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  • Unburned Oil in Exhaust

    I've having some oil related problems with a 1992 200 hp Yamaha. First, the oil resevoir under the cowling does not seem to fill up. Second, I've noticed that I've got some sort of unburned oil coming out of the thru-prop exhaust when the motor is running. I also noticed that my idle has dropped about 300 rpm. Any ideas what I could be dealing with?

  • #2
    The upper line on the engine oil tank is the full level. If you have unburned oil and drop in rpm's it's probably not running on all 6 cylinders which could be a compression, ignition or fuel problem.
    Regards
    Boats.net
    Yamaha Outboard Parts

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    • #3
      I think I've figured out that the transfer pump on the remote oil tank is out, which is why the resevoir under the cowling is not filling up. Seems pretty simple to replace.

      As for the unburned oil in exhaust, you said it's either compression, ignition, or fuel. I recently had the compression checked and it came back fine. So, I'm hoping I can eliminate compression.

      It's a twin engine setup and both engines draw from the same tank. The other engine is running fine. I'm thinking that that eliminates fuel. What would you look at next?

      Thanks for the help.

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      • #4
        Vitz, since its a twin setup you can do a little more troubleshooting. Does the problem remote oil tank pump run if you toggle the emergency switch? If NO, then take the remote oil pump harness from the other engine's remote oil tank and plug it into the problem remote oil tank pump. Try the emergency switch on the good engine and see if it will run the problem remote oil tank pump. If it does, then the problem is in the harness on the bad engine. If it does not, then yes there is a problem with that pump and it needs to be replaced. Post back with the results you find from this test.


        Mike

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        • #5
          It could be unburned fuel and not oil, does it evaporate off water after a minute or so? Try pumping fuel primer bulb when engine is running, if makes it run worse then may have ruptured diaphragms in fuel pumps. Try new spark plugs, may have fouled plugs.
          Regards
          Boats.net
          Yamaha Outboard Parts

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