Gasoline is entering the crank case and causing the oil level to rise which seems to be known as "making oil". I started with a fresh oil change and ran the boat WOT for about 2 hours. After the run the oil level was substantially higher and I drained about a quart to get to just above the hash marks on the dipstick. Common causes: 1.) open thermostat - causes a rich mixture that gets flushed by the rings. I checked the thermostat and it was closed until 130-140 degrees so I think it is okay. 2.) Fuel pump diaphragm may be leaking and injecting gas directly into the crankcase. This is the most likely culprit but no gas leaks out when squeezing the bulb with the pump out of the engine block. Maybe this isn't sufficient pressure to cause the issue but it is the only test I know of that I can perform on my own. Anyone have any other ideas?
I will likely replace the fuel pump since there is no repair kit available. The Merc site lists the part number as: 880890T1 but the part is no longer available. Amazon has multiple listings for that part number which is supposedly the same part as Yamaha 68V-24410-00-00. I can buy one from Amazon for $40 but the reviews are not great. I am leaning toward buying the official Yamaha part for $220 but can't find a better validation on fitment other than offerings on 3rd party sites.
Any suggestions on other possible causes and tests are welcome.
Thank you
I will likely replace the fuel pump since there is no repair kit available. The Merc site lists the part number as: 880890T1 but the part is no longer available. Amazon has multiple listings for that part number which is supposedly the same part as Yamaha 68V-24410-00-00. I can buy one from Amazon for $40 but the reviews are not great. I am leaning toward buying the official Yamaha part for $220 but can't find a better validation on fitment other than offerings on 3rd party sites.
Any suggestions on other possible causes and tests are welcome.
Thank you