250 4stroke losing power

[Snookered]

I have been around boats my whole life and have learned all too well the importence of taking care of your boat. But this has me stumped. Bought boat new in 2006 and it would periodically seem to surge and lose power after a long run at consistant rpm ranging from 4000 to 4500. (maybe once per trip at first) after bringing the motor into neutral no more problems the rest of the trip ( 8-10 hrs) Shop had no answer as it was not happening regularly enough for them to see. It has finally gotten to the point that it will do it every ten minutes and they changed the fuel pump at the advise of Yamaha to no avail. They do not have any ideas. I have read other threads similar today that seem to be concentrated on the clogged VST??? What is it and does this sound like my problem????

Fortunately the motor is under warranty but this has already cost me 3 tourneys and all of tarpon season which is my busy season.

Any advise would be greatly appreciated
(sorry for the spelling I was in a hurry)

 

[Snookered]

Re: 250 4stroke losing power

Well, it was not the VST or any of the fuel filters. Low and high pressure fuel pumps are also working properly.

Any advise?????

 

[JUSTINTIME]

Re: 250 4stroke losing power

check for fuel restrictions and have them plug it into YDS

 

[rodbolt]

Re: 250 4stroke losing power

the F250 is a single throttle body system. I would start by carefully monitoring fuel rail pressure, it uses six injectors with a single throttle plate. each injector has a screen as well as the high pressure pump. your describing a fuel pressure problem.
find a tech that has at least advanced 4 stroke and fuel systems certification on the wall or your sunk.