1993 Mercruiser 350 w/carb, able to change EFI?

[samm835]

I have a Mercruiser 350 in my boat with around 350 hours, she runs great but I am thinking I would like to add EFI to it. Has anyone done this before, was it easy to yourself and what was the rough price of doing it? I am fairly mechanical....so I prefer to save some $$$$ and do myself if at possible.

 

[alldodge]

Folks have done it, but its costly unless you can find a donor motor which has a cracked block

 

[Lou C]

Ask yourself just what advantage will you get, vs cost and possible unavailability of EFI parts for older engines. I can't see it being it worth it no matter how you look at it. The only advantage is better running when cold, and more reliable starts. But a well tuned and clean carb will do well enough. Both Merc and Volvo have a lousy habit of making certain EFI parts NLA after 10-15 years then you are stuck. That won't happen with a carb because of the aftermarket.

 

[Scott06]

Why won’t make much more power or better fuel use. Best way to do this upgrade is keep the trailer put an efi or mpi boat on it. Seriously not worth the cost buy a newer boat with it already unless you are looking for something to do and ways to spend money.

 

[QBhoy]

As far as I know this would be a waste of time. If you already have a 250/260hp 5.7 carb...an efi 5.7 is the same power I’m sure. If it’s to save fuel...the difference is minimal on an efi. It would take you years to offset the bother and cost of doing it.

 

[Lou C]

You'd never save fuel. What you would get is an engine that runs more smoothly and reliably when cold, which is an advantage in a boat where you can't use a fast idle system, but that's really it. So the benefits are in getting the boat off the trailer, or away from the dock with a cold engine but after the engine warms up, its not that much of a benefit. To me the biggest downside is parts cost and parts availability.

 

[achris]

I have a Mercruiser 350 in my boat with around 350 hours, she runs great but I am thinking I would like to add EFI to it. Has anyone done this before, was it easy to yourself and what was the rough price of doing it? I am fairly mechanical....so I prefer to save some $$$$ and do myself if at possible.

First off, why do you wish to change to EFI?

When I had my 4.3LX it had the notorious dribbly Weber problem, and restarts were a PITA. I researched many many different options for change to EFI, including an EFI specialist looking at the engine and quoting on doing the job. It didn't matter which way I looked at it, the cheapest option, and the option I ended up going with was to sell the 4.3LX and buy a brand new 4.3MPI...

There is no cost effective way to convert a current carbed (marine) engine to EFI...

Chris.......

 

[samm835]

I guess I should have posted that there is no real reason why I was thinking about changing.....other than cold start. I knew I wouldn't save gas, and wasn't trying to. She runs great, starts fine.......so it looks like I will be keeping what I have. Thanks, I can find other ways to **** away my money. lol

 

[Bondo]

.....other than cold start.

Ayuh,....... What's yer procedure for a cold start,..??..??

Maybe we can fix that,........

 

[Scott Danforth]

exactly, list exactly what you do for a cold start

what you should be doing.....

one to two full pumps (the first sets the choke and primes the system. the second may or may not be needed for an extra shot of fuel to prime)

then press the throttle only button and move the lever to about 1/4 throttle, and turn the key. your motor should start and be about 1000-1500 RPM, then back off the throttle to about 1000 RPM for a few mintues, then go boating.

if that doesnt work, your choke may need adjusting

 

[Lou C]

It helps if you learned to drive in the late 60s early 70s and all of our cars had auto chokes and each one was a little different. My Quadrajet needs 3 pumps full throttle then set it back to 1/3 throttle and crank it over and starts right up. But of course we had a car with a Quadrajet too!

 

[achris]

I remember when an automatic choke was a 'new fangled' thing. When I was growing up, all cars had a 'choke knob'. You pulled that out when starting a cold engine... :facepalm:

 

[Scott Danforth]

I remember when an automatic choke was a 'new fangled' thing. When I was growing up, all cars had a 'choke knob'. You pulled that out when starting a cold engine... :facepalm:

And even today, 50 to 60 years later...... It would still start

 

[achris]

And even today, 50 to 60 years later...... It would still start

No denying that.

 

[Lou C]

Ever watch millennials try to start a 2 stroke blower or weed wacker?