twin yamaha 70hp problem

[henrysmako]

HI
I have twin 70 in a mako 19 and in load they wont go until
2400 rpms in both, we check props change it with smaller and do the same we repair carburators do a tune up even check with an external tank and the same the cdi where advancing checking it taking out the linkage and doing it manually and the engines advance. but try to check timming with an induction light ( craftman) and no timming light in neither 3 cyl checkl the light in a car and it works perfect put it back in the outboard and nada. nothing.
what I have to check then when these engines do nor rev up in load , apart of gasoline.
they go up in neutral 6000 rpm in the tach but in load 2400 in both engines end they sound perfect in idle until 2400 no misfiring or anything they just wont go up
thanks

[99yam40]

put timing light back on , but turn it around( arrow pointing away from plug).
This worked on the snap on light I have..
I believe safe mode will retard timing to limit RPM on that motor, so you need to teat alarm system to see if it is functioning as it should

[henrysmako]

sorry but how do I test the alarm sys.? about the timming light will do it this afternoon

thanks

[henrysmako]

sorry but how do I test the alarm sys.? about the timming light will do it this afternoon

thanks

[pafishhunter]

Did you resolve your issue? I have the same issue with an 03 4 stroke 60hp high thrust that I bought used from a private owner. I get 2800 rpm under load but can get over 5000 rpm in neutral. A Yamaha rep told me the motor control module is sensing a torque issue and limiting the rpm. It seems that the lower unit was replaced with a mid range unit with a 13 spline prop shaft and the high thrust is a 15 spline. The options I was given were; replace the lower unit or try a larger dia lower pitch prop. I am also trying to find out if the module can be replaced with a mid range unit but have not got an answer yet.

[boscoe99]

Did you resolve your issue? I have the same issue with an 03 4 stroke 60hp high thrust that I bought used from a private owner. I get 2800 rpm under load but can get over 5000 rpm in neutral. A Yamaha rep told me the motor control module is sensing a torque issue and limiting the rpm. It seems that the lower unit was replaced with a mid range unit with a 13 spline prop shaft and the high thrust is a 15 spline. The options I was given were; replace the lower unit or try a larger dia lower pitch prop. I am also trying to find out if the module can be replaced with a mid range unit but have not got an answer yet.

Better to start your own new thread. This one is several years old. And know that two different motors can have the same symptoms but have completely different problems. Two guys might have a similar headache. One is because of some heavy drinking the night before. The other has a brain tumor and will die in several days time.

Whatever RPM's are being obtained in neutral is completely irrelevant. Only thing that matters is RPM under a load.

The brain of the motor does not sense torque. RPM is limited only because of over temperature or low oil pressure.

The only difference between a T60 and an F60 is the lower unit. Swapping either lower unit for the other would have some affect on the WOT RPM, assuming the same propeller was used on both, but nothing to the extent that you are seeing. Because of the propeller shaft spline configuration I am presuming that the correct propeller is on the gear case.

Assuming the motor is in mechanically good condition (compression) then I would focus on a fuel issue. Maybe have someone spray/mist a bit of gasoline into the air intake system when it won't go over 2800 with a load and see what happens.

12 year old carburetors. When were they last inspected/cleaned?

[bajakeith]

Always a good laugh here

Why do fools and more fools think for a second that they are going to Diagnose and Test,,Correctly Repair and Fix their marine propulsion power plant ???

[Dashunde]

Why do fools and more fools think for a second that they are going to Diagnose and Test,,Correctly Repair and Fix their marine propulsion power plant ???

Why, exactly, are you here?

Not sure about the rest of you other fools, but using forums just like this I've manage to figure out, and repair, quite a few "modern tech" contraptions that I knew very little about when I started in.

I guess we should all stop trying to do things for ourselves and learn something along the way...

[zenoahphobic]

Sometimes posters clearly break the forum rules, and sometimes need to explain themselves.
I suspect the comment is a bit more complex.
Not necessarily equating this to this thread, often a conclusion is made on the basis that there has been clear neglect or lack of understanding of maintenance that that person would not have the capacity to diagnose a fault let alone fix it.
But we all have the right to stuff things up in order to learn, if we can afford that luxury.
Again not specifically critizing any individual, some people simply don't have the goods. But how can we really tell through a forum.

[pafishhunter]

Power unit was remanufactured in 2013. I will try the gas mist this weekend. The tach was not connected when I purchased the boat. Do you know if the stator is 6 or 12 pole? Thanks for the response, I am new to posting on forums and tried to post a new thread but something went wrong