EFI vs Carb?

Gasoline powered boats need carbs.

EFI is great for cars, but have no place on a boat.

EFI on a boat starts out pretty good, if its installed properly.

Soon, however, everything starts to deteriorate, a tiny bit at a time, and at different rates. Just like everything on every boat.

What happens with marine EFI is that it then becomes simply a GIGO machine: garbage in, and garbage out. All those sensors feed in to the EFI computer: air density and temperature, fuel pressure, knock, water temperature, voltage, fuel flow, etc. etc.

The computer takes all this input, and then adjusts everything: ignition timing, fuel flow, throttle position (yes, even on old EFI engines, the mechanical throttle is just a resistor read by the computer, and the computer adjusts the butterflys).

See the problem? If one or many of the sensors start to be a bit off, and/or one or many of the actuators start to be a bit off, and/or any of the wires between the sensors, computer, and acutators are corroded, then the computer is reading bad data, applying it to its internal algorithms as if everything is perfect, and then misadjusting the engine due to the poorly performing acuators.

Try to track those problems down! It really can't be done. Your EFI engines basically become displosable.

True, you can buy analysis software that runs on your laptop, and you can simply plug your laptop into the harness. Very easy. However, the software just dumps out all of the data for you: you can watch all those sensor values and actuator values jumping all around as you drive around. Very impressive! Fascinating! But its all data, no information. What should any of the values be? No way to tell. Even if you could tell that, say, there is too much spark advance, can you tell why? No! Can you tell what to do about it? No!

The good thing about having Mercruiser EFI, was I ordered new wiring harnesses from Mercury -- just gave them the serial numbers for the engines and $800 per engine -- and they plugged right in. Not as easy as it sounds -- took about 15 hours of hard labor on each engine to get the old ones removed and the new ones installed.

And now I'm back to almost like new.

How much did it cost? About $10,000 to Bob Teague of Teague Custom Marine to not be able to fix the problem. Not all at once, but over many times in his shop. Then another $7000 to Paul Pfaff to not fix the problem. Again, many expensive attempts without solution. Then finally another $4000 to Paul Pfaff to re-wire, and that fixed the problem. I had to tell them to do it, they could not tell that was the problem. In all, well over $20000 to fix the EFI problems due to decaying electricals.

That is a little less than how much fuel I have burned in the boat, but not a lot less.

So EFI would have to double the mileage to even be worth considering over carbs.

 

Good post U4,-- exellent.

 

The only exception would be an aftermarket Fuel Injection and electronic ignition that is simple like the Edelbrock system for Chevy/Mercruiser type V8 or V6 .But yes generally speaking carbs, easier to keep working.

 

Great thread, thanks.

I'm ordering my new outboard today and out here I still have the option of good old fashioned Yamaha carb or direct injection, not for much longer I guess.

Anyway this has just reinforced what I was thinking. Stick with the simple technology I'm used to