2021 250 Pro Xs start up and Possible lower unit Issue

[Dav0957]

2021 Mercury 250 Pro Xs 102Hrs
2B786374

Ive noticed lately on first start up of the day I no longer get that strong crisp start up but more of a slight stumble for a split second. After that runs fine all day and starts crisp the rest of the day. Engine has just over 100hrs could it be time for spark plugs already? Possible fuel pump not getting up to pressure? Weak injector?

Also while coming off pad I've been noticing a vibration but only when letting completely out of the throttle if I feather the throttle coming to slow stop I dont notice it at all. Normal or possibly the lower starting to give up?

Boat was serviced at 20Hrs and again at 100Hrs. Oil change Lower unit fluid Fuel filters.

[EuropeanAM]

David:

I would recommend getting this checked- especially since it's been only 2 hours since you indicate you had it serviced.

Loose propeller or prop hub problem are the first things that come to mind on the gearcase side.

As for the starting situation- that's something that would need to checked in-person, hands-on. While it's unlikely that an injector or fuel pump is the cause (you would likely have other complaints), there are a few items that can contribute to this that may need attention (even including items as simple as the AGM Cranking Battery with at least 975 CCA Capacity... or it's connections).

[Dav0957]

Thank you for the response. I do my own service. I will recheck prop nut torque and hub seating although it is a brand new hub and a fresh Croxton worked Fury. Im gonna start with plugs as Ive seen them do funky stuff in other applications. I will check battery connections tonight and yes the battery is an AGM Cranking battery with 1000 CCA. Its had the stumble cold start issue for about 20hrs now. It runs great and that being the only symptom i tend to forget its even there but it seems to be getting slightly worse. I hate being boatless as I fish 3-4 times a week but ill take it in if the new plugs do not alter the condition.