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My 250 Yamaha fuel injected motor has lost 800 to 1000 RPM's at full throttle. No changes were made to the weight, distribution, or type fuel. The in-line fuel filter, gas filter, and plugs have been changed with no effect. It runs smoothly, but acts like it is governed at 5000 RPM's. Any ideas?
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I am do not a definative answer for you but am experiencing the same problem with 2001, 225 VMAX. It has been suggested to change/clean 02 sensor and change/clean fuel filter. Others have reported success, however, did not cure my problem. It has also been suggested to run a compression check. Will try this next. I am curious, do you have a weird knocking sound, somwhat like a choo-choo sound? My motor is making that sound and am wondering if sound can be associated with loss in RPM's.
Good luck!
Garry -
Bret,
There is a filter inside the vapor separator tank (VST) that may need to be cleaned.
The procedure for doing this is outlined in previous posts - I don't know it exactly since my motor is carbed.
I'm sure the procedure is spelled out in the Yamaha shop manual.
Also, if your motor has an O2 sensor, it needs to be cleaned on a regular basis.
Good luck [img]smile.gif[/img] ,
Ken KComment
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the sensor needs to be tested, sometimes cleaning can help them if they are loaded up with carbon.Comment
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having same problem with my 2004 225 4 stroke lost 500 rpms and burning a ton of fuel have been told its everything from fuel injectors to o2 sensors. I called yamaha and they said its the ethanol in the new gas and yamaha has not come up with a fix for this yet this problem is also happening with any other fuel injected motors.I have tried every fuel dry treatments out there and to no avail i recovered 200 rpms.Im ready to trade motor for an old 2 stroke with carbueratorsComment
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