Rodbolt please help again.

[Fish-T-Cuffs]

I spoke to you a few weeks back about problems with twin 200 hpdi's with a cold starting issues.<br />I have set up a appointment for june 13 to get them hooked up to the computer. I went on my own and took apart the o2 sensors. I found LARGE carbon deposits on the outside of tube that slides into the block. Then large deposits inside the 02 sensors cage, and finally to find o2 sensors that are not heavily (lightly) covered by carbon. To my knowaledge this is the first time they have been touched after 650 hours. I cleaned them by spraying carb cleaner on everything and <br />scraping as much of the large deposits as I could. When I took the boat out for a ride immediately after starboard moter seemed to lag behind port. I lost some top end rpms, and gas consumption went up dramatically. 3800 I usaually burn 14 gallons /hr, and I am now burning 18/hr.<br />The boat was running great before I f****ed this <br />up, just hard to start. I am going down tonight to take out #1 plug to determine if I pushed **** into the cylinder which in return has fouled the plug, Top rpms where 5500, now 4900. Seems almost like running on 5 cyls instead of 6. Second motor really helps. Is it possible o2 sensors are shot, and not cleanable, or just worn out from lack of maintenance?? Is this drop in rpm possible associated with o2 and not spark or fuel?? Seems pretty coincidental that it was running great at high rpms The day before I messed with the sensors sensors. I also used the same gaskets and did not replace. They seemed to be in pretty good shape. Last question- I now start the motors up at the dock and quickly shift the boat into forward, This stops the motors from stalling and they turn 500 rpms while I am stilled tied up. So when they run on six they are fine ,but only 4 they fluctuate between 3-600 and stall every 10-20 seconds. Sorry about the long post, sometimes more info is better then less. Any input will be greatly appreciated . Please help the big bass are in! Thanks Mike

 

[rodbolt]

Re: Rodbolt please help again.

odds are the o2 sensors are done for, but wait for a qualified tech, they need to check/replace the low pressure pumps, test the spark plug caps, tune up the cooling system if its due, replace the plugs, clean the VST and replace the medium pressure inline fuel filters, if they put hose clamps and not the factory clips on the short line from the VST to the inline filter throw a fit until they do it with the correct tool and the correct clip. does not sound like these motors get much maint so catch up on all of it.<br /> but do tell them to start with a good decarb and then a compression test.<br /> the factory says the O2 sensors are out of the loop above 1800 but experience shows that if they dont work and it runs nasty at low speed its affected throughout the RPM range.<br /> when was the last time it had a set of spark plugs, 100 hours or so and they usually start failing, the Z300 we have problems above 75 hours.<br /> but new O2 sensor gaskets are a must, hopefully you have not contaminated the isulation with fuel/oil. if its contaminated you have to replace them.<br />the sensor element is not visible, the shield is what you scraped at.<br />odds are the computer wont say anything is wrong, I will bet you see a shift position code set and possibly a low fuel pressure code.<br />odds are they will have been set for many hours.<br />mostly what the laptop does is tell me whats not wrong.

 

[Fish-T-Cuffs]

Re: Rodbolt please help again.

changed the spark plugs and the thermos,waterpumps,batteries,lower oil,all three filters<br />(cannister,inline, and high speed) in april. I have the right clamps on the fuel lines. I havent cleaned vst in two seasons (since july 2004). I went to the boat tonight and as a suspected a large carbon deposit was directly wedged between the two prongs of the plug (large). Also additional residue on the threads inside the head of the #1 cylinder. I believe this may have been my problem. I do all the maintenance myself, I failed to realize the o2 sensors maintenance. my fault I have ordered a maintenance manual and hope this helps. I like to know how my motors work so i can fix them, this is why i know enough to get myself in trouble. Hopefully tommorrow I take her out and she runs strong ang the rough starting can be solved by diagnosis. Thanks again!

 

[Fish-T-Cuffs]

Re: Rodbolt please help again.

changed the spark plugs and the thermos,waterpumps,batteries,lower oil,all three filters<br />(cannister,inline, and high speed) in april. I have the right clamps on the fuel lines. I havent cleaned vst in two seasons (since july 2004). I went to the boat tonight and as a suspected a large carbon deposit was directly wedged between the two prongs of the plug (large). Also additional residue on the threads inside the head of the #1 cylinder. I believe this may have been my problem. I do all the maintenance myself, I failed to realize the o2 sensors maintenance. my fault I have ordered a maintenance manual and hope this helps. I like to know how my motors work so i can fix them, this is why i know enough to get myself in trouble. Hopefully tommorrow I take her out and she runs strong ang the rough starting can be solved by diagnosis. Thanks again!

 

[rodbolt]

Re: Rodbolt please help again.

if your going to do your own maint you MUST purchase some basic test equipment. the diagnostic lamp,O2 sensor test harness TPS test harness and a decent DVM along with a service manual and a medium pressure fuel guage.<br /> its no shame to get in trouble,once.<br />that is a complex machine ya got there and if you dont understand how and why the stuff is on the motor it can bite you.<br /> but it all goes back to the basics. suck,squeeze,bang and blow,everything else on the motor just helps it go.<br />when looking at the fuel subsystem break it down to its 3 basic subsystems,low pressure,medium pressure and high pressure, all gotta work. the ign is the same way, look at the ign producing components then the ign controling components.<br />other than the plug caps electrical failures are rather rare on a yamaha, usually its a sensor or fuel.