Yes. A 4.3L would be very possible. There would be bugs and hurdles until it was ironed out though. Especially with an OMC shift interrupt system, since EFi is very good at holding specific idle rpms. It would have to be triggered with the ECU.
I’ve been looking into EFI for my 3.0l as my wife actually wants it for my big ( er ) boat as my little 14’ with DF25A is literally turn key and go.
You have 2 options. Affordable Fuel Injection which is plug and play but your OMC shift interrupter drops rpm rather than just interrupts spark. They may not have a solution. And their kits are not fully USCGI compliant ( they can pass a visual ).
Holley Sniper is self learning. You can make it work fuel only but it will freak out when the rpm drops for sure so ymmv on that.
Neither will be as easy as a carb to get going but should be good and reliable when done. You’re not getting it for less than $2k. It’s worth is if your willing to pay and put up the time
I have the Mercruiser shift interrupter installed, so that should not be problem. The $2000+ ticket is a very convincing reason as to why not, specially since my current setup is fine and $2000 is enough to go to Costa Rica and fish offshore for 2 days.
As far as the reason not to the cost is pretty high vs the benefit which is really only better cold starting running smoother cold idle. I don’t think it’s giving you noticeably more power or economy. And here in salt water land EFI has a lot more wiring and possible points of failure if the wiring harness isn’t up to use in damp climates. When I do a carb rebuild it’s about $50 parts for the best Quadrajet rebuild kit. The last mechanical fuel pump I replaced was $80 from Summit Racing and the one I replaced was 30 years old! I think carbs make more sense for old boats. But hey EFI is nice, esp for younger folks not used to carbs….
I'd keep the carb, if it's setup properly. On an auto that is constantly changing rpms the efi is beneficial, on a boat that is at a constant rpm, load, the carb is better. Your boat doesn't coast, go up hills etc.
