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MPI vs carb

Posted: March 10th, 2021, 9:57 pm
by turin0905
I bought a Carver Mariner 350 1999 with two 454 XLI engines. I have no idea the conditions of the fuel injection system as they have not been used for 2 years. I want to repair the engines. Would it be a good idea to switch to carburetor system?

Re: MPI vs carb

Posted: March 10th, 2021, 10:16 pm
by tomschauer
I cant think of any reason you would want to go from near current technology back to the 70's?
I wouldn't buy a boat that didn't have fuel injection. I've rebuild to many carbs over the last 40 years or so.
FI, gives you clean quick starts, better fuel economy any better performance.

Re: MPI vs carb

Posted: March 10th, 2021, 10:53 pm
by buster53
tomschauer wrote:Source of the post I cant think of any reason you would want to go from near current technology back to the 70's?
I wouldn't buy a boat that didn't have fuel injection. I've rebuild to many carbs over the last 40 years or so.
FI, gives you clean quick starts, better fuel economy any better performance.


This.
Also, why not see how the engines run before you do anything?

Re: MPI vs carb

Posted: March 11th, 2021, 3:22 am
by Midnightsun
Not too many places know what a carb is today. I can go back 15+ years and had difficulty having my carbs serviced. In fact I had to send them to Florida where there is a profusion of boats to get it done as it seems this is the only place a carb can still be found today which is on older boats. I would definitely not go back to carbs from an existing FI system. Almost equivalent to going back to radio and getting rid of the TV.

Re: MPI vs carb

Posted: March 11th, 2021, 7:23 am
by Viper
Congrats and welcome aboard.

If you haven't had the engines running yet, I wouldn't jump to any conclusions about how they'll run after two years of non use. The typical issues that show up as a result of long term storage can be dealt with.

Not only is it counter productive to switch back to a carbed fuel system, it'll be more costly and time consuming than you think. It would wouldn't be as simple as removing injectors and a few EFI components. That model would require a new intake manifold, a redo of other fuel delivery hardware, wiring, ignition system mods, cooling mods, the list goes on. Carbs have their place but in this application, retrofitting is not practical or desirable.

Let us know how she runs and any issues you come across, we may be able to offer up some recommendations.

Re: MPI vs carb

Posted: March 11th, 2021, 8:09 am
by RGrew176
Like others have said I don't know of any reason to go back in time to older tech. Good luck with your Carver I hope your issues are few and far between.

Re: MPI vs carb

Posted: March 11th, 2021, 8:33 am
by g36
im probably wrong but i believe like me with crusader 454xli engines you have throttle body injection (tbi) not mpi. this is bascically a carbueratlor with 2 fuel injectors in it. there are rebuild kits for them and theres 3 fuel filters inline from the fuel tank to the tbi. if your having issues i would change these filters first before doing anything with the fuel injectors

Re: MPI vs carb

Posted: March 11th, 2021, 11:15 am
by km1125
I'm with the others.... ditch that idea of going back to carbs.

Fuel injectors are pretty reliable and unless someone screwed up the filters prior to them they are likely just fine. Might need/want to run some cleaner in there at some point, but that'd be more because they're 20 years old rather than just the couple years they sat. I'd say run it first for a little bit, THEN change ALL the fuel system filters.

I'd be much more concerned with whatever gas supply has been in the boat and spend the bulk of my time with that issue.

Re: MPI vs carb

Posted: March 25th, 2021, 9:29 pm
by turin0905
Thanks to all. We are going to keep running with the fuel injectors and re-built both engines.