2008 205 Sport - Alarm @ ~3000 RPM

[WhyKnot205]

Have had this boat for a few years now. Had an issue with this alarm sounding shortly after I bought the boat. Discovered engine oil was very low. Completed an oil change including the oil filter, replaced fuel filter. Alarm gone. Runs like a champ.
About 2 years later, the alarm has reared it's head again. The strange thing is, like before, it only sounds at 2900 - 3100 RPM. No loss in engine power. In fact I can throttle back or up and the alarm will go away instantly.
Engine temp maintains 170 degrees
Oil pressure steady at 60 (oil level in operating range)
Voltage steady ~14V
Any suggestions for trouble shooting would be greatly appreciated!

 

[Lazy Daze]

Your boat will only sound an alarm for low oil pressure, high engine temp or low drive fluid level. If all of those things are physically good, then it could be a flaky sensor. Check level of drive fluid and report back.

 

[WhyKnot205]

Oil level is in operating range, temp maintains 170, drive fluid maintains full level. Had outdrive removed this season to check for bearing alignment, seals etc., all checked good. I'm thinking it's a flaky sensor too. Especially that I have absolutely no engine performance issues even when the alarm sounds. The strange thing is in ONLY alarms between 2900 - 3100 RPM. I don't run WOT very often, but when I do there are no alarms. Lower RPM no alarms either.
Thanks for your quick reply to my original post.

 

[Lazy Daze]

You may be able to narrow down which sensor is flaky... or at least which system is causing the issue... by systematically disconnecting the sensors (not the senders). I am certain that you can disconnect the drive fluid sensor and it will NOT sound the alarm. I "think" you can do the same thing with the other two. But, either way, it's easy enough to figure out if this can be done and won't cause any damage in any way if it does sound.

Oil pressure sensor could be flaky, or possibly a little piece of dirt on it that only covers the sensor at a certain rate of oil flow.

Temp sensor could be flaky, or there could be something stuck in the t-stat housing that is disrupting water flow. That could cause turbulence at a certain rate of water flow past it... ie: air, which heats up much faster. If t-stat was changed just recently, may have been installed incorrectly. Housing can be removed and CLOSELY inspected (look in all passageways) for obstruction.

When the OD was removed, was the impeller changed? Was it 100% intact, or missing any pieces?

Once you figure out which system is the issue, it'll make things easier.

 

[WhyKnot205]

I did install a new t-stat the first year I owned the boat. I will follow your suggestion of systematically eliminating one sensor at a time. Through process of elimination rule one out at a time.
The impeller was inspected when the outdrive was removed. No issues reported. This is the third year on the impeller.
I intend to be on the water again this weekend and will begin the process of disconnecting one sensor (not the sender) at a time. I will report back.
Your detailed responses are greatly appreciated.

 

[Leardriver]

Unplugging either one of the electrical wire leads on the gear lube reservoir just takes a second. They are bullet connectors.