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My 2004 Yamaha 225 HPDI has low water pressure problems. It looks like there are lots of us with the same symptoms but the common path suggested by dealers, Yamaha and folks on the net is what I have already done; and it does not correct the problem. Does anyone have a real solution to the following problem? 2004, 225 HPDI, Less than fifty hours run time, No hot horn alarms yet, Use to have 2-3 psi at idle and 17 psi at 5600 rpm’s. Pressure dropped to 8-10 psi at 5600 rpm’s and no readable pressure at idle. Tattle-tale on side of motor always has a stream although weaker than it use to be at idle. Good flow out of exhaust in rear of engine. Changed water pump, changed pressure gauge and calibrated it, flushed system several times, changed intake screens, changed engine height, inspected pop-it valve, stretched pop-it spring, checked hot horn function. After all of this, I have virtually no readable pressure at idle and 10-12 psi at 5600 rpm’s. This apparently meets Yamaha’s criteria of 11psi but I don’t care to have marginal water pressure on a “new” motor.
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How's it do when you take the screens off? I heard someone else tried that and it improved the flow. My '01 VMax has the old side inlets so I can't try it. I was just curious if it really does help or not. Seems Yamaha has a problem they won't fix.
Mike -
tph,
I noticed that you said in your post that there was good flow out of the exhaust in rear of engine. If you mean the two relief holes towards the top of the upper casing, then that might be your problem.
It is my understanding that there should not be much cooling water coming out of these holes unless the pressure relief valve is opening. The PRV is designed to open, I believe, when the water pressure in the water jacket exceeds 20 psi.
Even though you have checked the PRV, it still may be opening up too soon, or the PRV seat is cracked, or otherwise not smooth and allowing water to bypass the water jacket.
I would replace the PRV and seat and spring - don't think they are very expensive.
Good luck, and let us know what you find out.
Ken KComment
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