BF 150 slight loss of power

After fishing and running about 50 miles within 4 miles of home my starboard engine changed pitch slightly followed by a decrease in RPM from 5000 to 4300 and fuel mileage went from 2.2 mpg to 1.2... Worked throttle up and down no change then seemed to get a little better. Port engine would turn 5400 normally 5600 WOT starboard only 4900 rpm WOT. Pulled both engines down to same rpm and economy came back to almost normal. Figure the port was a little low due to starboard not putting out its share. Came off plane boat is heavy (Everglades 240cc) so was thinking it wouldn't want to come back up on plane but did fairly normal but was very obvious lower power on the starboard engine. Engine is a 2006 with 260 hours no alarms ever.. Looking for ideas where to start. Will pull plugs, as well as gear case oil (just changed to make sure no leaks and undue friction) and go from there (the normal fuel filters will be checked as well) any other ideas? Engine had a definite change in pitch but maybe just from the change in RPM felt like we had snagged something that was putting drag on the bottom of the boat but checked just to be sure and it was only one engine so knew that wasn't it. Any help where to start would be appreciated!

I'm not expert on the 150's but a couple of quick general things to check come to mind...
1. Pull the prop and make sure nothing is wrapped around the prop shaft.
2. Make sure your water intake vents are clear.
3. Check to make sure the throttle cable has not slipped. There should be instructions for adjusting the throttle cable in you owners manual.
4. Test to make sure each plug is firing normally with a timing light or by pulling each plug one at a time to see if it has a major effect. Note that often times a plug will act normal at low speeds but will start to fail at higher speeds and pressure. So pulling the plugs and comparing them to each other may give you a better indication if one is failing a higher speeds.
5. Drain the VST.
6. Drain the external fuel/water separator, and check the onboard fuel/water separator and drain if necessary.

do you have 2 fuel tanks ? or one tank ?

One tank did a little snooping today checked in line Racors dual one for each engine clear as a bell... Never been any ethanol in these engines. Took the boat out today with a friend to check things while running and ran perfect... So odds are nothing major just potentially intermittent. Maybe something floating around in fuel pump / bowl or??? Right now don't know. Never seen them go away for long so sure it will come back. Of course engine wasn't hot so maybe related??? Ran 10 mikes and no issues.

Ye. It will happen again.. I would check the fuel filter in vst tank. Make sure there is no dirt or water
it is white mesh screen filter.

10 miles is pretty good test drive. On your 50 mile run home when the problem presented, was your stbd engine getting more bow spray than the port maybe? Just a thought as I ponder the problem.

Talklessridemore said:

Ye. It will happen again.. I would check the fuel filter in vst tank. Make sure there is no dirt or water
it is white mesh screen filter.

Click to expand...

This is where my money is.

JGMO no was in calm water at around 4700 rpm 31 mph at the time... Did nothing to it in the time between it acting up and running again... Just time in between. I will shoot for pulling and cleaning / replacing the fuel filter... Looks like a good place to start although am careful what fuel I put in it. The more I think about it I seem to remember a slight loss before that corrected itself very quickly... Thanks for the input everyone!

Yep, in that case I would agree the filter(s) would be a logical place to investigate.
Good luck and I hope you find something definitive to get some peace of mind.