2005 150 hp yamaha 4 stroke losing power

[225skeeter]

I recently bought a Hurricane deckboat with a 150 hp yamaha 4 stroke and it runs fine at idle speed but once on plane, it loses power. The boat had been in storage for about a year with a full tank of gas. I removed the clear cup/filter on the front side of the engine and the bottom of the cup was pretty dirty. Could old gas be causing this problem or possibly dirty filter or both? Any help would be much appreciated

 

[99yam40]

old gas goes bad
get rid of it and clean tank and lines.

If you would like to make sure run on a portable to see

But you need to clean out the system

 

[225skeeter]

i'll try a portable tank with fresh gas tomorrow & hopefully that'll be an easy quick fix to the problem.

 

[99yam40]

Injected motors have filters and screens that plug up

Monitoring rail pressure will show if there is a restriction somewhere