96 Seadoo Sportster wont run when in the water

[blh71]

I just bought a 1996 seadoo sportster that is suppose to have a new motor with only about ten hours on it. It starts up fine on the trailer with and without the water hose connected, but once it is backed down into the water the motor boggs down and there is no throttle what so ever and eventually dies, take it out of the water and seems to run fine. I put new spark plugs, and has a brand new battery in it. I have read a lot of threads and now I am confused and could use some advise.

 

[Dr Honda]

Sounds like the engine is dead.

What you are describing is very low compression. Do a compression test, and let us know what you find. (150 is good, 135 psi it should run)

 

[MerrillXP]

Check the water pressure regulator...

 

[blh71]

Man I hope you are wrong. I will check it tomorrow and post what I find.

 

[blh71]

water pressure regulator

What and where is the water pressure regulator

 

[Dr Honda]

Check the water pressure regulator...

He doesn't have one.

Man I hope you are wrong. I will check it tomorrow and post what I find.

I'll check back tomorrow.

 

[blh71]

Thanks DR. Honda, wasn't sure what the pressure regulator was. I have been through the owners manual several times and looked at parts schematics on the seadoo website and never seen that part. I am going to the parts store today to by a pressure gauge and I will post the pressures this evening.

 

[blh71]

I did forget to mention that once the boat is in the water and I start it I can move the throttle wide open and it doesn't do anything but try to stall, I can pull the choke out and it will run a little longer but nothing really above idle. Out of the water the throttle revs up.

 

[blh71]

I did a compression check and I was getting 120 on both cylinders, I think I bought a cheap gauge because depending on how I held it I could hear the air leaking so I am not sure that the 120 is 100% accurate. If it is correct does this mean I need a top end rebuild? Is this the problem?

 

[Dr Honda]

120 is low on a Rotax engine. If you think the gauge is bad, cheap... or just reading wrong... test it with an air compressor, or stick it in an engine that is running well.

I would find the air leaks on the gauge, and try to seal them.


Also, when you check the comression... the throttle should be open, but do not put any extra oil in the cylinders.

Fix the leaks, and check it again.

 

[blh71]

Ok I went back read the directions that came with my compression gauge, not sure why this makes a difference but it said to have the throttle wide open when testing. I tightened up the fittings on my gauge and opened the throttle wide open and after testing again I got 138 on both cylinders. Now what???? I appreciate the help, these forums are great.

 

[blh71]

I found a certified Seadoo mechanic on craigslist that does work on the side and I am dropping it off to him this evening. He is going to go through the carburators and then go from there. I will post the results once I know something new. I appreciate the help Dr. Honda.

 

[Dr Honda]

I found a certified Seadoo mechanic on craigslist that does work on the side and I am dropping it off to him this evening. He is going to go through the carburators and then go from there. I will post the results once I know something new. I appreciate the help Dr. Honda.

Before you pay someone to rebuild the carbs... have him check the compression. If he's a mechanic he should have a gauge he trusts. I had this very same thing happen at my shop 3 weeks ago. A member drove from Ohio with a "Fuel Supply" problem. I figured I would be a nice guy and just help him out since he was going to drive for 3 hours to see me. Once he got to my shop... I pulled the plugs to see what kind of fuel we were getting... and they were black and dripping. So, out comes the compression gauge, and sure enough... low compression. (I wound up doing and engine for him)


If you take it to him... and he gets 120 also... then don't spend the $$$ on the carbs since it won't help.

 

[blh71]

I already droppexd it off to the mechanic. I was pretty confident with my 138 pressure reading after I tightened everything up and followed the directions. I will give him a call today though to see what reading he got and post what he finds on here.

 

[Dr Honda]

If you got 138... its warn, but you are in the running range. Let us know what he finds.

 

[blh71]

The mechanic called me this evening and he got 140 on the compression which isn't bad. What he did find was something to do with the rotary timing, I think he said it was off 25 degrees and he was confident that this was my problem. I might be able to get it back as soon as tomorrow evening. Thanks again for the helpful posts. Please share your thoughts.

 

[pcmandevon]

That sounds wierd, somebody must have been in there for it to be that far off. Hope that was all that was wrong. Good luck, Devon.

 

[blh71]

new problem

Got the boat back yesterday evening and the mechanic said my rotary valve was off by 25 degrees. He also went through the carbs and cleaned those. I went straight to the lake after picking it up. It runs and sounds good, idles good, but when you are going along at full throttle and make a hard turn either way the motor will lose power. Is this a carb issue or the result of a lot of pressure on the impellar bogging the motor down? Any ideas?