[George Sansone]

I was heading offshore at 3700 rpms and the engine started making odd noises,shut down,took off engine cover and saw nothing leaking or abnormal .Fuel water filter was ok , checked the plugs and all were normal except the #2 cylinder ,it was dry and burned. I was able to limp back 13 miles to my slip at 1000 rpms,it would make alot of noise when rpms were increased above 1100 . When I checked the compression 1 and 3-6 were 120 lbs #2 was 0 psi. I have really have babied the motor:always flushed for 15-20 minutes, always used 100% synthetic Penn 2 cycle oil, cleaned all oil tanks ,fuel and oil filters,added new oil injection pump and lines ,rebuilt all three carbs,new fuel pumps, new water pump,pop-it valve etc. What would cause the dry black plug ,the carbs and oil injection system are like new? The Yamaha dealers in my area of Southern Calif. will only replace powerheads and not just one cylinder. $5700-$6500.00 for a new powerhead on a 12 year old motor?? Thank you

[Ray Neudecker]

The obvious answer would be a carb problem. Only reason I ever find a burned plug on these motors. No reason why a shop couldn't rebuild for less than the cost of replacement power head. Don't know the thinking of shops that won't rebuild motors. A very common practice is to rebuid in our area.

[andy6374]

Find a new shop for starters.Pull the head and take a look at the cylinder wall and piston. It wasn't the oil injection as it oils all equally. I could have been caused by many things, like a gummed jet in one of the carbs resulting in a lean condition. Wait for the rebuilders on this site to give you the next step.

[rodbolt]

its possible you plugged an oil line check valve and lost oil to a cyl. happens on rare occasions, my bet would be more on a partialy clogged main. check the shift shaft for corrosin as well. most 93 model motors in my area are to corroded to take apart. nothing like doing a rebuild to have it come back in 6 months with a hole corroded into the crancase from the fwd edge of the V. or for the water passage feding the left and right banks to blow a hole in it.as far as cost estimates i would not even give an estimate on how long it would take to tear a 93 model down. but to estimate the cost and feasibility of a rebuild you will have to tear it down. if it as an oil failure odds are it took the crank with it. any6374 on the carburated precision blend yamahas the cylinders all oil independant of each other or fuel. its injected behind the carbs into the reed box area. is this a 93 model or a 99. trxx indicates a 99 a 93 would be trxr. in fact the x as the third alpha charater does not show up . recheck your model number and repost. a 93 25" motor will be txrr and the 99 wil be txrx. the 4th alpha charater tells the story of year model for the US market.

[andy6374]

My bad fishndoc.rodbolt-Thanks for the info on the oil injection. I only assumed it was like a VRO . Good thing this foul up didn't cost anyone $$$.

[rodbolt]

andy the EFI,not HPDI, motors place the oil in the VST and the fuel/oil mix is then delivuered Via the fuel system, part of the confusion araises from the statement of being a 93 model with an X(99) model designation that could be EFI. thats why sometimes its critical to ID the model. there are actually two years that use the D as a designator,90 and 05 both use the suffix D as a model year code. if I just typed a 150txrd you would have no way of telling if it was a 90 model or an 05 model 150. no worries, if something is technically incorrect and I catch it ill try to correct it, I hope others will do the same for my technical incorrect stuff shows we are all human.