oX66 compression #'s

[Triton420]

What are usual compression #'s on an Ox66? 2002 200 VMax. Engine warm, throttle wide open, fuel disconnected: 80-78-75-80-78-75psi. All within 10% but those seem low to me.

Boat suddenly started running rough and dead shutting off once on plane going about 40MPH. Half the time it would shut off trying to get on plane while running rough. 400lbs of coangler and gear, + full livewells so there was a LOAD
Fuel pressure 35psi at idle (verified VST running while on lake when this issue was happening)
Time to change O2, LP pumps plugs, VST anyways so fixing to do all that. Fuel filers less than a yr old.

Reason for checking compression was because lower left cylinder had some milky oil pooled in bottom cylinder I could see with borescope. Another had a puddle of either fuel or water in it. Was clear. Another cylinder has a penny sized piece of carbon buildup missing from the piston and looks like chunks of that in o2 bore.

[CJ1]

Check your gauge. The only way all the ring packs would be bad is dust and dirt or scuffed. Not likely in a boat. All within 5psi of each other. CJ

[yam911]

Double on check your gauge.

While on the somewhat low side, I don't see the compression numbers stated as being noticeable in operation.

A 10% difference would not bother me in the least. Mercury Marine uses 15%.

[javelin90]

Milky oil could be sympton of head gasket leaking. Sounds like a fuel issue or the fuel relay is intermittenlty failing.

[ssmithboats]

a ox 66 is a 2 stroke so there wont be any milky oil.