Optimax issue

[Daquanevans]

I have 2007 mercury optimax 175 on an 2008 211 Mako, recently purchased used from dealer no warranties or anything strictly as is. Not sure of the boats history, it’s in great physical shape. Compression was even and solid on all cylinders had the dealer check and show me before purchasing. The motor runs perfectly out of the water, idles great no issues it when it’s under a load it has an issue when at full throttle attempting to plain out, any where in between idle and full throttle there’s no issues only when the throttle is down. It builds rpms as it’s supposed to stays around 6k but it’s struggling to plain out there’s about 8-10 seconds of struggle then it jumps open to full throttle and stays there relatively well. I thought maybe it was an prop issue or fuel issue changed the prop went from 19 pitch to 17 not much change in how it ran. When I got the boat it was low on fuel took it and filled it with non ethanol ran it once saw how it was doing thought fuel issue so I bought quicksilver fuel treatment ran it for about 2-3 hours last weekend still not much change. Pulled the plug out of the VST hoping some trash would drain nothing really came out changed the fuel filter twice no change. Any ideas or suggestions? I have video of what it was running like in the water

 

[jcole108]

Check your fuel lines, I think it is the gray ones that have the ethanol lining in them. The lining comes loose and rolls on the inside. Replace them with the new fuel lines, I believe they are blue.