150 4 stroke help please

[bigfishbobby]

Hi guys, I am new here and was hoping for a little help. I have a Yamaha F150TLRC 4 stroke on my boat that I ran about once every month or so in the yard on a hose and never had any issues. I finally got to run it for the first time in about 3 months in the water and had issues at various RPM's with it bogging down. I would be running say at 4500 RPM's and all the sudden it would drop to 2500 then back up to 4500 etc like it was starving for gas. I could come down off plane and go again and it would happen again and again at just about any RPM although it was less frequent at lower RPM's.

I drained the gas tank way down a few months ago to limit potential ethanol problems, and put fresh gas back in before this trip. My gut tells me that I sucked up water off the bottom of the tank before refilling and that under power I am not getting enough fuel. Maybe a clogged fuel filter? The tank in the boat is stainless steel and only 2 years old. Any ideas? Thanks for your help!

[200090tlry]

Sounds like fuel

I just cut off my fuel bulb line and shorten it. You want the bulb to face up and down so it's working correctly. I also added oring around quick connection were it hooks up to motor.

[rodbolt17]

most likly the VST filters are clogging.
when was the last time the VST prefilter and the VST filter was cleaned/replaced?

[bigfishbobby]

good question

I don't know if or when it has ever been replaced because I never did my own maintenance. How involved is changing the VST filter? I am pretty mechanically inclined but don't want to get in over my head.

[rodbolt17]

its not hard, it does require the intake manifold assy to be removed.
takes about 1.5 to 2 hours.

[bigfishbobby]

thanks

Thanks rodbolt, the information here has educated me. I opted to take it to my mechanic this afternoon. After looking closer at the issue, it looked like the fuel filter in the front of the engine has broken down and the particles have passed through the system. I appreciate all of your help and hope someday I can repay the favor to someone else. Thanks, Bobby

[Sparkieboat]

it looks like a lack of filter maintenance can be a real issue with these four strokes..I have a 03 F115 that was not properly maintained either and i am having problems with it also. a good lesson here for others..clean and change your fuel filters every year including the VST filter..also add a good inline filter in between VST and low pressure fuel pump if you do not already have one.