So , idling out of Stonington harbor , hear a "pop" . Raise hatch , do the once over , everything looks good. Get underway , port side won't pull rpm , like timing isn't advancing or starving for fuel. All gauges perfect , sounds strong at idle. Changed fuel and sep. filters , plugs , plugs not rusty . Ran out of light for test run so ?? Anyone suffered these symptoms? Bummin!!

Compression test and cylinder leak down results?

can you explain the pop, back fire, ?? something broke ?? sounds like it may of went into guardian mode

No test results , had comp tester but worked late and not enough time til dark . Planning on quickie run tomorrow afternoon to prob find out my issue is deeper than I hope . Possible electrical ? No warning beeps , sounds flat , can get 4k rpm max trimmed to the moon.

Sounded like a muffled backfire . New to EFI and computer control , baffled . Thought of having ocean perf do a code scan but have no warning beeps. To me it seems electrical but that could be me hoping for the bast!

Just caught your guardian mode comment , thought that initially , have the manual but couldn't seem to find anything in the manual about the guardian mode. Of course , I left the manual in the boat when I left the marina.

I would have it scanned it might point to something that's not setting off an alarm, what your feeling ( no power ) is symptom's of guardian mode the ECM is trying to keep it from damaging the engine, and you said it sounds fine at idle ??

Going to call in the morning . Should have called already , looks like a lost weekend. Thanks for the second opinion!

hopefully not all lost, good luck

If the engine still revs ok not under load (in neutral) good chance you have a vacuum leak from probably a hose that came off somewhere. Check for vacuum small hoses that
that would change the timing. Sounds like what happen to me once. Even had my mechanic in the boat and he could not figure it out. A friend found it. Small 1/8 vacuum line under the whipple charger in the manifold. It was effecting the timing through the ECU. It would rev up fine in neutral but once we tried to get on plane it would lay down. Not 525's but sounds the same