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BF9.9 making oil

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tugcapitan

New member
Hello Honda crew,
Have a 2002 BF9.9 making oil with fuel. Upon draining oil after winter, noticed red discoloration ( use red dyed marine fuel). Thought maybe it just leaked a bit while on it's (correct) side over the winter. But after oil, filter, fuel filter, water pump, thermostat, sparkplug change and carb rebuild, ran it for a week and noticed it made oil again (red like fuel). Ran great throughout.
Preliminary research on net indicates;
-damaged fuel pump diaphragm
-running too cool, fuel getting past rings.

Understand possible fuel pump diaphragm problem.
But, too cool problem usually associated with an engine that was not broken in correctly, and this one has run fine for years. However, symptoms supporting running cool include
-lots of salt deposit found when installing new thermostat, and when running, discovered threaded water flush port leaks water slowly. Imagine this means water flush valve bad. Corrosion on bolts under water flush port indicates it must have been leaking unnoticed last summer too.

Are these two problems related?
Anyone else experienced these engines "making oil" with fuel?
Recommended course of action?

Thanks in advance
 
What did the spark plugs look like when you changed them?

Was the old thermostat stuck open?

Did you remove the fuel pump and check it for leaks?

Yes, a poorly broken in engine will cause this problem, but since you said it has been running good for years, we will put that to the side.

If the thermostat is stuck open, it will run cold and will cause the motor to not run efficiently and not burn all the fuel. Also, since you cleaned the carburetor, there may have been something going on there also....like running rich.

You should check the thermostat one more time, to be sure that some of the salt deposits have not broken loose and lodged themselves in the thermostat....holding it open.

If you have fixed all those issues....thermostat, spark plugs, and carburetor, one of the things that could be left is that the rings may be carboned up.

Running a very slow speeds for a long time, also can contribute to carbon buildup.

If you can get your hands on some Yamaha Ring Free, and follow the directions, that will help decarbonize your rings...if that is the problem.

Hopefully, Jimmy D will jump in....he always has creative ideas when it comes to these motors.

Mike
 
OK...here I am...and....you two have pretty much covered it! Que the deflating Pac Man sound....wah wah wah.

This one is yelling leaky fuel pump to me though because it happens so fast. But, I've seen more "fuel production" on these with the stuck thermostats than anything else. Mike's suggestion about deposits breaking loose and sticking the new stat makes perfect sense.

It strikes me that tugcapitan's sentence "Ran great througout." might indicate we all should pour some treated gas in our crankcase!.....KIDDING! Just kidding Ya'll!

Good luck John and keep us informed about what you come up with
 
Thanks a lot guys, haven't been to the island to get at the engine yet, thinking early sept. Highly suspect leaky fuel pump so think I'll order one anyways to take with. Stuck open thermostat possible too, although it happened right after I put a new one in and flushed it out well, but... Old one was gross with salt. Gonna have to open up thermostat main housing too to replace flush valve, it was so salty in there it is now leaking too. Fired a bolt in it with Teflon tape to stop the salt water drips from causing more corrosion.
Will post again in sept.
 
To All:

Just a note, the Yama Lube Ring Free does not have directions for shock decarbing on the container. I just put a bottle in my tank yesterday and it says something to the effect "For shock treatment see your dealer for instructions". With Sea Foam, I have used 3:1 or 4:1 fuel to solvent. But the Ring Free seems far more concentrated, so does anyone have any idea of the proper ratio for the Yama Lube Ring Free shock treatment?
 
Installed a new fuel pump last sept before I put it too bed for the winter.
I'm back on holiday and am happy to report my 9.9 started first pull (I gave it so much love before hibernation!)

anywho, I've had the kids out ripping around enough to say that the new fuel pump seems to have solved the "making oil" with dyed marine gas problem. Yahoo!

Not sure if it's related, but I also bought a new fuel line and gas tank to replace sun baked stuff, and have noticed improved performance. With my wife and 3 small kids in the 12' tinny, we got up on plane this year where last year we didn't. Would a leaking fuel pump hurt performance? Or was it an old fuel line restriction do you think? So happy to be running so well.

Watch out fish, I'm coming!
 
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