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Known issues for boat years 2003-2009 with MR1 engines

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Scottintexas

Jetboaters Admiral
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Location
Corinth, TX (DFW)
Boat Make
Yamaha
Year
2007
Boat Model
AR
Boat Length
23
This post is about common issues with the “classic” style Yamaha jet boats, years 2003-2009 with four stroke MR1 (High output or non-HO) engines. These are great boats that were the transition from the 2-stroke rockets to the family run abouts. They have endured over the years and are still operating and retaining a high value but they did leave the factory or develop a few common issues that we have noticed over the years.


If you are looking at purchasing one of these classics, a new owner or a long time owner that just hasn’t noticed any issues these may be items worth taking a look at.


This post is not about user error items (damaged impellers, impeller bearings, gelcoat damage) or routine maintenance items (oil-spark plug changes) or common upgrades (steering fins, stereos, trailer guide posts). Look in the FAQ tab at the top of the page for many great upgrade DIY’s on those subjects and most of the common issue topics mentioned here.


This post is for reference only and locked, it is not the place for your question. If you have a problem you can’t fix please start a new thread and we can address it there. If you have an item you think should be added to this post please start a conversation (top right of this page) with me or an administrator/moderator. We are not certified marine mechanics or Yamaha corporate. If you notice an error or have a comment please let us know.


We hope you find this useful and remember this is a user run webpage without advertising or sponsorship. We are all just jet boat owners and this forum only works because users participate, stop in and say hello!


  1. Scupper valve – This is the cockpit drain that exits at the rear of the boat under the water line. It is a plastic fitting that many have reported cracked/leaking/broken. Worst case scenario is this fitting breaks on the inside of the boat creating a 2” hole below the water line. https://jetboaters.net/faq/#faq-223
  2. Loose throttles – The throttles will not stay at the RPM you place them but will slip causing a reduction in RPM. https://jetboaters.net/faq/#faq-24

  3. #3 spark plug being seized in head - We don’t know the exact reason why but many report this plug being seized and if so it’s easily broken causing you to have to remove the head to fix. Change your spark plugs regularly to help avoid this problem. https://jetboaters.net/faq/#faq-29

  4. Cleanout plug repair/locks – These plugs if not installed correctly or possibly even installed correctly can disengage and “blow” while under pressure. This can cause anything from just loss of thrust to at high pressure, the plug launching, breaking the engine hatch and going into the air or worst of all getting caught in the cleanout tube and turning sideways. This can detach the cleanout tube from the tray and when you apply more throttle to try to get thrust your actually pumping water into your bilge/engine area. This can turn very bad very fast. Some owners don’t ever remove their plugs causing sand/grit/debris to cement the plugs in the tube.

    You can add locks to prevent a blowout - https://jetboaters.net/faq/#faq-85

    You can rebuild your plugs to help with the removal process - how to rebuild your plugs or how to maintain your plugs per yamaha

  5. Floor rot – the table leg holder and t-handle latches have rubber gaskets around them. If not sealed tightly water can seep in and eventually cause the wood between the fiberglass to rot. https://jetboaters.net/faq/#faq-229

  6. Fuel sending unit – The gas gauge will often times either not show the correct level or no level at all. You can adjust the level markers on the sender or replace the entire unit. gas gauge not reading right or Fuel sender replacement
  7. manifolds crack/seeping – this is a relatively new item we heard about but any MR1 would be worth monitoring. https://jetboaters.net/threads/milky-foamy-oil-in-a-2008-ar210-with-825-hours.13994/page-2 or https://jetboaters.net/threads/2005-ar230-saga-continues-now-i-have-water-in-the-oil.10555/

  8. ECU/open injector dumping fuel into the oil - https://jetboaters.net/threads/help-engine-smoking-and-lack-of-power.7417/#navigation

  9. No wake mode not working – we have found the no wake feature is very sensitive to battery charge or the throttle stop,
  10. 2005-2006 models – The engine hatch step over drain can leak water into the ECU box causing issues. ???link??? How to remove the ECU
  11. 2007-2009 models – closet door trim will shrink fall off, leaves glue mess - how to replace

  12. 2007-2009 models – fuel hatch bolts, these are a uncommon size and many have found them with some sort of adhesive sealing them in. How to remove the bolts

  13. 2007-2009 models – gray diamond trim upholstery leather is poor quality and easily deteriorates

  14. 2007-2009 models – horn malfunctions - how to replace

  15. 2007-2009 models – windshield rubber molding shrinks. - How to replace
  16. 2008 - ??? – overheat caused by flashing not fully removed in cooling water connectors. How the water flows through the engine
  17. 2008 -??? Sirus radio feature will cause battery drain even in off position

  18. MFI trailer – The folding tongue can cause a loss of ground. You can add a jumper around it to fix it. https://jetboaters.net/threads/why-cant-i-get-a-ground-on-my-trailer.2568/#post-40778

  19. MFI trailer – Reverse lock out pin. If you only have a four pin hook up this feature allows you to back up or you can reverse to your connector, I suggest running a new 5 pin connector so you never have to leave your vehicle to back up. https://jetboaters.net/threads/loosing-your-trailer-lockout-key.742/

  20. MFI trailer – Loose bow stop- we’re not sure if it was engineered this way the bow stop can flex with the single bolt holding it at the bottom and speculation is that is the cause for a lot of scratches members have on boats from it moving while being trailered. Some have welded it in place while others have added a second bolt to secure it. How to fix
21. Cleat nuts loose - with the use of adhesive to the fuel cover why would they not use Loctite on the cleat nuts? many of us have loose
cleats and some even have found them completely off rolling around, these are large nuts and cleats are expensive if one drops off,
don't ignore a loose/wobbly cleat
https://jetboaters.net/threads/starboard-mid-cleat-did-you-know.10811/#post-207633

22. Engine compression - always good to get a compression test done especially if the boat has been sitting for years, water in the water box
can condensate up through the exhaust valves causing sticking valves and cylinder/ring issues
https://jetboaters.net/threads/ar230-engine-oil-question.17515/


Other important notes you can view in the FAQ;
Know what drowning looks like
Take a boater's safety course
Never run your engine without cooling water
If run the engine at home on hose use the method- engine on, water on, then water off, engine off
never run your boat on one engine or be towed faster than no wake speed (and put your throttles in fwd)
 
Last edited by a moderator:

Beachbummer

Jetboaters Captain
Messages
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Location
Houston TX
Boat Make
Yamaha
Year
2008
Boat Model
SX
Boat Length
23
I thought 8 and 10 were related. I had not heard of it happening on 07+ boats. Can you confirm? Thanks!
 

swatski

Jetboaters Fleet Admiral
Messages
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Reaction score
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Location
Saint Louis, MO
Boat Make
Yamaha
Year
2016
Boat Model
AR
Boat Length
24
This post is about common issues with the “classic” style Yamaha jet boats, years 2003-2009 with four stroke MR1 (High output or non-HO) engines. These are great boats that were the transition from the 2-stroke rockets to the family run abouts. They have endured over the years and are still operating and retaining a high value but they did leave the factory or develop a few common issues that we have noticed over the years.


If you are looking at purchasing one of these classics, a new owner or a long time owner that just hasn’t noticed any issues these may be items worth taking a look at.


This post is not about user error items (damaged impellers, impeller bearings, gelcoat damage) or routine maintenance items (oil-spark plug changes) or common upgrades (steering fins, stereos, trailer guide posts). Look in the FAQ tab at the top of the page for many great upgrade DIY’s on those subjects and most of the common issue topics mentioned here.


This post is for reference only and locked, it is not the place for your question. If you have a problem you can’t fix please start a new thread and we can address it there. If you have an item you think should be added to this post please start a conversation (top right of this page) with me or an administrator/moderator. We are not certified marine mechanics or Yamaha corporate. If you notice an error or have a comment please let us know.


We hope you find this useful and remember this is a user run webpage without advertising or sponsorship. We are all just jet boat owners and this forum only works because users participate, stop in and say hello!


  1. Scupper valve – This is the cockpit drain that exits at the rear of the boat under the water line. It is a plastic fitting that many have reported cracked/leaking/broken. Worst case scenario is this fitting breaks on the inside of the boat creating a 2” hole below the water line. https://jetboaters.net/faq/how-to-replace-a-broken-or-waiting-to-break-plastic-scupper.113/
  2. Loose throttles – The throttles will not stay at the RPM you place them but will slip causing a reduction in RPM. https://jetboaters.net/faq/how-to-stop-your-throttles-from-slipping-back-adjustments.44/

  3. #3 spark plug being seized in head - We don’t know the exact reason why but many report this plug being seized and if so it’s easily broken causing you to have to remove the head to fix. Change your spark plugs regularly to help avoid this problem. https://jetboaters.net/faq/i-sheared-off-a-spark-plug-when-changing-them-what-do-i-do.65/

  4. Cleanout plug repair/locks – These plugs if not installed correctly or possibly even installed correctly can disengage and “blow” while under pressure. This can cause anything from just loss of thrust to at high pressure, the plug launching, breaking the engine hatch and going into the air or worst of all getting caught in the cleanout tube and turning sideways. This can detach the cleanout tube from the tray and when you apply more throttle to try to get thrust your actually pumping water into your bilge/engine area. This can turn very bad very fast. Some owners don’t ever remove their plugs causing sand/grit/debris to cement the plugs in the tube.

    You can add locks to prevent a blowout - https://jetboaters.net/faq/how-to-prevent-your-cleanout-plugs-from-blowing-out-this-is-important.21/

    You can rebuild your plugs to help with the removal process - https://jetboaters.net/faq/clean-out-plug-repair-kit-aka-manhole-cover.22/ or https://jetboaters.net/faq/yamahas-bulletin-on-how-to-maintain-your-clean-out-plugs.114/

  5. Floor rot – the table leg holder and t-handle latches have rubber gaskets around them. If not sealed tightly water can seep in and eventually cause the wood between the fiberglass to rot. https://jetboaters.net/faq/how-to-repair-fiberglass-fix-wood-rot-underneath.136/

  6. Fuel sending unit – The gas gauge will often times either not show the correct level or no level at all. You can adjust the level markers on the sender or replace the entire unit. https://jetboaters.net/faq/my-gas-guage-doesnt-read-right-how-to-fix.95/ or https://jetboaters.net/faq/gas-guage-fuel-sender.96/

  7. manifolds crack/seeping – this is a relatively new item we heard about but any MR1 would be worth monitoring. https://jetboaters.net/threads/milky-foamy-oil-in-a-2008-ar210-with-825-hours.13994/page-2 or https://jetboaters.net/threads/2005-ar230-saga-continues-now-i-have-water-in-the-oil.10555/

  8. ECU/open injector dumping fuel into the oil - https://jetboaters.net/threads/help-engine-smoking-and-lack-of-power.7417/#navigation

  9. No wake mode not working – we have found the no wake feature is very sensitive to battery charge or the throttle stop, https://jetboaters.net/faq/no-wake-mode-not-working-on-my-yamaha.102/

  10. 2005-2006 models – The engine hatch step over drain can leak water into the ECU box causing issues. ???link???

  11. 2007-2009 models – closet door trim will shrink fall off, leaves glue mess https://jetboaters.net/faq/how-to-replace-old-sticky-gooey-trim-on-the-door-opening.125/

  12. 2007-2009 models – fuel hatch bolts, these are a uncommon size and many have found them with some sort of adhesive sealing them in. https://jetboaters.net/faq/how-to-remove-the-floor-to-access-the-fuel-tank-07-09-yamaha-boats.119/

  13. 2007-2009 models – gray diamond trim upholstery leather is poor quality and easily deteriorates

  14. 2007-2009 models – horn malfunctions https://jetboaters.net/faq/how-to-replace-your-horn.46/

  15. 2007-2009 models – windshield rubber molding shrinks. https://jetboaters.net/faq/windshield-rubber-trim.163/

  16. 2008 - ??? – overheat caused by flashing not fully removed in cooling water connectors. https://jetboaters.net/faq/how-does-the-water-actually-flow-through-my-yamaha-engine.75/

  17. 2008 -??? Sirus radio feature will cause battery drain even in off position

  18. MFI trailer – The folding tongue can cause a loss of ground. You can add a jumper around it to fix it. https://jetboaters.net/threads/why-cant-i-get-a-ground-on-my-trailer.2568/#post-40778

  19. MFI trailer – Reverse lock out pin. If you only have a four pin hook up this feature allows you to back up or you can reverse to your connector, I suggest running a new 5 pin connector so you never have to leave your vehicle to back up. https://jetboaters.net/threads/loosing-your-trailer-lockout-key.742/

  20. MFI trailer – Loose bow stop- we’re not sure if it was engineered this way the bow stop can flex with the single bolt holding it at the bottom and speculation is that is the cause for a lot of scratches members have on boats from it moving while being trailered. Some have welded it in place while others have added a second bolt to secure it. https://jetboaters.net/faq/my-bow-stop-is-loose-how-do-i-fix-it.78/
Other important notes you can view in the FAQ;
Know what drowning looks like
Take a boater's safety course
Never run your engine without cooling water
If run the engine at home on hose use the method- engine on, water on, then water off, engine off
never run your boat on one engine or be towed faster than no wake speed (and put your throttles in fwd)
Wow, this is just an awesome compilation, very useful!

But - how would you put one together for the current models? It would be a novel...

(Note to self: should have bought one of the late model 230s... bullet-proof!)

--
 
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