I know somebody on here has experienced this with your Mercury outboard as I've heard this is somewhat a common issue but have yet to hear a clear solution.

Equipment: 2012 Mercury Outboard 115 EFI 4 Stroke
Problem: Engine starts fine and runs strong for about 10 seconds then really starts to stumble. Pull off the throttle and wait about 5 seconds then she builds back up and ready to go. Fills like it gets gas then runs out and has to be filled again then runs out, etc. The motor really chugs and struggles when it does stumble. It could possibly be doing just the opposite and flooding its self out but smell that way.

I changed the plugs and fuel filters. Talked to a guy at the ramp and he had something similar and ended up changing a sensor and it worked. He didn't know which sensor but said it was in the fuel separator tank. I think he might've changed the fuel float since I spoke with Chatlee and they said that might be the issue. Before I go throwing new parts on I wanted to see if any of you encountered this issue and what you did to fix it.

Last night once I was trying to return to the ramp it wouldn't start. I pulled the fuel line apart at the filter and gas spewed out like normal. Put it back together and she started and would run at 3200 RPMs.

I typically run normal gas (with Ethanol) since I use my boat a lot. I get out at least once a week or more. Boat won't sit more than 2 weeks max. I did fill it with Ethanol free gas after this issue started and it made no difference. I have no plans of ever putting Ethanol gas back in even if it has no correlation to this issue. They started selling Ethanol gas at the Sheetz near the Walmart (near Ihop) in Holly Springs before you get to Avent Ferry Road by the way.