2004 twin engine Yamaha SX230 in water will not shift into forward.

[Johnny Yuma]

Hi. We recently purchased this Yamaha Jet Boat (SX230 2004 twin 140hp engines) It had never been in salt water and had about 500 hrs on engines. Maintained by Yamaha mechanic stored indoors. Was in perfect condition. Worked great. I bottom painted it, put in salt water as of 6/1/25 and used it three times (no problems other than those inherent in switching from always driving a prop boat to a twin jet.) Yesterday my wife and I tried to use it. Both engines started fine. Untied from our dock. Would not shift into forward (or reverse) Engine revved but boat did not actually move (other than forward creep that as I understand it, jet boats always have). Shifter seems to be fine. I cleaned out twin clean out ports and made sure they were locked down. nada. Got back to dock. Wife not pleased. I have a Coast Guard Launch Op License and have been running boats for 55 years, so not a newbe. Never had a jet though. I live on an Island in Maine. Can't pull boat. No Mechanic available.
Sort of a worst case scenario. Help.

 

[anmut]

Could be a couple of things:

Your reverse buckets were not moving up. If you can, have someone move the throttles while the engine is off and visually confirm that they're moving up and down.

You stated you cleaned out your ports - what did you find? Junk in your pump tunnel and around your impeller will cause cavitation in your pump and give you this exact symptom. If you can, pull the boat out of the water and put your phone up between the intake grates and snap some photos of the impellers. You can also remove the impellers from the pump assembly (YouTube is your friend) - might seem like a big deal but it's really not. That will give you the cleanest inspection of them.

 

[Johnny Yuma]

Could be a couple of things:

Your reverse buckets were not moving up. If you can, have someone move the throttles while the engine is off and visually confirm that they're moving up and down.

You stated you cleaned out your ports - what did you find? Junk in your pump tunnel and around your impeller will cause cavitation in your pump and give you this exact symptom. If you can, pull the boat out of the water and put your phone up between the intake grates and snap some photos of the impellers. You can also remove the impellers from the pump assembly (YouTube is your friend) - might seem like a big deal but it's really not. That will give you the cleanest inspection of them.

Anmut, thanks so much for the quick reply. First suggestion-can do. Second- not so much. Boat ramp is 10 miles away on other side of island. Am reluctant to get in water with great whites nearby, so sort of limited to what I can do/reach from in boat or dockside. When I cleaned out the ports I pulled out fair amount of seaweed and small sticks. Also worried about growth of barnacles and sea crap on underwater engine parts. I bottom painted the hull but did not put anything on the metal of the engine. Was that a mistake? It's been in the water for two months now. I live where a river empties into the Gulf of Maine. So salt water and all the debris from rivers plus all the stuff from the ocean.

 

[anmut]

Here's a question - are you sure you reinstalled the locking devices on the cleanout ports? If those are out, or if they're not locked in tight, you'll get the same issue.

 

[Johnny Yuma]

That locking device worries me. It has 2 movable parts; One that you pull after pushing in the smaller button to release the hatch (to remove and clean out). To replace, you put it back in (same orientation) and push down on the larger handle. The small button pops up and the bolts on either side flare out. The problem is that despite it looking like a bank vault it can be removed easily without unlocking. This has confused me but as I said I'm new to this Jet Boat stuff.

 

[anmut]

If you can pull it out without unlocking, bingo, you found your issue. They make a rebuild kit for those plugs. Contact Will at JetBoatPilot

 

[Johnny Yuma]

Anmut, Please forgive. Brevity has never been a strength. Just got back from boat, taking several of your suggestions to try. (Its low tide and so boat is about 85' below house. I'm old and fat so climb back up not fun). Good news: both reverse diverters (?) were stuck in down position underwater due to barnacle and marine growth. I manually lifted them back up (after cleaning off as much as I could reach with a wire brush. Did I mention that it had now started to rain?) Both engines now shift from neutral to forward. (Judging by wash from engines. Did not want to push my luck and rip boat off float.) So that's really good. The cleaning hatches are secure and locked.

Here is/are my dilemma(s): (though an order of magnitude less than not being able to go forward)
A. I did not dare to try putting it in reverse. Will this happen again? Is my shifter mechanical or electrical?
B. Are Jet Boats just not a good idea in the salt water and with seaweed and crap all over the place?
C. For the future besides replacing the sacrificial anodes (duhh) is there some product that I can use on the underwater parts of the engine to retard barnacle and weed growth? The barnacles are growing, and the wire brush gets the seaweed but not the barnacles.

 

[Neutron]

Any jetboat is not ideal for extended stays in salt water, you will continue to have all sort of problems. And in the end when you try to sell it you will be pretty much giving it away for free.
My advice would be to pull the boat out clean all growth off and sell it. Buy a boat with a Yamaha outboard. It can be raised out of the water to prevent growth

 

[anmut]

Anmut, Please forgive. Brevity has never been a strength. Just got back from boat, taking several of your suggestions to try. (Its low tide and so boat is about 85' below house. I'm old and fat so climb back up not fun). Good news: both reverse diverters (?) were stuck in down position underwater due to barnacle and marine growth. I manually lifted them back up (after cleaning off as much as I could reach with a wire brush. Did I mention that it had now started to rain?) Both engines now shift from neutral to forward. (Judging by wash from engines. Did not want to push my luck and rip boat off float.) So that's really good. The cleaning hatches are secure and locked.

Here is/are my dilemma(s): (though an order of magnitude less than not being able to go forward)
A. I did not dare to try putting it in reverse. Will this happen again? Is my shifter mechanical or electrical?
B. Are Jet Boats just not a good idea in the salt water and with seaweed and crap all over the place?
C. For the future besides replacing the sacrificial anodes (duhh) is there some product that I can use on the underwater parts of the engine to retard barnacle and weed growth? The barnacles are growing, and the wire brush gets the seaweed but not the barnacles.

Well that's awesome that you figured out your issue!

Going forward, invest in a couple of cans of YamaShield protection spray. If you can, put the boat on the trailer for a few days so you can clean, and then spray down, everything on the pump. Let it dry. In fact, since you're on saltwater, I'd spray YamaShield on everything - motor, electrical connections, etc. Then just keep up with treatments.

As @Johnny Yuma stated, wet slipping jet boats is pretty hard on them. If you install a lift, that would be much better. Just keep up on your preventive maintenance.

https://www.amazon.com/Yamalube-Yamashield-Moisture-Displacing-Lubricant-ACC-YAMSH-LD-00/dp/B008KYTZQ8?gQT=3