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Jmuir

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Boat Make
Yamaha
Year
2001
Boat Model
LS
Boat Length
21
2001 LS2000- For some reason the last couple of times i have been out it doesnt seem right, When I throttle up it doesnt move as fast as it used too- not as peppy, The motor REVS up like normal but it takes a little bit to really start moving..

A couple of weeks ago, I beached the boat and the waves put the boat sideways to the beach and kind of jammed my forward, reverse gates.. i had to get them unstuck- But it seems though since then its not as Peppy as it was most of the year. The gates are opening up all the way in forward, reverse etc. The motors sound the same- but again it doesnt seem to have the same pep?

any thoughts on what could be going on?
 

4x15mph

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Year
2018
Boat Model
AR
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Could be some cavitation going on. Check the clean out ports very carefully and check around the impeller. It doesn't take much
 

Jmuir

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Year
2001
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Could be some cavitation going on. Check the clean out ports very carefully and check around the impeller. It doesn't take much

Forgive me for not knowing what Cavitation is?

I take my clean out ports every time i doc, What would I be looking for on them? there is plenty of water coming out of the side of the boat when running,

My wake seems to be about the same, So normally when i would touch the throttle especially full throttle i believe i could feel the movement of the boat instantly, Now it seems i hear all motor then gradually start moving etc.. Its the weirdest thing.. Or am I just smoking something?
 

Bruce

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Forgive me for not knowing what Cavitation is?
Cavitation is where air bubbles form in the water running through the jet pump. It reduces efficiency and can cause wear to the impeller.

Cavitation occurs when something interferes with the flow of water. It could be as simple as seaweed caught in the intake, something wrapped around the shaft, something stuck between the impeller and pump housing or more expensive such as damaged impellers.

I suggest checking the pumps for anything that might be stuck in there. If that is not to solution post pictures of your impellers. You can reach a phone in through the intake grate to take pictures.

What is your GPS indicated top speed? You can use an app on your phone to check GPS speed. In 100% condition on smoothish water your top speed should be around 52.
 

Jmuir

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2001
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Where might the pumps be located? I have felt around the shaft and pulled some stuff off of them but still ran the same- if there are pitted, or small chips on the impellers can that effect it? I havent checked yet just asking,
 

Jmuir

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Also not sure if you or anyone has expierenced this or not but when pulling someone on the waterboard or just normal cruising ill have my throttles set not touch them and all of the sudden the motor starts to rev up and go faster? Without touching the throttle, Im hoping you have had the same issue and can direct in a fix.
 

Bruce

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The jet pumps start at the large intake grates under the boat and run all the way back to the steering nozzles.

Anything in the jet pump can cause cavitation reducing thrust and speed.

On the revving up issue, are the throttles moving without you touching them? If so they need to be adjusted. If not then I wonder if you have an issue with clogged carbs or fouled spark plugs.
 

Jmuir

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Yamaha
Year
2001
Boat Model
LS
Boat Length
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I thought that the water just went into the intake grates under the boat then the propellers spun and that was the power, Am i just 100% mistaken on that? Am i able to take intake grate off to see inside and look at the pump?

Is it bad to suck up sand or can it clog or do something?

On the revving up, The carbs, throttle etc they are very responsive with no lag- I replaced the plugs this spring- And NO the throttles are not moving without touching them.. We used to have to hold them cause they were loose but I fixed it so now we can set them and they will stick, but when they would move on their own they would go down not up.. So that would be the opposite of it all of the sudden just revving up without touching the throttle sticks..
 

Jmuir

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Also, thank you for all of the help I really appreciate it.
 

Bruce

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The pump is the impeller (internal propeller) and everything else from the intake grates to the steering nozzles.

You can get a look at the front of the impellers by sticking a phone or small camera up through the intake grate.

If you want a better look pull the pump

 

Jmuir

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2001
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LS
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Is it ok to have some pitting on the propellers? or will that cause cavitation? Is there way to take the intake grates off?
 

Bruce

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Is it ok to have some pitting on the propellers? or will that cause cavitation? Is there way to take the intake grates off?
The intake grates can be removed. It is possible that you would damage the fasteners and you certainly would need to replace some sealant. It is much easier to pull the pumps which allows you to see both sides of the impeller.

Pitting on the impellers will cause caviation.
 

4x15mph

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I would not take the intake grates off. You may want to pull off the pumps as a last resort and it definitely sounds like you have some cavitation going on.

I would solve this problem first. If you then have the problem with the sudden revving, I would say you might be having a "lean" condition where air is getting into the intake/fuel and causing this sudden RPM increase.... this is not good if this is the problem. One way of checking if it is a lean condition is to pull out the choke when it happens - if the rpm's come down, you probably have a lean condition/problem. Do not run the boat if this keeps happening since the cylinder can get hot and you run the risk of damaging the engine/cylinder(s). Very bad
 

Jmuir

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Boat Make
Yamaha
Year
2001
Boat Model
LS
Boat Length
21
What would be causing the lean condition? and how can you diagnose it? The revving only happens occasionally and when its at a certain speed around 16 to 20 mph when pulling a wakeboarder.

Does anyone have a place for cheap propellers or wear rings?

Is it recommended in replacing wear rings when replacing the propellers?
 

4x15mph

Jetboaters Admiral
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Location
Downingtown, PA
Boat Make
Yamaha
Year
2018
Boat Model
AR
Boat Length
21
SBT will recondition your impellers if you send them in or you can buy aftermarket solas impellars. You can also get new impeller housings that use replaceable wear rings. I did that when I rebuild my jet pumps (new impellers, wear rings, ducts, )

You could just be missing some silicone inside the pump area so check around before doing a rip and a replace.
 
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