still think it will not help me. If it almost can't be the CD unit, there must be something I missed. I will find it.. When I find out more, i will post it here.

Bryan

 

[Bryan_h]

Re: Tohatu M40D has almost no power

Here, A sample of what happens in the water.

http://www.youtube.com/watch?v=B6yGkfAzDsY

Don't mind the comments, It is Dutch and I was talking to my grandpa

Maybe someone recognizes it by watching the motor and listening to it..

 

[TOHATSU GURU]

Re: Tohatu M40D has almost no power

There should be a law requiring minimum intelligence to have access to the internet....

From this point on I will not be responding to any post on iboats unless the person asks me for help directly.

 

[Bryan_h]

Re: Tohatu M40D has almost no power

There should be a law requiring minimum intelligence to have access to the internet....

From this point on I will not be responding to any post on iboats unless the person asks me for help directly.

"minimum intelligence to have access to the internet...." do you think you are smart enough for the internet?


"From this point on I will not be responding to any post on iboats unless the person asks me for help directly."

I don't think it's very helpful to say that I should go to a mechanic when I have a question. When I have a problem with my Tohatsu, I go to forums to see if anyone can help me with some knowledge and experience. That is what these forums are for isn't it? If everybody just directly bring the engine to a mechanic, this forum would not exist.. Am I wrong?

 

[tristanos2]

Re: Tohatu M40D has almost no power

Hi, i am tristan and iahave the same problem with my tohatsu m40d.finally you have found the solution with the problem of your outboard. In requesting to give me an answer on the solution of problem if you have found also you.
thank you.

 

[deejaycee_2000]

Re: Tohatu M40D has almost no power

Welcome to the forum ..... Check your coils, see if you have strong spark, also check your compression .....

 

[John_S]

Re: Tohatu M40D has almost no power

I have a 40C and 18E and highly recommend a manual. The factory manual is probably prefered. There are many procedures that would be very hard to describe in the forums. The throttle position to timing advance being one. Also, for your model, carb syncronization would be of interest.

 

[tristanos2]

Re: Tohatu M40D has almost no power

I have already check all these. But what about the seals between the crankshaft.Does anybody know something?how can i find a service manual.I am from Greece and that book it is not sold here.can i download it? does anybody know the level of the compression ? thanks for your time.

 

[Alumarine]

Re: Tohatu M40D has almost no power

edited...

There should be a law requiring minimum intelligence to have access to the internet....

From this point on I will not be responding to any post on iboats unless the person asks me for help directly.

 

[lucy dee]

Re: Tohatu M40D has almost no power

i have the same engine check the stator and replace the plugs also may wanna check the carbs under a load i.e. in the water have a buddy run it and see if they are all spraying clean and equal, by the way what is the compression spec for this motor

 

[deejaycee_2000]

Re: Tohatu M40D has almost no power

if the crank chaft seals are leaking then you will still have power, but the moror will not be idling well or at all .....