Im looking at a 2000 454 mag mpi. Engine has 285 hrs. Any suggestions, likes or dislikes about this engine. Any advice on service to keep it reliable is greatly appreciated. All of the hoses have been replaced and its been routinely serviced. Any issues with the fuel system or upgrades? Any vapor lock issues. The engine is in a Baja H2X if that helps...

They like to vapor lock when its hot and humid, especially if you use ethanol fuel. To lessen this, crack your engine hatch and run your blower when you dock or anchor.
Other than that just change oil and normal maintenance.

Thank you for the info. I’m in Louisiana so hot and humid is what we got. Is there anything I can do or add to lesson the vapor lock? Duel fuel pumps or an extra cooler?

Run a return line, lots of threads about it.

Ill check into it...

Great motor but just to be on safe side I would check exhaust manifolds and risers for corrosion. Flush or replace based on what you see. Other than that normal maintenance and enjoy.

Is vapor lock a problem with cool fuel AND vst equipped boats?

My 1996 454 LX MPI's with VST's haven't vapor locked once in S. Fla. over my 5 yrs of ownership.

I’m seeing quite a few boats with built engines with carbs. I’m wondering if I should go that route. I’m wanting reliability. The wife isn’t really liking the H2x with the bow conversion that I found. She wants a bow rider. I want speed.

he should not have a VST as that quit in 1996 model year.

Gen 2 cool fuel should be installed if the engine is OEM stock and if not molested

when the engine was new - it did not vaper lock - so what has changed - many things - old fuel pumps - old fuel lines - cooling system is lacking in that area and so on - and the one that everyone misses is the thermal heat transfer grease that is needed for the gen 2 cool fuel PUMP. No one brings this up. That needs to be done every five years and new fuel pumps need to be change before they totally give up. Old fuel pumps draw more amps that inreturn creates HEAT - high heat boils the fuel away and or causes cavitation.

Im in Texas and 110 during the summer with higher than bath water temps as well. I have many boat owners with 502 s and 454 s that do not Vapor Lock ever, including my own 454 ho mag. 2000 year model and has not ever came close to vapor locking. Its all about maintaining and how old and the shape the engine fuel and cooling systems are. You can also install the OEM Merc vapor lock kit as well.

Heck the old carb V 6 mercruiser would vapor lock more than these efi engines

Great info. Im really liking this boat. Its a H2x with a bow rider conversion but the wife doesn't like it. The boat is also 1100 miles away.