'06 F115 runs rough; rpm's drop; warning buzzer

[hawilson2]

From a standstill, if I give it a lot of throttle the rpm's start climbimg but eventually the engine runs rough, drops rpm's, and the warning buzzer sounds. The buzzer shuts off at 1500 rpm. Plenty of water pressure and engine temp is fine around 123F so it should not be the temp sensor.The engine remains running. If I start slowly and slowly give it gas it seems to run fine.The engine starts and idles great. I have 200 hours on the engine and around 100 hours I changed the internal fuel filter and an external racor 10 micron fuel filter/water separator. I am about to install racor's new 2 micron filter and a new internal fuel filter. I do believe it is a gas issue. I have recently started testing my gas for ethanol and so far have put in 20 gal (of a 30 gal tank) of non-ethanol regular fuel. It did not appear to have any water in it on inspection. Any other suggestions besides changing the filters I mentioned? This just happened today fishing on the way back in. From 4 stand still starts I had the problem 3 times. From 2 slow starts it ran fine both times. Before that it ran great.

 

[hawilson2]

Re: '06 F115 runs rough; rpm's drop; warning buzzer

Update on what I found so far. i changed the oil 100 hours ago and have been lax on checking it. I just checked the oil and it barely registers on the dip stick. Low oil will set off the alarm and reduce the rpm. It only happened when getting going quickly which severly raised the bow and dipped the stern. I have followed all prescribed schedules and it appears to be burning a lot of oil. Would a leak down test be in order? I do not feel comfortable with that much oil being burned. It is under warranty. Any ideas or thoughts? I do not believe I hurt the engine. It reacted as expected.

 

[BaileysBoat]

Re: '06 F115 runs rough; rpm's drop; warning buzzer

The big problem with these engines seems to be with "making oil", not using oil.

How often do you check the oil? Did you put in the required amount 100 hours ago, and have you looked for a leak? The oil filter gasket would be the first to check.

At 100 hours you are due for an oil and filter change anyway. I suggest you use the Yamaha oil and filter, and check the oil every 20 hours to track consumption.

 

[hawilson2]

Re: '06 F115 runs rough; rpm's drop; warning buzzer

Used the recommended amount (FC-W oil) 100 hours ago with a yamaha filter. No visible leaks anywhere. You know I examine the engine quite frequently to see if anything like oil leaks or corrosion are occurring. Not sure why I don't check the oil more often. I will now. I just bought a bunch of parts for what I call my 100 hour tuneup. Oil and filter were 1st on the list. Originally read about the making oil issue and repropped after that. Now I reach max rpm (6000) at WOT with a normal load. Had to go to a 20 pitch prop to get there from higher RPM's, I believe. I believe I am propped right now. Still do not know if I feel comfortable burning that much oil. Seems like there may be a problem.