Ok, I need some help with my Mercury 90/65 (2002) 2-stroke, 3 cylinder jet motor. I was using it earlier in the year until it lost power - suddenly, at top speed it became about 2/3 of the normal speed for a few seconds, then recovered. Next time it happened longer and now all the time. It used to get top speed 30+ with just me, now just 20mph. Other than that it seems to work great; starts fine and runs great. I haven't been using it much until I can figure exactly what's wrong.
I have tried the following:
Changed spark plugs
Changed fuel filter
Removed and cleaned carbs (they were really clean; and floats moved free)
I also noticed the charging circuit on my battery voltage was crazy (flipping -100 to +100volts); so changed voltage regulator and now that is Ok but boat top speed didn't change.
I did have electrical fire in the motor 2 years ago; ground shorted out and melted a lot of plastic wires. I used some electrical tape and it worked fine - so repaired the wires that were melted and the motor was fine for the next year.
When using an inductive tachometer (very cheap one); I see lower chamber runs 1000rmp while top two would sit at 2000rpm testing last week. This week the same setup the lower one shows 4000rpm; which I know isnt' right. But it's different to the top two. Based on this I'm suspecting the Trigger may be bad (possibly Stator too, not sure). I've ordered a new trigger to try out which comes in a few days; since that's cheaper.
I've moved the CDM module between two spark plugs but the RPM's reported didn't follow; so I don't think that is an issue (unless my really cheap tachometer is lying to me - I've ordered another as a backup getting here soon).
Could a bad Trigger cause a loss of top speed? My guess is currently something with the CDM; trigger or Stator?
Any other ideas, or if I'm doing something wrong in diagnosis please let me know and send tips!!!!
Thanks
James.
I have tried the following:
Changed spark plugs
Changed fuel filter
Removed and cleaned carbs (they were really clean; and floats moved free)
I also noticed the charging circuit on my battery voltage was crazy (flipping -100 to +100volts); so changed voltage regulator and now that is Ok but boat top speed didn't change.
I did have electrical fire in the motor 2 years ago; ground shorted out and melted a lot of plastic wires. I used some electrical tape and it worked fine - so repaired the wires that were melted and the motor was fine for the next year.
When using an inductive tachometer (very cheap one); I see lower chamber runs 1000rmp while top two would sit at 2000rpm testing last week. This week the same setup the lower one shows 4000rpm; which I know isnt' right. But it's different to the top two. Based on this I'm suspecting the Trigger may be bad (possibly Stator too, not sure). I've ordered a new trigger to try out which comes in a few days; since that's cheaper.
I've moved the CDM module between two spark plugs but the RPM's reported didn't follow; so I don't think that is an issue (unless my really cheap tachometer is lying to me - I've ordered another as a backup getting here soon).
Could a bad Trigger cause a loss of top speed? My guess is currently something with the CDM; trigger or Stator?
Any other ideas, or if I'm doing something wrong in diagnosis please let me know and send tips!!!!
Thanks
James.