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My 2002 90 Yamaha 2 stroke has developed a problem that only happens at or near wot I can run 4000 to 4400 or so all day long but if I push it to wot (5000 rpm) within 1 minute it will start to surge and bogg down if I dont throttle back it will stall and start back up if I throttle back it will level out and do ok motor has 88 hours on it I have checked my Racor for water (none found) and I replaced the Racor filter Any ideas?
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GMiller,
Check the onboard filter for possible clogging.
Also, is the alarm going off when motor "boggs down"? You could be going into rpm reduction mode and the alarm buzzer not working. Disconnect the two wires that leads to the thermo switch in the head assy - two bullet connectors about four inches from the switch. Turn the ignition on (do not start motor) and momentarily short the two wires together (the ones that lead back to the ignition control) - the alarm should immediately sound telling you an overheat condition has occured. If no alarm, then alarm buzzer/circuit is faulty.
Good luck,
Ken K -
You can also check the primer bulb, at wot does the bulb collapse or go soft, if so you might have trash in your fuel tank, when you go to wot, the gas line pick-up in the tank could be sucking up trach and starving the motor for fuel.Comment
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Alarm is not going off and yes alarm is functional primer bulb seems to be somewhat hard I am thinking possibly air is being sucked in somewhere?Comment
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GMiller,
I'm thinking maybe fuel pump now - I believe there is a test procedure in the Yamaha shop manual, or a way to check the pump diaphram. Get yourself a Yamaha manual for your particular model - it will pay for itself.
Good luck,
Ken KComment
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