Engine stalls LS2000

[Big Daddy]

I took my jet boat out for its first run of the season last weekend after storing it for the winter. Boat started fine and ran great for hours... all at low speed. After dinner decided to take a long cruise before taking her home, again ran fine at higher speeds for approximately 45 mins, boat performed very well. Suddenly the port engine stalled while at approximately 3/4 throttle. It would start up fine and continue to run well at low speeds but as soon as I would accelerate to come up on plane... engine would run on plane for about 20 seconds and then stall. I continued to start the engine, bring the boat on plane for 20 seconds, have it stall, start again etc. over and over til we got back to our dock. Battery and plugs were brand new before this voyage and boat was winterized. Starboard engine continues to run fine. I did notice a small amount of oil in the bilge the following day and a compression test on the motor showed 2 cylinders reading 118 psi while the center cylinder read only 88 psi. Any thoughts or ideas on what to try next?? Thanks

 

[Bruce]

Until you got to the compression and oil on the floor part I was thinking that your carbs were clogged and SeaFoam might help you as it did me - https://jetboaters.net/threads/seafoam-worked-for-me.45/

Now that we get to oil on the floor and low compression on one cylinder my guess is that one or more of the oil injection hoses has failed and that center cylinder is burned up. If so you have options of rebuilding the engine yourself, sending it away for a rebuild, buying a used engine or buying a rebuilt engine.

@Speedling, I believe you rebuilt a similar engine.

 

[4x15mph]

Compression indicates an issue but are you sure your cleanout plug tray, safety switches are fully depressed? You can tape a quarter to the hatch above the switch to see if it gets better. You say this happens when you get up on plane so that is why I question those switches.

Oil in the bilge is concerning so before you run this make sure all oil lines are on tight and see if you can find the source of the oil leak. It could be grease from the intermediate bearing or starter since they can leak out of the nipple and resembles oil.

 

[DCB-270]

You can just replace that one cylinder but if the engine has some hours on it might as well do all 3. Not too hard of a job. I've done it several times. Also find the cause. Oil line off? I always took the oil injection off and pre mixed.

 

[Big Daddy]

I will try to find the cause of the oil leak in bilge. There was really not a lot of oil in the bilge. Also I will re-check the compression. Can you recommend a site that shows the proper way to replace a cylinder as the engines have less then 40 hours on them.

 

[Speedling]

1. Find source of oil because if an oil line came off then yes you could have a toast piston it could also be fuel/oil mix and if it is then something else may be broke.
2. If piston is fine and oil is all good my next thought was reeds and/or carb cleaning and tuning.
3. If the piston is bad it is very easy to replace but i will hace to dig for my source for the work i did. I know i had a maintenance book that i sent with my boat but sbt had a good writeup of removal as well.
I would get oversized pistons and bore it out slightly if you go that route to make your engine a real good freshening.
I will dig what i can but the 2 smokes are awesome easy

 

[skrip345]

You'll need a service manual. The oil lines are mounted to the air box on the underside, so you will have to inspect carefully. Completely a bad cylinder behavior though, definitely gonna have to tear down, and likely bore the cylinder, and replace piston, rings, pin, wristpin bearing and clips.

 

[Speedling]

https://www.shopsbt.com/pdfs/y11001200npv.pdf

 

[Speedling]

You'll need a service manual. The oil lines are mounted to the air box on the underside, so you will have to inspect carefully. Completely a bad cylinder behavior though, definitely gonna have to tear down, and likely bore the cylinder, and replace piston, rings, pin, wristpin bearing and clips.

Yeah, the service manual was worth it for sure.

 

[Big Daddy]

Thanks for the help!

 

[DCB-270]

You won't known how bad the damage is until you pull the head. Some time just hone the one and one piston and rings . used to be about 100 for piston and rings and you will need a gasket kit. At 88psi I think you caught it early.

 

[4x15mph]

@Big Daddy - pm me your email address if you want the service manual.

 

[Bbboater]

If anyone still has the service manual, can I get a link or copy, please?