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!

The Yamaha FX140 reportedly cuts emissions by 75 percent over carbureted two-stroke models of similar horsepower. According to the people at Yamaha, the four-stroke model more-than-meets Environmental Protection Agency emissions standards for 2006 and California Air Resources Board emissions standards for 2007.

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

Performance Kits - Yamaha Performance Kits - FX140 (MR-1 Engine) 2002-08. Sales & Support: 954-785-2684. Chem3d mac. Menu Nav; Shop All Categories. Les, the Canadian Swamp King, ran into a bit of trouble with his 2015 Yamaha SVHO FX Cruiser personal watercraft jetski when it suddenly quit on him.

• View and Download Yamaha 2004 WaveRunner FX140 owner's manual online. 2004 WaveRunner FX140 boat pdf manual download. Also for: Fx cruiser, 2004 waverunner fx cruiser.
• Shop our large selection of 2002 Yamaha FX140 (FX1000A) OEM Parts, original equipment manufacturer parts and more online or call at 908-483-5329.

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

Yamaha Fx 140 Engine Manual Transmissions

https://jetboaters.net/threads/ar230-engine-oil-question.17515/

Yamaha Fx 140 Engine Manual Diagram

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

Waverunner Fx 140

never run your boat on one engine or be towed faster than no wake speed (and put your throttles in fwd)

This page outlines the Color & Specifications of the FX Limited SVHO. Forex tester for mac download.

2003 Yamaha Fx 140

Available Colors	Black with Neon Lava
Length (m)	3.58
Width (m)	1.27
Height (m)	1.23
Dry Weight (kg)	373
Engine Type	Supercharged 4-cylinder, 4-stroke, Super Vortex High Output Yamaha Marine Engine
Displacement	1,812
Bore x Stroke (mm)	86 × 78
Compression Ratio	8.5 : 1
Cooling System	Water-Cooled
Pump Type	Φ160mm axial flow
Fuel Type Recommended	Premium Unleaded
Fuel Supply System	Electronic Fuel Injection
Fuel Capacity (liter)	70
Lubrication System	Wet Sump
Total Oil Capacity (liter)	5.3
Storage Capacity (liter)	166.7
Rider Capacity	1-3 persons

2002 Yamaha Fx 140

• Body and seat colors may differ from the actual models. In some cases, photos from other models may have been used. Please consult your nearest dealer before purchase.
• Please consult your nearest dealer for details regarding equipment and optional parts.
• Accessories shown in the photos are not included with these products.
• Product names, coloring and graphics may differ by country or area.
• Specifications are subject to change without notice.