1988 40LG missing above half throttle

[mechmagcn]

When running at half throttle, my 40LG will start to miss occasionally on one cylinder. If throttled farther, it will drop the cylinder completely. I have cleaned the carbs, changed spark plugs twice. I disconnected the oil level and heat sensors to see if it was a problem with that system. On inspection of the ignition, I found that the lower cylinder has weak fire, I swapped coils from another cylinder with no change. How do I check the CDI unit to see if it is the defective?
One mystery to me, the motor misses when running the boat, but with it on the trailer, backed into the water, it will run on all cylinders. I have checked the compression, it reads 120 PSI +/- 2 on all three cylinders.
This is a tiller steered, manual start motor, but I have added electric start.
Thanks in advance for any help, Jeff

[99yam40]

Follow your manuals ignition system testing procedures

[mechmagcn]

Follow your manuals ignition system testing procedures

Excuse me, I thought this was where I could ask a question and maybe get an answer. If I had a manual, I probably wouldn't need to post here.

you need a dva and a good meter to test things out

DVA ????? I have a good meter, how do I go about checking the CDI with it.

[99yam40]

Excuse me, I thought this was where I could ask a question and maybe get an answer. If I had a manual, I probably wouldn't need to post here.


DVA ????? I have a good meter, how do I go about checking the CDI with it.

You can search the forums for the proper procedures to test certain motors , but I think you will find that no one has the time to type out all the needed steps and specs for all the motors that is why you are told to get a manual for your motor and then if you do not understand certain things you ask questions and hope someone can help you understand. the manuals are copyrighted material and you need to buy yours like the rest of us to get the info.