1999 200HP Yamaha 0x66
I just went over 110 hours this season on the motor and completed the following maintenance:
Checked fuel rail pressure @ 35psi
Checked TPS baseline voltage @ 5.04V
Checked throttle valve synch
Adjusted TPS sensor to 5.00V w/ throttle valves closed
Checked O2 sensor output @ .6-.7V
Changed Racor fuel/water seperator
Changed spark plugs
Adjusted oil control rod to stop w/ throttle valves closed
Plugs looked ok, with a few small carbon 'balls' loosely attached. O2 sensor is new this season, no carbon build-up on it, but the outside of the draw tube was filled in with Carbon. I soaked in RF and scraped it off. I always run with Yamalube and Ring Free.
While running the O2 sensor diagnostic with the test harness (boat in water), I noticed that the voltage swung between .6V and .7V. Blocking the hole on the top throttle valve would cause the voltage to swing, but not in the .3-.9V range as I expected. I noticed the same behavior this spring when commissioning the outboard and after installing the new O2 sensor.
Before service, the engine was idling a little rough, but no problems getting above 5k RPMs, WOT was around 5600K. Noticed that when I run the engine tilted way up idling out of dock area, there is a lot of extra smoke when I trim the motor back down. One cold morning the engine actually stalled a couple of times after trimming down.
After service, engine sounded stronger at idle, probably due to clean plugs. Fuel/Water seperator had absolutely no water or debris.
Ok, enough history and on to my question.
My usual start-up routine is simply to turn the key for 1-1.5 seconds, no problem. A couple of times before and after my service I have turned the key the same way, but the engine wouldn't start after maybe 2 seconds. I would turn the key again and it would start right up, no problem, and would never have problems starting throughout the rest of the trip and repeated starting/stoppings.
To paraphrase Rodbolt - what is my engine telling me?
-- Tom
I just went over 110 hours this season on the motor and completed the following maintenance:
Checked fuel rail pressure @ 35psi
Checked TPS baseline voltage @ 5.04V
Checked throttle valve synch
Adjusted TPS sensor to 5.00V w/ throttle valves closed
Checked O2 sensor output @ .6-.7V
Changed Racor fuel/water seperator
Changed spark plugs
Adjusted oil control rod to stop w/ throttle valves closed
Plugs looked ok, with a few small carbon 'balls' loosely attached. O2 sensor is new this season, no carbon build-up on it, but the outside of the draw tube was filled in with Carbon. I soaked in RF and scraped it off. I always run with Yamalube and Ring Free.
While running the O2 sensor diagnostic with the test harness (boat in water), I noticed that the voltage swung between .6V and .7V. Blocking the hole on the top throttle valve would cause the voltage to swing, but not in the .3-.9V range as I expected. I noticed the same behavior this spring when commissioning the outboard and after installing the new O2 sensor.
Before service, the engine was idling a little rough, but no problems getting above 5k RPMs, WOT was around 5600K. Noticed that when I run the engine tilted way up idling out of dock area, there is a lot of extra smoke when I trim the motor back down. One cold morning the engine actually stalled a couple of times after trimming down.
After service, engine sounded stronger at idle, probably due to clean plugs. Fuel/Water seperator had absolutely no water or debris.
Ok, enough history and on to my question.
My usual start-up routine is simply to turn the key for 1-1.5 seconds, no problem. A couple of times before and after my service I have turned the key the same way, but the engine wouldn't start after maybe 2 seconds. I would turn the key again and it would start right up, no problem, and would never have problems starting throughout the rest of the trip and repeated starting/stoppings.
To paraphrase Rodbolt - what is my engine telling me?
-- Tom