2017 Yamaha Sh190 jet boat power issue.

[aj2910]

Hi all, I am new to this site but looking for help on a 2017 Sh190 Yamaha jet boat. My boat has been serviced each year by a local dealer but this summer the boat runs at 7200 rpm and a speed of 32 mph on the first run but quickly as the engine warms up cannot go over 6200 rpms and speeds drop to 20 mph, I can hardly pull a small child on a tube, with one other adult in the boat. the longer we run the boat the slower it goes. My boat dealer has been very little help.

I was thinking of starting by changing spark plugs but the were changed last December in have only about 20 hours on them.

Aj

 

[Neutron]

Try new plugs and check oil level

 

[ToddW850]

I read in another post the owner got his boat back from the dealer after service and his boat would not run over 6200 RPMs. The dealer had significantly over filled his oil. You may check that.

 

[aj2910]

Try new plugs and check oil level

Thanks, plugs only have 20 hrs , will double check oil level

 

[aj2910]

I read in another post the owner got his boat back from the dealer after service and his boat would not run over 6200 RPMs. The dealer had significantly over filled his oil. You may check that.

I will check oil and air filter next.

 

[Neutron]

Thanks, plugs only have 20 hrs , will double check oil level

Doesn't matter how many hours, for the price of them and how easy it is to replace, you replace them when you are experiencing issues. You could have one fouled plug causing this

 

[ToddW850]

Doesn't matter how many hours, for the price of them and how easy it is to replace, you replace them when you are experiencing issues. You could have one fouled plug causing this

Like the old Yamaha saying, if your trailer is making a funny noise, change the spark plugs in the boat and will probably fix it, haha

 

[aj2910]

Doesn't matter how many hours, for the price of them and how easy it is to replace, you replace them when you are experiencing issues. You could have one fouled plug causing this

Found oil in my air filter today. Took to dealer to determine why.

 

[Neutron]

O

Found oil in my air filter today. Took to dealer to determine why.

Il will only end up there if overfilled or you have excessive blow-by. How was the oil level?

 

[aj2910]

Well that is a good question, the cold oil level is at the top hole on the dip stick. I could not get an answer from the desk if that is the cold level or hot level.

 

[Neutron]

Well that is a good question, the cold oil level is at the top hole on the dip stick. I could not get an answer from the desk if that is the cold level or hot level.

You never checked it yourself?

 

[aj2910]

Yes that is where the oil level was before I checked the air filter. Once I pulled the air filter and found it was covered in oil I called the dealer. I did not want to put in the new filter until it was checked out. I did not want to mess up the new filter, it is very expensive.

 

[ToddW850]

Yes that is where the oil level was before I checked the air filter. Once I pulled the air filter and found it was covered in oil I called the dealer. I did not want to put in the new filter until it was checked out. I did not want to mess up the new filter, it is very expensive.

Sounds like you've found your issue.