yamaha 60 hp 2 stroke cutting out intermittenly

[jetty]

I have a 2000 yamaha 60 hp 2 stroke that is on and off again cutting out problem at various speeds.I've eliminated fuel and have replaced one coil and have moved that new coil to each cylinder with no difference.
Sometimes it will run great then it cut out like it's running on just 2 cylinders,more so when I back off when on a full plane.
Someone told me it may be the power pack which is over $500 and almost impossible to find used.
Do power packs have intermittent problems like this or have I overlooked something else?

Any help would be greatly appreciated.

[boats.net]

It could be CDI, pulsor coils, charge coils, ignition coils as well as wiring or plugs, it's impossible to say which one without testing igition while it is dropping a cylinder.

[bcnuhawaii]

2 cylinders cutting out on 2001 Yamaha C60TLRZ

I have a very similar problem. The engine starts first crank, idles roughly for about 2 minutes and then settles down. Acceleration is good and planing rpm (3500) is smooth for about 1.5 minutes and then the engine slows to 2000 rpm (sounds like "slow mode"... yes?). RPM will stay at 2000 for 4 minutes and then problem goes away. This scenario continues to repeat like clockwork.

I suspected overtemp initially because of the repetitive timing of the problem so I checked the cylinder head temps... all about 125 degrees (needs to be about 165 degrees for thermal switch to close). I also disconnected the overtemp switch when problem was occuring... no help.

I removed plug wires until I discovered the top two cylinders were not firing... the engine was running on only the bottom cylinder. I don't know if the non-firing cylinders were receiving spark or not... did not have a tester with me... that will be the next thing to do.

I'm not really sure what Yamaha's well known "slow mode" does to the engine to bring it to 2000 rpm... sure would like to know. I thought it simply reduced the rpm via the CDI... but maybe it shuts down two cylinders???

I am beginning to suspect the CDI. Did you manage to fix your problem? If so, what was the cause.

Thanks... Bob in Gulf Breeze

[99yam40]

Probably fuel related, pull and clean carbs, but you need to rule out the loss of spark first

[geoff186]

Probably fuel related, pull and clean carbs, but you need to rule out the loss of spark first

can you hook up a timming light of a car to check weather its got spark or other way?