900 zxi under 20mph

[westladog]

The last time this jet ski was on the water, my in-laws got the entire vessel submerged. I was able to drain the water out and got it started again.

Today I took it out to the lake, and it ran niserably. It has no problem starting.
Once I crack the throttle, it would bog (sometimes it would die). I would be able to get it restarted though. If I steadily increase the throtlle, it would go but it felt like the power was at less than 50%. I changed the spark plugs but still the same problem. Once in a while, it would pick up speed though for about a minute or so.

I don't know what could be the problem. Seizing cylinder(s)?
I didn't know to check if one of the cylinders is cooler than the others. I read this on some other posts.

How do I go about checking if the problem is due to the motor or the carbs?
Out of water, it cold rev all the way to redline of 8k. On the water, most of the time it can't go past 4500 rpm. Once in a while it would go past 5k rpm though. I remember initially on the water I was able to go past 7k rpm but there was no power though. The most it could go was around 20-25 mphs....
Typically, I can go to about 40mph easily.
This is a 95-96 900 zxi.

Any help is appreciated.

Also, what are the signs of a piston seizing?

[Dan750SX]

Re: 900 zxi under 20mph

While you wait for somebody more qualified to reply, here's my take.

Disgustingly simple things first...

One simple thing that comes to mind is to check and see if anything is lodged in the pump somewhere. I recall that my machine would bog if I got chunks of wood stuck in my pump.

Perhaps water got into the gas. Try draining the tank and filling it with fresh fuel.

If you haven't checked out SBT's video on submerged engines, check it out here:

http://www.sbtontheweb.com/forum/showthread.php?t=12031

You will want to try that as you may have water still in the engine.

If that doesn't work, some others could probably suggest some things to try. But it sems that if it isn't working after this step, a tear-down may be in order. It's the only way to see if the piston rings are messed up, if bearings are seized, if rods are bent, or if gaskets are blown.

I hope this helps!

[westladog]

Re: 900 zxi under 20mph

Pump? What pump? (Sorry...I'm kinda new at this)
So what's the correct way to drain the gas?

Also, with today's newer 4stroke watercraft with their car-like valve trains and stuff, what would happen to these 4stroke jet skis when submerged under water?

[Dan750SX]

Re: 900 zxi under 20mph

Pump - the jet pump. On the bottom of the hull of your boat is the intake. Look up there with a flashlight and see if there is any junk up there.

To remove gas, you can get a hand pump from an auto parts store that will pump out fluids.

I'm not familiar with 4 stroke operation, so I don't know how they react to water. But it can't be good.

[westladog]

Re: 900 zxi under 20mph

I spoke to a service guy at a dealer today regadrig this problem.
She said that it's most likely the problem is a reed valve problem. He was very certain it was casused my the jet ski being submerged. This caused the reed valve to go bad.

What do you guys think?

[WATERCRAFTSERVICES]

Re: 900 zxi under 20mph

Very common. Reeds break very often after water injestion if the engine is cranked with water still inside. Pull the manifold and check the reeds.

[Dan750SX]

Re: 900 zxi under 20mph

4 stroke motors have reed valves? Unless watercraft 4-strokes are different from the norm, the valves are in the cylinder head. It would be strange if they were still called reeds. But anyway, I could see how these could get damaged if water was in the motor.

I've never worked on a 4-stroke, so I couldn't begin to describe how to go about checking those. See if you can get a shop manual for your boat.

Good luck!

[Technical Support]

Re: 900 zxi under 20mph

The response about reeds was to the original question.


To answer the other, when 4's get ingested, if they are running at the time all hell breaks loose. Valves bend/hit, pistons shatter, heads blow/crack, cranks rust...not pretty. The cores we have need a LOT of work, and water is by far the number 1 killer of 4's so far.