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Acceleration slow on a 04 Sportster 4-tec.. please help!!!

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jombie

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Engine is running fine. RPMs, coolant, oil, everything sounds good but I dont get the acceleration I used to have. It now takes a what feels like a minute or two to plane.
Could really use some help trouble shooting this now I'm on an island with no dealer option to go to. I tried searching the forums and have a few ideas but would really like to know if I'm "barking up the right tree" so to speak.

Had this boat in Fresh water since I got it in 04. Had Sea Doo techs give it a look over in '09 and had the boat repair shop based out of the Marina I stored it in do some reg. maintenance (replace fluids etc). last year. Had the whole thing shipped 3000 miles to the VI and just had it in the salt water for the first time yesterday.

Everything is working great except it barely gets out of its own way and takes forever to get up to speed despite the engine at full throttle.

Is there seals I should check out? and if someone can point me to Assy Drawings with part numbers I would greatly appreciate it!!!!

EDIT** Ok found some Exploded View Assy drawings on the parts site. Anyone have any suggestions on what to start looking for....like wear and tear on certain seals??? Thanks!

Weather is too nice down here to not be on the water!!!


Thanks!!!
 
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Don't be afraid to take it apart! I have a 2003 Sportster 155hp and just got it apart to replace the impeller and wear ring.
15 minutes to get the pump off. Took it to the Seadoo mechanic here in town and he removed the impeller for me for free.
(Didn't have impeller tool). Since looking on here, I see I may only need an allen wrench to hold the shaft. Still, seems to be
an easy fix. Another member here pointed me to SBT for replacement impeller and wear ring. Very inexpensive! Good luck.
 
Wait

Before you start pulling apart your pump here's a very simple technique to visually check for damage. Depending on how agile you are you may need two people to do this.

Get a really powerful torch. Climb underneath the boat when it's on the trailer and with one arm, shine the torch i.e. point it up into the intake grate and angle back towards the motor. Whilst you're doing that, stick your head into the back of the pump and have a look inside.

The light from he torch will come through from the intake grate and shine between the gap between your impellor and the wear ring. Any damage will quickly become obvious i.e. a large uneven gaps or chunks missing from the impellor will be visible. Remember it only takes a small ding or gap to cause severe cavitation.

I'd also then take the torch and look in from the rear and check the smoothness of the wear ring. Again any scratches / ruts will cause trouble.

Any signs of uneven surfaces and your next step is pump / impellor removal. Don't drive your boat if its cavitating. I have been warned that it can cause engine damage and further pump unit damage.
 
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Macster, Can you please give a detailed description of what cavitation is and what it means in terms of engine damage or pump damage? Does anyone have a picture of what a cavitated assembly looks like?
 
how about the guy who lit a match to see inside the gas tank?
He doesn't have to look anymore, the insurance company took care of the funereal expenses.

Ok, I'm only kidding but I bet somewhere,somehow, someone probably did this.
 
khangoroo said:
Macster, Can you please give a detailed description of what cavitation is and what it means in terms of engine damage or pump damage? Does anyone have a picture of what a cavitated assembly looks like?
Click to expand...

Let me explain it for ya. The basic concept of jet boats is jet propulsion. Normal prop boats use an external prop to push the boat along. Jet boats use an internal impeller. Think of it like a big fan blade. It sucks water up through the bottom of the boat through an intake and pushes it out the back through a smaller opening, creating force and moving the boat. That is the basic concept. When there is a restriction to the water flow, this thrust is greatly reduced. If there is a leak anywhere on the outlet side of the impeller, you get less thrust. The impeller is encased by a wear ring. The wear ring is like a plastic tube around the impeller. If you suck debris like sticks and rocks up, the wear ring is designed to get grooves in it and do exactly that...wear. Those excessive grooves now allow water to be pushed through the grooves instead of pushed out the pump by the impeller.


There isnt a specific picture. Lots of things cause cavitation. The majority of the time people are talking about excessive clearance in the wear ring. The plastic wear ring gets grooves in it that keep the impeller from being able to adequately push the water through without injecting air.
 
Thanks for the explanation JFoster. I'm not sure I understand why cavitation would cause engine damage then, other than it decreasing the ability of the impeller to push water and thus lower performance.
 
I think the previous post summed up cavitation. It feels like a slipping clutch in a car or like you're doing a burnout. Cavitation can eventually damage your prop as it actually boils the water and can take chunks out of your impellor edge. My Kawasaki prop had burn marks all over it and chunks falling off before I finally replaced it!

As for engine damage - I never quizzed the mechanic any further on this one at the time. I'm guessing that because the RPMs go through the roof when you cavitate, that it might not be good for the engine, in particular, the supercharger i.e. it wasn't good for the supercharger to rev out with no load.
 
khangoroo said:
Thanks for the explanation JFoster. I'm not sure I understand why cavitation would cause engine damage then, other than it decreasing the ability of the impeller to push water and thus lower performance.
Click to expand...

It doesnt cause engine damage. I dont know anyone who has stated it does. Even if the engine just revved up, the rev limiter would stop it from going too high. I would think people are smart enough to not sit and let it stay at max RPM while sitting there not going anywhere.
 
Ok believe it or not it's taken me this long to work on the boat. It took 2 months just to get the part down here from the states.
I work on other boats for a living and have been crazy busy this winter but now that the waters down here are nice and flat I'm ready to get the lil sea doo out.

Here's a pic of my 4-tec impeller.
The wear ring is... well... worn. lot's of grooves in it.
sea-doo-jet-pump.jpg
My questions is the impeller. There doesnt look like a ton of damage to it. 1 leading edge is a lil bit worn but other than needing to be cleaned up it looks good to me.

Any reason why I should pop this guy out? The bearing assembly is great. Checked the grease and it's nice and honey colored and still packed in good. No visible play in the bearings.

I'm going to try the freezer method to get the wear ring out.
It took 3 months to get the wear ring. dont want to wait another 3 for the spline tool if i dont have too!

Thanks
 
The impeller looks good. The groove in the ring is the problem. A new ring should have you fixed up.
 
Great!
I plan on putting it back together next day off work.

Thanks I can't wait to get it back in the water!
 
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