Engine Losing RPM and Stalling

Engine is a 2019 Mercury 60hp Command Thrust on a Crest pontoon.
Model: 1F60453LZ

Last fall it started losing power at high rpm and would stall. Sometimes it would start immediately. Other times not.

I replaced all the fuel filters, spark plugs last fall and winterized it.

This spring, the same problem appeared when I launched it, at lower rpm (1500).

I did some research and concluded that the fuel pump was the issue so installed one in April. Through last week, that solved the problem.

But this week, while out on a sunset cruise, at 1500 rpm, the engine started shuddering. I quickly pulled the throttle back to idle and it continued to run and idle perfectly.

I put it in gear again, throttled up to 1500 and after 10 seconds or so, it stalled.

I squeezed the fuel bulb on the tank but it was already pretty firm. However, the engine started and ran perfectly as we returned back to the dock.

New fuel was added about 10 days ago and the boat has about 1/2 tank of fuel.

Any insight would be appreciated.

Sounds like it is fuel related (which means it's probably electronic). I'd start by rigging up a fuel pressure gage and seeing if the pressure stays up when this problem occurs. If so, start looking at the switch box (CDMs if that's what she has), stator and trigger coils. A DVA meter is a great help for doing this.

Jef

Update: I did a fuel pressure test and found the issue. At idle up to about 4000 rpm, fuel pressure was a consistent 42psi. Above 4000 rpm, it would drop and fluctuate around 15-20psi. The boat was under warranty so the local dealer came and got it. The high pressure and low pressure fuel pumps were replaced with a thorough cleaning of the VST (Vapor Separator Tank). The Service Mgr. said it's a known issue with this engine so it's something I just have to be aware of in the future.