CDI unit

Just wondering if anyone has had any trouble with or had to replace a cdi unit.

I have a 2 stroke 90hp Yamaha and had the 100hour service done today.
The mech wasnt happy with the motor at idle. Sometimes, not always, the motor seems to running on 2 cylinders at cold start.

So we went for a run off Wello this arvo. Cold start was fine and idled perfect.
Got to the end of the beacons, 2minutes run, and the mech says, turn it off and restart. Restart, runs, stops after 3 seconds. Did this 5 times untill the mech took the cover off , took the lever off the cdi and manually advanced something.

Fired up and kept on running,,, and didnt do it again. After a lot of starts.

Also, if you take 1 of the plug leads off at idle, the revs increase.

The cdi unit apparently controls everything to do with the motor.
Maybe one of the sensors is stuffed.

Has anyone had any of the above problems or had to replace the cdi unit .

Rod

[boats.net]

I don't recall having a CDI causing engine to shut of but have had to replace CDI due to problems with timming advance in CDI.

I had the same problems with my 2 stroke Yamaha 40hp 3 cylinder. The same thing where the motor would crank just fine and run for about 15 seconds, then act like it was running on 2 cylinders. You could pull the bottom plug and it wouldn't make any difference at all. I also advanced the timing a bit on that CDI box and it seemed to help.

I solved the problem by replacing the Yamaha with a 50hp Johnson and haven't had a problem since...