2000 90hp yamaha 2 stroke will not run on all 3 cylenders

[Mikey01]

I have a 2000 90 hp Yamaha outboard motor after i run it for about 30 min. then stop to fish for about 1 hour the motor runs on one or two cylinders. Then i have to start it about 9 or 10 times to make it to run on all three cylinders I have been to three mechanics they cannot figure out what it is. They have replaced the power pack, cleaned the carburetors, and changed the Pulser Coil Bushing(trigger). I bought the motor brand new it started after about 6 months after I purchased it. Please help mike

[boats.net]

Was the compression good? Did they test to see if lossing fire to cylinders? Does it help if pump the fuel primer bulb?

[Mikey01]

Yes the compression is good. No thier is no lose of fire to the cylinders. No it does not help to pump the fuel primer bulb.

[99yam40]

Have you checked the fuel pump diaphragm for holes?
Does this motor have the Prime Start Enrichment system or a choke?
If it has the prime start switch the red lever to the off position to see if that will help with the warm restarts.

Testing the inputs and out puts of the cdi should be easy while the problem is occurring to see if it is ignition related if you have the proper equipment and it occurs every time. As a matter of fact this should have been done before replacing parts that were not needed.The Yamaha service manual gives the steps for testing, the specs., and the equipment needed for testing.
An inductive timing light will indicate if there is spark missing on spark plug wires
If that is not the problem then look at all fuel related things. Too rich or too lean of a fuel/air ratio will not let the cylinder fire properly even if it has good spark