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Loss of Power - SX240

jfahning

Member
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Location
Lake Minnetonka, MN
Boat Make
Yamaha
Year
2012
Boat Model
SX
Boat Length
24
I have 2012 SX240 with approximately 220 hours. Port engine running approximately 800 rpm less than starboard engine (tops out at 6800 rpm) and has limited power. Power difference noticeable between engines when in water and loss of hole shot evident.

Here is what has been done/checked:
~ New spark plugs changed and gapped
~ Gas treated and clean (have run greough a series of tanks this summer over the 80 hours put on already this season)
~ Ports cleaned and impeller pulled and checked for instructions.


Took to dealer and they hooked up to test equipment and nothing being seen out of the ordinary.

Stumped!! Thoughts or ideas?
 

djetok

Jetboaters Captain
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Location
Edmond, ok
Boat Make
Yamaha
Year
2015
Boat Model
SX
Boat Length
21
I have 2012 SX240 with approximately 220 hours. Port engine running approximately 800 rpm less than starboard engine (tops out at 6800 rpm) and has limited power. Power difference noticeable between engines when in water and loss of hole shot evident.

Here is what has been done/checked:
~ New spark plugs changed and gapped
~ Gas treated and clean (have run greough a series of tanks this summer over the 80 hours put on already this season)
~ Ports cleaned and impeller pulled and checked for instructions.


Took to dealer and they hooked up to test equipment and nothing being seen out of the ordinary.

Stumped!! Thoughts or ideas?
Check your pump for cavitation. Some good members to search for cavitation fixes , would be @swatski. Search cavitation and swatski. You will see the tunnel masters threads on cavitation.
 

Canuckjetboater

Jet Boat Addict
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Boat Make
Yamaha
Year
2020
Boat Model
SX195
Boat Length
19
Check your pump for cavitation. Some good members to search for cavitation fixes , would be @swatski. Search cavitation and swatski. You will see the tunnel masters threads on cavitation.
@djetok .....agree cavitation on a boat with 220 hours is a possibility. Check the impellers, wear rings and silicone around the plates. :cool:
 

jfahning

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Location
Lake Minnetonka, MN
Boat Make
Yamaha
Year
2012
Boat Model
SX
Boat Length
24
Taking out today to identify if any cavitation. Assuming this is the issue, and cavitation is present, bad to operate until fixed? May take a few weeks to get parts this day and age...
 

Scottintexas

Jetboaters Admiral
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Location
Corinth, TX (DFW)
Boat Make
Yamaha
Year
2007
Boat Model
AR
Boat Length
23
measure the distance between the impeller and the wear ring also check for loose silicone sealant in the "tunnel" area, pull on it with your fingers, it may look attached but actually be loose and the suction from the jet can pull it up allowing air in,

cavitation is always a hard one to diagnose as sometimes its the piece of fishing line you can't see, loose silicone somewhere, impeller gap or the debris that falls out when you load the boat on the trailer that no one sees and suddenly it's "fixed",

It's ok to run it as long as your not having any serious vibration issues, my boat rattled like it was about to throw the engine when I had a silicone issue.

just a wild guess but also thinking maybe fuel delivery, if you've got some debris stuck on your fuel pick up for that engine ??

Where are you at ? update your profile with your location,



.
 

jfahning

Member
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Location
Lake Minnetonka, MN
Boat Make
Yamaha
Year
2012
Boat Model
SX
Boat Length
24
Profile updated...
Sikicon was mentioned. Where would I need to look for that?

Also, “fuel pick up” was mentioned. Please clarify...

Thanks!!
 

Scottintexas

Jetboaters Admiral
Staff member
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Location
Corinth, TX (DFW)
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Yamaha
Year
2007
Boat Model
AR
Boat Length
23
silicone - when you pull your impellers look inside the jet housing and you can see the intake grate/tunnel pieces are attached to the hull with silicone/sealant, all those plates attached to the boat have a sealant to help keep air from being sucked into the jet, check all of it,

fuel pick up- this is the tube inside the gas tank, possible it could have some debris and when you apply throttle it causes enough interruption to the fuel flow that you can't get max rpm, (this would be a very unusual issue that we rarely see but when you have ruled out other things you start to have to look at the basics again and then at the unusual)

When was the last time it ran correctly ?


.
 

jfahning

Member
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Location
Lake Minnetonka, MN
Boat Make
Yamaha
Year
2012
Boat Model
SX
Boat Length
24
Noticed it about two weeks ago....had cleared some weeds and ran fine rest of evening. Put in the water a few days later and then noticed it.

Pulled impeller last weekend but nothing caught on impeller which is why I am stumped and looking at items before replace impeller and wear ring.
 

jfahning

Member
Messages
5
Reaction score
0
Points
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Location
Lake Minnetonka, MN
Boat Make
Yamaha
Year
2012
Boat Model
SX
Boat Length
24
measure the distance between the impeller and the wear ring also check for loose silicone sealant in the "tunnel" area, pull on it with your fingers, it may look attached but actually be loose and the suction from the jet can pull it up allowing air in,

cavitation is always a hard one to diagnose as sometimes its the piece of fishing line you can't see, loose silicone somewhere, impeller gap or the debris that falls out when you load the boat on the trailer that no one sees and suddenly it's "fixed",

It's ok to run it as long as your not having any serious vibration issues, my boat rattled like it was about to throw the engine when I had a silicone issue.

just a wild guess but also thinking maybe fuel delivery, if you've got some debris stuck on your fuel pick up for that engine ??

Where are you at ? update your profile with your location,



.
What should be the distance be between impeller and wear ring? Pulling impeller....
 
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