Sudden thrust lost, went away after turning boat off for a bit

[grumpygoat]

I bought a brand new 2020 Yamaha 195S this season. I recently had it in for its 10 hour service and oil change and they said all was well. It's been awesome and I love the boat. However, something happened last night.

I was out on the boat yesterday with my family (5 adults, 3 kids). We were on a fairly open part of Lake Ontario, so the waves were very noticeable but not too bad. After roughly 20 minutes into the ride I heard a sound that's hard to describe, almost like a mechanical click or thud. This immediately followed with a huge loss of power. I turned off the boat and checked the impeller clean out port and it was totally empty. I felt around for any foreign objects to no avail. I started the boat and told everyone we were heading back to the marina.

With RPMs at almost 5K, we were able to hit about 9 miles per hour. I didn't want to push the boat too hard, but we also had to get back home. Any time I would open the throttle, I would feel vibrations and a shakiness throughout the boat that aren't normal.

We eventually made it back to the bay and the family asked to swim in the lake before I docked her back at the marina. I said yes and anchored the boat. 30-45 minutes later I go to start the boat and I noticed it sounds better than it did before. As we take off and continue heading for the marina, I slowly open the throttle, getting a normal response as I do. I was able to open the throttle all the way and reached a typical speed for the passenger load I was carrying.

My slip-neighbor is fairly knowledgeable with boat motors and said that it sounds like I could have taken a big enough wave that I sucked up air into the impeller and the boat's computer went into "limp mode", however I don't think we hit any waves (they weren't that big) that would have lifted the boat out enough to suck air up.
So, what could cause a sudden loss of power that isn't debris in the impeller, and go away after several minutes of the boat being off, keeping in mind that I did turn the boat off for a minute or two when this initially happened so that I could check the intake port? I'll be taking the boat out again this morning to see if it happens again. If it does, I'll be taking it in for warranty service.

 

[buckbuck]

Sounds like classic cavitation issues to me. Is is possible you overlooked something? Perhaps a twig on an impeller blade?
I don't think you need to take it in for service.

 

[PeterB]

I had a similar experience and on second inspection of the impellers found a small piece of twig still jammed at the edge of the impeller. Hard to see and remove but once clear everything was fine. I now carry some long needle nose pliers and hook shaped razor blades to help clear. There is also a thread on the forum for doing a reverse clear removal where you get some reverse speed up then quickly shut the engines and put in forward to lift the buckets out of the way and it often washes out debris - use search on this forum to find better descriptions but I found it very helpful

 

[Beachbummer]

Symptoms match 100% to a small piece of debri in the wrong place. Issue is not super clean... I have found a spray can cap and wood pieces this year, causing the exact same symptoms.

Everything is fine, I humbly suggest you don't spend your time taking it for service. It's running great, and there's nothing they can do for you at this time beyond taking your boat away and wasting your time.

Best of luck!

 

[grumpygoat]

Thanks everyone. I'm about to head out and test it out on the water. I'm hoping it's fine and doesn't have any issues. I'd hate to lose more on-the-water time this year. It does sound and replicate like debris as I've had that happen before, but I couldn't see anything from the clean out port. In these situations, how would I typically go about investigating further? Would I have to dive under the boat and visually inspect? I'm not honestly not too technical with this boat, so I typically just reach my hand into the clean-out and feel around for stuff. Usually it's seaweed. Should I be trying to feel more towards the bow or stern of the boat to check for smaller pieces of debris?

 

[dshscarab]

Same as above. Definitely something on the impeller, shaft, or intake grate. You don't need to take it in if it is running fine. When docked, it probably fell out.