Where's the speed?

[Tom Duignan]

If 6,000 RPMS is the max RPM of one engine then spark plugs are a likely culprit on that engine.

But I also agree that having been in salt water all season that boat likely has a jungle growing below the waterline including in the jet pumps.

Thank You, I'm taking boat out tomorrow to take an expedition through the "jungle". I think you are correct and I'll let you know.
Thank You so much!
Tom

 

[Tom Duignan]

If 6,000 RPMS is the max RPM of one engine then spark plugs are a likely culprit on that engine.

But I also agree that having been in salt water all season that boat likely has a jungle growing below the waterline including in the jet pumps.

Thank You, Taking it out tomorrow, I'm sure you are correct and I'll see quite a bit of growth. Thank you so much,
Tom

 

[Tom Duignan]

Like CJS said, if it has been sitting in salt water for some time, guaranteed you have stuff growing in the pumps. That will have a massive impact on the efficiency of the pumps. 6k rpm also sounds like you need to replace spark plugs. I hate to say it but these boats are simply not suitable for leaving floating in salt water for extended periods (like a boating season).

Well, all of you people were correct. We removed the boat from the great south bay on Long Island and the entire hull was covered in barnacles. They were on and inside the jet pumps and the tunnel where the jet pumps sit. Two days of scraping and soaking with muriatic acid and "On and Off" hull cleaning made a big difference but still have the circles where the barnacles were. I guess those barnacles were causing cavitation. We're going to sand them down and test drive then, remove again and bottom paint if everything is OK. Still working on the jet pumps.
I'm still wondering if this situation had an impact on why the check engine lights were on.
Thank you and thank you all! I really appreciate all of your help.
Tom

 

[Bruce]

Yamaha boats do not have water pumps. The jet pumps force water through a filtered intake on the sides of the jet pumps.

Cavitation reduces the amount of cooling follow. Additionally the filters are likely clogged. I also worry that you may have growth inside the engines which would be an even bigger issue.

 

[Cobra Jet Steering LLC]

Agreed if you let the engines sit with salt water in them there will be a lot of growth in the water passages inside the block . There are lots of critters in that water.

 

[OrangeTJ]

I do not want to sound negative and I hate to be the bearer of bad news, but these boats really aren't made to be left sitting in salt water. I don't think there is really any reliable way to keep marine growth from happening inside the pumps and the cooling water passages that are open to them. Is it possible to have a lift at your slip? If not, you might want to give consideration to either trailering your boat (I know...not nearly as convenient as being in a slip) or trading for a boat more suitable for that environment.

 

[Tom Duignan]

Yamaha boats do not have water pumps. The jet pumps force water through a filtered intake on the sides of the jet pumps.

Cavitation reduces the amount of cooling follow. Additionally the filters are likely clogged. I also worry that you may have growth inside the engines which would be an even bigger issue.

Yes, you guys may be correct however, when I removed thermostats last week there was no growth in the hoses. While the boat wasn't being used we ran the engines every week and flushed with fresh water. Hopefully if anything was trying to grow in there it was flushed out with fresh water. The day we took it out of the water last week, we ran it for an hour first to see if removing thermostats resolved the overheating problem and there was no overheating issue at all. Couldn't go fast but, no overheating. Tomorrow I'm reassembling and re-installing jet pumps and shooting for test drive on Saturday. I used every chemical I could think of for the circles that the barnacles left on the hull after scraping off the barnacles themselves, (Muriatic acid, LCR and Marykate On/Off). Nothing worked so I'm gonna buff them off the hull and bottom paint the hull. Next year we have to remove the boat once a month and power wash or just trailer it.
Thank You All Again, I'll let you know how it works out,
Tom

 

[Cobra Jet Steering LLC]

If you looked in the water jackets with the thermostats removed and it did not look like you had growth the water jackets, the most probable reason your engines were running hot is due to the growth in your pump restricting the water flow to your engines. The pump sends water to the exhaust manifold and water box as well as the engine block so it is important to insure the water line from the pump is clear of obstructions also.
Once you cleaned the pumps and the block on the side of the pump where the water flows to the engine you are probably back in business.
You can check your thermostats by placing them in a pan of water with a cooking thermometer and heat the water while you watch for those to open, If they open properly they are ok. If you return them to the engines they should work fine, regulating the proper temperature is important for proper fuel efficiency and for performance So it is best to use the correct thermostats .

 

[Tom Duignan]

If you looked in the water jackets with the thermostats removed and it did not look like you had growth the water jackets, the most probable reason your engines were running hot is due to the growth in your pump restricting the water flow to your engines. The pump sends water to the exhaust manifold and water box as well as the engine block so it is important to insure the water line from the pump is clear of obstructions also.
Once you cleaned the pumps and the block on the side of the pump where the water flows to the engine you are probably back in business.
You can check your thermostats by placing them in a pan of water with a cooking thermometer and heat the water while you watch for those to open, If they open properly they are ok. If you return them to the engines they should work fine, regulating the proper temperature is important for proper fuel efficiency and for performance So it is best to use the correct thermostats .

Thank You so much. I'll check that area also. After we scraped all the barnacles off I sanded the hull and assembled the jet pumps after cleaning them out. We launched the boat this afternoon and got it up to thirty MPH on a choppy Great South Bay. Still got a check engine light on the port engine. Took the boat out again so I could bottom paint it. While I have it out I'm going to change the plugs. Going to take your advice again and install new thermostats. I couldn't get barnacles off the area above the ramps but, I will. I'm sure with the entire hull cleaned and painted and the new plugs and thermostats, I'll have it up to 35 Mph! That's good enough for me.
Thank You again for all your help and thank you all. This is a great forum!!
Tom

 

[Cobra Jet Steering LLC]

One more thing that came to mind is if your speedometer has the paddle wheel and that is dirty or binding up at all from growth you will get a bad reading for your top speed so if you have that system be sure the wheel is spinning freely and easily .

 

[Tom Duignan]

One more thing that came to mind is if your speedometer has the paddle wheel and that is dirty or binding up at all from growth you will get a bad reading for your top speed so if you have that system be sure the wheel is spinning freely and easily .

Thank You for thinking of me again. At the stern there is no type of wheel, it looks like a simple pointy plastic rod about three inches long. I thought that was the speedometer sensor but it doesn't move at all.
Thanks, Tom

 

[Cobra Jet Steering LLC]

Ok I was not sure what type of speedo you have, if the part has a tube attached then you probably have trash growing inside the tube , that type works off water pressure forcing air up to the speedo to indicate speed. Also that type of speedo is the least accurate.

 

[Tom Duignan]

Ok I was not sure what type of speedo you have, if the part has a tube attached then you probably have trash growing inside the tube , that type works off water pressure forcing air up to the speedo to indicate speed. Also that type of speedo is the least accurate.

No, didn't look like any type of tube there. It was just a pointy plastic piece and it didn't move as I thought it would as the boat moved over water. Just don't know what it does. It's at the stern on the starboard side. Transducer is on the port side.
Gonna look at it more carefully tomorrow when I bottom paint the hull.
Tom

 

[Cobra Jet Steering LLC]

Ok the confusion is that you list a 2010 sx 230 but there does not appear to be such an animal what are the last 2 digits of the hull number 09 was the last year for a sx230

 

[Cobra Jet Steering LLC]

On a 09 they use a plastic pickup at the rear of the boat with the tube running up to the speedo so any obstructions or critters in the tube will effect the speed reading.

 

[Tom Duignan]

Ok the confusion is that you list a 2010 sx 230 but there does not appear to be such an animal what are the last 2 digits of the hull number 09 was the last year for a sx230

No, the boat is a 2010 sx210
Tom

 

[Cobra Jet Steering LLC]

ok that uses the same pickup and tube as the 99