Fuel in oil

[sstiefvater]

I have a 2000 Yamaha 115 4 stroke model # F115TLRY.<br /> <br />I have a lot of fuel leaking into the oil. I can change the oil the run the motor for an hour and then pull the dipstick and a oil gas mixture will be over flowing. I have had this problem a few years ago when the motor was still under warrenty and had it repaired, but I cant remember what was replaced.

 

[JB]

Re: Fuel in oil

Howdy Bikertramp.<br /><br />Welcome to iboats. <br /><br />See the article in the Engine FAQs about 4 strokes "making oil". It covers a few causes.<br /><br />Good luck. <br /><br />(247)

 

[sstiefvater]

Re: Fuel in oil

Yes I read the article, but it is talking about small amounts oil. And it also mentions problems with the fuel system. I would like to know what in the fuel system mat cause this problem. I have a lot of fuel in the oil at the piont that when you pull the dip stick the oil/fuel miture will shot out at you. I dont want to start changing part without a educated quess of what the problem is.

 

[rodbolt]

Re: Fuel in oil

do you have a service manual? the four stroke 115 mercury manual is more informative than the yamaha manual. that would be a good place to start. I have the merc manual at the house if you have any questions.<br /> the EFI system that motor uses is quite simple but you have to understand what it does and why before attacking it.

 

[sstiefvater]

Re: Fuel in oil

Yes I have a Yamaha manual, but is not much help. It the Murcury manuel usefull for a Yamaha?<br /><br />Thanks for everyones help.

 

[rodbolt]

Re: Fuel in oil

yes it is, but posible causes for that much fuel in the oil are defective t-stat causing overcooling, bad VST neddle or a stuck ingector. you will need a fuel presure guage to test fuel rail pressure and a temp stick or gun to asses block/head temps.<br />the mercury manual goes into more detail on how the systems work than the yamaha manual.<br /> the merc EFI four stroke 115 of that vintage was basically yamaha with black paint.