Yamaha Lack of Power and missing

[captain easy]

Hello,

I have an older 1991 GW Sailfish with twin Yamaha L-200ETD outboards. Lately I have noticed that one motor will not run above 3500 rpm, and will miss and knock if I try and advance the throttle further. I have changed plugs, fuel water separators, and cleaned primary fuel filters. The boat is used weekly with fresh gas. I have also tested all six coil packs and verified that they all have 3900 ohms. I also removed the carburetor bowel screws, and sprayed carburetor cleaner in the bowels. The problems continues to get worse. When I first noticed the problem, I felt the motor missing, but could still get 4500+ rpm. Now I can only get 3500 rpm. I feel like I need to perform a compression check before I go on. The motor will idle all day long, doesn't smoke more than normal, and runs fine below 3500 rpm. I have heard that I should check for foreign matter in the fuel lines as they enter each carburetor. How does the ignition system on this motor know how and when to advance and retard the timing? Is it through a throttle position switch? How do I test if the TPS switch is OK? Any ideas out there on what I should do next?

Thanks,

Captain Easy

 

[Snobike Mike]

Re: Yamaha Lack of Power and missing

This should probably be moved to the appropriate forum.

Cheers.

 

[rodbolt]

Re: Yamaha Lack of Power and missing

move it to Yamaha forums and we can help. we will also need both engine model numbers, I doubt they are both L motors.
your coil readings are wrong as well but most likly due to incorrect test method.