Is it cavitating?

[seadooNY575]

Im a total newbie and just took my used 96 Sportster on the water for the first time this weekend, the engine was rebuilt a couple of years ago and seems to run fine, the boat got up to speed alright and I took it up to about half throttle for a half hour, however, once I brought the throttle to idle and tried to accelerate I would get this loud winding/rattling noise and no thrust. It sounds to me like the impeller is turning but not moving water about. Afterwards I had to limp back to the boat ramp because even at idle my thrust was weak. Do I need a new wear ring/impeller?
Thanks.

 

[kustomkarl]

First I would look in the jet pump for any thing that might be stuck in there. It could be a plastic bag or a stick that is causing the loss of power. If it is clear it just might need a wear ring. Here are the specs on the wear ring if the pump is all clear. Check for any large gouges or scrapes too.

Wear Ring clearance for your seadoo 1.0 mm or (.040in) Measure the clearance at the center of the impeller blades, with a 12” long gauge. Measure the clearance from the venturi side of the jet pump.

Keep us posted on your findings.

Karl

 

[seadooNY575]

Thanks Karl, I'll check for that first.
Dan

 

[seadooNY575]

Heres the update, I checked the intake side of the impeller and did not see any debri, I then checked the nozzle (venturi?) side and did not see any debri there either. The impeller blades are smooth and each has one or two tiny nicks, no bigger than a mm, along the edges and although I did not have a tool long enough to measure the impeller/wear ring clearance, it seems to be no greater than 1mm. I did not remove any parts, do you think it may still be the wear ring or something else?
Thank you.
Dan

 

[unclejay]

Possble that...

There was something in the intake and it fell out while trailering, that happens a lot. Wear ring problems don't happen suddenly like that. I know its a pain but Id run it again in water maybe the problem went away. Check the lube in your PTO
(owners manual says how) also. Pull plugs look for melted metal, white flaky material, damage to electode. Is there oil in the oil lines ? Does it start OK ?

 

[kustomkarl]

Dan if the impeller looks pretty good and the wear ring doesn't look damaged it is possible that you had a stick or something that might have jared loose even sitting at idle. If all looks good yes run it again and see if it does it again. If so, try to isolate where it seems to be making the strange noise.

Keep us posted.

Karl

 

[derek]

if still no thrust, pull pump off and re-seal it to the hull. nice thick bead of silicone where the wear ring goes in. boats are much more sensitive to a small air leak than skis.

 

[unclejay]

Great Minds

KustomKarl and Unclejay said the same thing. Great minds think alike !

My sister lives in Englewood, I live in Arizona, how i envy you living near the intercoastal ! I have to do a long trailer to get near any water !

Only bad thing about SW Florida, boat storage is a pain, a lot of those 4-tier stacker hanger dealies. No way.

 

[kustomkarl]

My lift is water side as seen in my avatar...takes me like 2 minutes and I'm off, but I have a small ride to the ICW from my lift.

Karl

 

[seadooNY575]

I am happy to say that I finally took it out this weekend and it ran fine, that is up until I got more seagrass/seaweed on the intake grate. So a clogged up intake was my problem. Unfortunately, there is alot of grass around up until you head further out into the ocean. My only other question is what can I do to minimize this? The intake grate resembles a fork with the open parts in the direction of travel, Im afraid that its essentially raking up grass. Thank you all for you help.

 

[Lee]

I am happy to say that I finally took it out this weekend and it ran fine, that is up until I got more seagrass/seaweed on the intake grate. So a clogged up intake was my problem. Unfortunately, there is alot of grass around up until you head further out into the ocean. My only other question is what can I do to minimize this? (quote)
Next time it clogs up shut the engine off,wait about a minute and restart it,that usually is enough time for the debri to fall off,if that doesn't work try idling further away and try again.It happens to me at least once an outing.

 

[gerapau]

Or try this, put the boat in reverse and go as fast as you can backwards and cut the engine (do not slow down before cutting the engine). Do this a few times if you have to but it has worked for me every time so far.