Diagnosis Day

[SantaFeTrailer]

Bah. Took the boat out for the first time in a few weeks. Worked fine last time out. Yesterday it was topping out at 13mph/6,000 RPM. Felt like I forgot to remove the trailer. Nothing obvious going on. Luckily we were on the foil so the day wasn't ruined (my 16 year old has definitely cracked the code on the foil - I didn't go out this trip because I was worried about the boat and wanted to monitor it).

Place your bet on what the issue is, and I'll let you know (this isn't helping my wife's opinion that boats never work, which I had hoped was just confined to our previous 25 year old outboard)

 

[2kwik4u]

Debris in the pump causing cavitation is my vote.

 

[biffdotorg]

Debris in the pump causing cavitation is my vote.

Any engine that revs that hard with no propulsion has to be cavitation. This is spot on, or your cleanout plug is not seated properly.

 

[RNYCLV]

Clean out plug
Did you get a Communication Error Code?

 

[SantaFeTrailer]

Yeah, checked the cleanout plug several times. Couldn't see or feel anything in the impeller, but I'll crawl under it and look after work. no error code - would that show up on the tach display?

 

[Julian]

Yeah, checked the cleanout plug several times. Couldn't see or feel anything in the impeller, but I'll crawl under it and look after work. no error code - would that show up on the tach display?

Stick your phone in the intake and take a bunch of photo....,much easier than trying to eyeball it. I'll be stunned if you dont have either something in the pump, or the plug not inserted properly.

 

[Sean R]

If you never have pull the pumps off, I would.. Then you can check the impeller out and grease the shaft. It's not that hard.

 

[SantaFeTrailer]

I replaced most of it last fall, so I am hoping to avoid that again!

If you never have pull the pumps off, I would.. Then you can check the impeller out and grease the shaft. It's not that hard.

 

[SantaFeTrailer]

Well, this is proving to be a conundrum. Nothing in the pump, sealant looks good. Cleanout plug in place solidly. Oil looks good, plugs look good (replaced them anyway, because I had new ones on hand). Supercharger clutch spins only one way, as it should. Bucket retracts properly.

My son asked an interesting question, which is whether the Ridesteady could be acting up. I disconnected it, and will take a test run tmw. After that, I need to go back to the Jet Set here for more ideas.

Thanks for the comments so far.

Edit: note that this is a 6000' elevation lake, so I'm not expecting strong performance, but it's clearly not working right.

 

[CaptRedbeard]

Other easy checks I'd make before your next trip out:
-spark plugs (if discolored, probably need replacing)
-oil level, color (high oil could backflow into the air filter, lowering the efficiency of the air intake process)
-air intake filters (check for dirt/oil)

Keep us posted

 

[sunbyrned]

I replaced most of it last fall, so I am hoping to avoid that again!

I’m with Sean. I would pull the impeller out. Even if you don’t see anything, This usually fixes the situation. Takes about 20 minutes tops.

 

[SantaFeTrailer]

Thanks, I'll do that.

One thing I noticed is all this discoloration around the *outside* of #3. I wonder if it was loose? (can't remember noticing that when I removed it).

 

[2kwik4u]

Impeller looks pretty good.

Have anything (even as small as fishing line) wrapped around the shaft? How does the rest of the tunnel look? Any missing sealant, or sealant flopping around/loose? Any sharp edges perpendicular to flow?

I see an L13 cone on there, and some sealant around the tunnel, those are good signs. At this point, I would pull the pump and inspect/clean/reinstall. Might be nothing, might find a small twig or something in there you can't see that's borking the whole mess up.

You won't get 6k rpm if the engine isn't running right, at least not on a 1.8L engine. My guess is that the engine is running just fine. The low speed/high revs really points towards a cavitation or some other loss of thrust. Even at 6k elevation you should be able to get on plane, and maintain 25-30mph. Might take a bit to get there, but 16mph is low.

Did you have a lot of people in the bow? 16mph is just on plane in my '17 AR190. I can't maintain that speed without setting RideSteady that low on purpose. Trying to do it by hand will have me just fall off plane. I could probably hold that speed if I had like 4 people in the bow and tried real hard to NOT get on plane.

OR.....you forgot to haul in the anchor.....OR.....you were towing another boat behind you........or something like that

 

[Julian]

Thanks, I'll do that.

One thing I noticed is all this discoloration around the *outside* of #3. I wonder if it was loose? (can't remember noticing that when I removed it).

Why is the head of that spark plug so caked in ????

 

[SantaFeTrailer]

It appears to be like corrosion. All the other plugs were totally clean, and it's only a year old. No indication of any water in the engine compartment. I was wondering if maybe the plug came loose if that would happen?

Why is the head of that spark plug so caked in ????

 

[2kwik4u]

It appears to be like corrosion. All the other plugs were totally clean, and it's only a year old. No indication of any water in the engine compartment. I was wondering if maybe the plug came loose if that would happen?

That looks like salt water or general water corrosion from here. Can't imagine it being on the spark plug without additional evidence though. Combustion gas is high in both H2O content as well as many other volatile compounds that combined with high temps could create similar corrosion. It would have to be pretty loose for that to happen, and I would suspect you weren't getting 6k rpm with a loose plug like that.

I've been wrong before though

 

[SantaFeTrailer]

All this makes sense. Definitely hasn't been near salt water though.
The plug bore doesn't seem corroded. I'll poke around the cylinder with a borescope tonight and maybe do a compression check to be sure.

\

That looks like salt water or general water corrosion from here. Can't imagine it being on the spark plug without additional evidence though. Combustion gas is high in both H2O content as well as many other volatile compounds that combined with high temps could create similar corrosion. It would have to be pretty loose for that to happen, and I would suspect you weren't getting 6k rpm with a loose plug like that.

I've been wrong before though

 

[2kwik4u]

All this makes sense. Definitely hasn't been near salt water though.
The plug bore doesn't seem corroded. I'll poke around the cylinder with a borescope tonight and maybe do a compression check to be sure.

\

Let us know what you find.

I'm still hoping it's just a twig in the impeller you can't see/feel.

I've had some absurdly small pieces get in there on the Ohio River and cause an issue. One was about 1/2 the diameter of a pencil and about 3/4in long. Took me "carving" it out with a pocket knife, in the dark, on the water for about 30min to get it out. Was so absurdly small I was pissed at the difference between effort I put in to removal and mass of object removed.

 

[SantaFeTrailer]

Pulled the pump, looks as clean as my criminal record after I paid that lawyer for an expungement. No indication of anything in the pump or wrapped on the shaft. Sealant looks good.

Scoped the #3 cylinder, and nothing looks out of the ordinary.

Hmmmmm

 

[sunbyrned]

So, from my experience, mine ran fine after this step. I never found anything either. My hope is that it will run just fine now. Thanks for giving this a try.