Shipyard Isl. Marine Engine Parts - help on 2003 200 HP OX 66 SWS II

Andy,

After reading many posts on this forum re: same subjecy I recently purchased and installed from your parts website 2 low pressure fuel pumps, power head fuel filter with new o ring. Fuel water Seperator, 6 new spark plugs, new high pressure fuel filter and new gasket for VST after cleaning VST, new primer bulb.

My original problem was bogging down from 4300 to 2000 rpm and surging back again especially in a heavy sea. After installing the replacements I did notice significant improvement however still have some hesitation and drop of aortic. 200-300 rpm around 4200 rpm and a seemingly loss of power, especially after a long period of trolling at low speeds 2-3 knots. I am not very mechanically inclined and feel I am about at the end of my ability to fix. The only thing I haven't done yet is clean or replace the O2 sensor. While I have significant improvement I still do not feel confident with the motor especially when entering some of the treacherous inlets we have up here in NJ. Want to have full confidence. Could the O2 be the culprit for this small drop in rpm, hesitation, loss of power or do I need to break down and give the boat to my mechanic. Is their a specific procedure for cleaning the O2 sensor, I have been reluctant to take it out as I understand it is sensitive and I don't want to do more harm then good. Am now running ring free and shocked the fuel with 2x per my Yamaha mechanic to try and clean O2 sensor without taking out but have not noticed any improvement to date after about 60 gallons of gass and 16 ozs of Ringfree have burned thru the engine. Any help would be appreciated and BTW I am sold on your parts service, excellent service and help on the phone when I ordered the parts.

Thanks for your help.

I would clean the O2 sensor and draw tube. If its not working correctly, there can be some funny running issues. http://www.simyamaha.com/category_s/1841.htm

Was there any crud in the VST? Reason I ask if it was bad, you might want to consider having the injectors cleaned too.

Andy

I would clean the O2 sensor and draw tube. If its not working correctly, there can be some funny running issues. http://www.simyamaha.com/category_s/1841.htm

Was there any crud in the VST? Reason I ask if it was bad, you might want to consider having the injectors cleaned too.

Andy

Andy,

Thanks so much for your quick response. When I cleaned the VST their was very little contamination. The old filter was clogged with some fine particulate but no crud and just a very, very small amount of fine particulate in the champer itself. otherwise it was clean. I cleaned this small amount out when I replaced the high pressure filter. Thanks for the link on the service bulletin. However it only contained page 1 of 6 on the u2 sensor and was missing the pages regarding the actual servicing/cleaning. Could you please resend, I am going to attempt to clean it myself today and see if that makes a difference. Thanks again for all your help. You've got a customer for life!:thumbsup:

Andy,

Thanks so much for your quick response. When I cleaned the VST their was very little contamination. The old filter was clogged with some fine particulate but no crud and just a very, very small amount of fine particulate in the champer itself. otherwise it was clean. I cleaned this small amount out when I replaced the high pressure filter. Thanks for the link on the service bulletin. However it only contained page 1 of 6 on the u2 sensor and was missing the pages regarding the actual servicing/cleaning. Could you please resend, I am going to attempt to clean it myself today and see if that makes a difference. Thanks again for all your help. You've got a customer for life!:thumbsup:

Please ignore above request to resend, my IPad would not show anything but page 1 but thlaptop does show. thanks again for the info!