2004 Yamaha HPDI Excessive Smoke

[pecky]

First time post for me as I just discovered the site. I have 135 hours on my 150 HPDI (2004 model). Ran it for one season in fresh water. Most hours from *****ing. Motor ran great all last season. First time out this season I noticed smoke coming from the exhaust (not a lot but more than you'd expect from an HPDI). I assumed it was because of the 40 degrees water/air temp and fogging oil from winter storage (I had it winterized in the fall by a Yamaha dealer). Other than the smoke, the motor ran great during 6 hours of *****ing. When I picked up to head to port I noticed the boat topped out at only 35MPH and only 4500 RPMs. Last season I would get 45MPH and 5500 RPMs. I've had it out twice more with same results. Checked the prop which is fine. Pulled the plugs today and a couple were pretty 'grimey'. I plan on replacing them tommorrow in hopes that might solve the lower RPM issue. The smoke has me concerned and today I noticed the overheat guage flashing although the cooling stream was running strong and the alarm never sounded. Any thoughts?

[boats.net]

Probably need to do a compression test, replace plugs and run a shock treatment of Ring Free through it. You might test the alarm buzzer by unplugging pink wire on temp sensor thats located on top of cylinder head's and touch pink wire to engine block(ground) with ignition key on and the alarm should sound.

[pecky]

Thanks for the feedback... the motor is still under warranty so reluctantly I'll probably just have to pull it and bring to the dealer. Through the process of elimination, I figured out the motor is running rich which fouled the plugs. Put new plugs in and it ran like a charm: no smoke and got my 5500 RPMs back. However, after running for a few minutes, the smoke started coming back. In the process of changing the plugs, I noticed some oil on the floor of the engine compartment. Appears that oil is leaking from the manifold behind/below the gas fuel filter. I'm not a mechanic so I'm not sure what that part is. There are several hoses (that appear to be oil lines) running in and out of it. I assume it's the oil injection pump. Any possible easy solution (like tightening some screws) for a layman before I take it to the Yamaha rep? Unfortunately, those guys are backed up like crazy this time of the year and I hate to find out how long I will have to wait before I get the boat back in the water.