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cyclops2

Which is easier to inspect, adjust & maintain the correct fuel mixture? F I or carb. ?

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It is all about having th right tools and knowledge. I can get my boat running or at least diagnose it when it fails anywhere. I have a 5.0L MPI. I also have the Diacom tunning software and Merc scan tool. I keep them under the passenger seat in a waterproof case.

I have been working on EFI since it's inception. The fact of the matter is, if you understand a carb you can understand EFI, also vice versa, if you do not understand fuel delivery you will not understand either device, one is just easier to tinker with because it takes a 25 cent screw driver as compaired to 200 deer software.

The EFI on boats is a huge improvement even though it is Open loop (meaning it does not have o2s correcting the air fuel ratio). Yes it is batch fire, which is not throwing fuel away. The cylinders not firing are getting a cool down shot, which cools the intake valve, that fuel mostly evaporates, then when the intake valve opens what is left is added to the mixture and if the inline is tuned well it is accounted for in the volumetric efficiency tables.

Another huge advantage to EFI is the fact it controls the timing. It controls it based on engine RPM and load via a map sensor whhich reads vacuum. So like battleship it has vacuum and RPM and uses this to pic a timing value. The nice thing about EFI is the timing map does not have to be linear as it is with a vacuum, advance and weights, thus you can dial up different timing during different cruise conditions to take advantage of your fuel and power. For instance at 3000 Rpm on a calm day no wind, you have little load on the boat, the fuel can be dialed back and the timing retarded, but 3000 Rpm into waves and a head wind, and you can advance the timing and pour the coals to it to keep things headed in the right direction. Basically at 3000 rpms you can have multiple operating conditions based on a nonlinear map for fuel and timing based vacuum and Rpm. Th advantage to EFI.

The next big thing is temperature compensation. Based on coolant and air temperature, the fuel and timing can be altered. This means when it goes from 90f summer afternoon to a 60f night cruise home the engine will compensate the fuel delivery based on air temp and engine temp. This is particularly useful on a cool night starting a hot engine as it can compensate the fuel to get things running smoothly. On a carbed engine this is tricky cause the choke is deactivated due to a hot engine, but the air is denser commanding a little more fuel.

Carbs can be made to run well, there is no doubt about it. They are an effective means of fuel delivery. They can be setup to deliver the same or more power, they can probably be setup to give you max fuel economy, but what they have trouble doing is giving you max power, max fuel economy, and drive ability in all conditions consistently. EFI gets you closer to this. New engines with closed loop EFI and sequential injection, get you this in a big way!

And if anyone wants to compaired fuel burn and power numbers, I would be happy to. I have them data logged on my laptop and my current tune is quite impressive, and I did it myself.

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I think we have succeeded in wandering away from the original question ???????

Can .....ANY OF US.......adjust the idle speed , idle fuel / air ratio..........Put a credit card over a none running lean running engine & motor home if alone & out of radio range for help.

I have been told by boat & auto dealers I have to wait for help. Is that true since 2002 ? That is the only reason I bought a carbed engine. Does any F I system Have a manual bypass system for boats ? I can not step out of the boat & walk to help like a car breakdown.

Hope this gets us back to what I was trying to ask about.

Rich

MPI brake-down too. It's just a completely different approach to diagnosis and a new skill set to be learned. In the end, the core issues remain the same. Contaminated fuel, bad fuel pump, low battery voltage. It is rare that you loose a sender, but Guardian Mode allows you to limp home in almost all cases. Ignition modules are pretty bullet proof, but late model Carb'ed engines have them too.

Talk with the SeaTow and Boats US boys and ask what they see. Overheating because somebody ran over a trash bag, or pushed a raw water impeller too many hours. Dead batteries from being on the hook too long. Busted out drive due to using your skeg as a depth finder. Out of fuel. Then ask you Merc dealer how many ECM's he's sold over the past 10 years. Injectors are expensive, but if you feed them right, they live. Clean, inhibited fuel. Fog the engine per MPI guidelines, and sensors tend to live too.

W

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The only good fuel injection installed on a boat engine is what's on the Volvo 380.

My carb'd engine has computer controlled ignition with a rev-limiter (TB5). Had to get towed home 3 weeks ago when the module went bad.

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The 496 8.1 liter engine has never. Ever. EVER. Been installed in a boat, car, motorcycle, gokart, scooter with a carburetor. To say the "496 crowd" with carbs is having trouble is bull@#$%@# because there has never been a vessel powered in the history of mankind that has rolled off the factory floor that has ever been powered by a 496 with a carburetor.

Keep reading. I follow this stuff close and was a General Motors Master Tech in NJ back in the day. There were 5 of us that year, and I've had my hands in more of these engines than I care to remember.

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Honestly, I can set my idle speed, timing, and fuel mixture very easily, on my EFI boat, and I have it all on one screen so I can see how one effects the other and make changes accordingly, then I can save the calibration, and make a completely different one if I want to and then load them in less than five minutes.

I also can look a togs of my RPM run time and temperature data to make sure nothing has gone of the rails.

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It is all about having th right tools and knowledge. I can get my boat running or at least diagnose it when it fails anywhere. I have a 5.0L MPI. I also have the Diacom tunning software and Merc scan tool. I keep them under the passenger seat in a waterproof case.

I have been working on EFI since it's inception. The fact of the matter is, if you understand a carb you can understand EFI, also vice versa, if you do not understand fuel delivery you will not understand either device, one is just easier to tinker with because it takes a 25 cent screw driver as compaired to 200 deer software.

The EFI on boats is a huge improvement even though it is Open loop (meaning it does not have o2s correcting the air fuel ratio). Yes it is batch fire, which is not throwing fuel away. The cylinders not firing are getting a cool down shot, which cools the intake valve, that fuel mostly evaporates, then when the intake valve opens what is left is added to the mixture and if the inline is tuned well it is accounted for in the volumetric efficiency tables.

Another huge advantage to EFI is the fact it controls the timing. It controls it based on engine RPM and load via a map sensor whhich reads vacuum. So like battleship it has vacuum and RPM and uses this to pic a timing value. The nice thing about EFI is the timing map does not have to be linear as it is with a vacuum, advance and weights, thus you can dial up different timing during different cruise conditions to take advantage of your fuel and power. For instance at 3000 Rpm on a calm day no wind, you have little load on the boat, the fuel can be dialed back and the timing retarded, but 3000 Rpm into waves and a head wind, and you can advance the timing and pour the coals to it to keep things headed in the right direction. Basically at 3000 rpms you can have multiple operating conditions based on a nonlinear map for fuel and timing based vacuum and Rpm. Th advantage to EFI.

The next big thing is temperature compensation. Based on coolant and air temperature, the fuel and timing can be altered. This means when it goes from 90f summer afternoon to a 60f night cruise home the engine will compensate the fuel delivery based on air temp and engine temp. This is particularly useful on a cool night starting a hot engine as it can compensate the fuel to get things running smoothly. On a carbed engine this is tricky cause the choke is deactivated due to a hot engine, but the air is denser commanding a little more fuel.

Carbs can be made to run well, there is no doubt about it. They are an effective means of fuel delivery. They can be setup to deliver the same or more power, they can probably be setup to give you max fuel economy, but what they have trouble doing is giving you max power, max fuel economy, and drive ability in all conditions consistently. EFI gets you closer to this. New engines with closed loop EFI and sequential injection, get you this in a big way!

And if anyone wants to compaired fuel burn and power numbers, I would be happy to. I have them data logged on my laptop and my current tune is quite impressive, and I did it myself.

+1

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Okay you do know that the 496 in your boat bares no resemblance to the 496 from the 1960's right?

:slap:

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Okay you do know that the 496 in your boat bares no resemblance to the 496 from the 1960's right?

:slap:

Time to give up on you.

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Marine Engines: EFI vs. Carbureted Models

April 11, 2013 By Brett Becker

Say you’re looking at two lightly used runabouts with Volvo Penta propulsion. One is a 2011 model with a base 4.3-liter V6 with 50 hours on it. The other is a 2012 model, also with a base 4.3-liter V6, but this one has 100 hours on it. They’re listed for the same price. Which one do you buy?

The one with lower hours, of course, right?

Not so fast.

In 2012, Volvo Penta did away with carburetors on all its engines, so in this case, you likely would be better off going with the boat with more hours on it.

Why? Fuel injection rules. The superior operating characteristics, the lack of maintenance, and the abbreviated winterization make it the better call. EFI also is safer because the sealed fuel system stands much less chance to leak or spew fuel vapors under the hatch in the engine compartment. What’s more, the 2012-and-up Volvo Pentas also feature electronic throttle control and advanced engine monitoring systems.

“For many years, a low-horsepower engine was a boater’s first experience with a sterndrive boat,” said Clint Moore, President and CEO of Volvo Penta of the Americas in the initial press release. “Times have changed. As with today’s car buyers, a new boater is more knowledgeable than ever before, with understandably high expectations. We believe those expectations are only met by higher-horsepower, more technically sophisticated engines. We build the engines that are designed to keep people in boating.”

The move away from carbureted engines was long overdue, and not long after Volvo Penta kicked carburetors to the curb, MerCruiser began offering EFI on its entry-level 3.0-liter four-cylinder stern drive engines. Hallelujah.

The reality is that marine engine companies no longer need to create their own EFI systems because fuel-injection technology is so abundant. They only need to adapt what already exists, and there is enough sales volume in the marine market to justify it.

“Our decision to exit the low-horsepower, carbureted engine market allowed our engineers to focus their energy on creating state-of-the-art propulsion packages designed to deliver great boating experiences, even at the entry level,” Moore said.

http://blog.boattrader.com/2013/04/marine-engines-efi-vs-carbureted-models.html

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Cyclops,

Your question is a bit loaded and you're obviously trolling for an opportunity to tout "the good old days" and to us boaters that have embraced modern technology, those days don't seem so good.

First, the average boater doesn't have the ability to inspect, adjust, and maintain either fueling system, so the question really doesn't apply to them. If you know how to tear apart and rebuild a carb, good for you, but that you don't possess or have the ability to operate diagnostic software required for modern fuel systems does not suggest that a carburetor is better choice in fueling.

Second, you've clearly overlooked, or simply don't understand, the most prominent advantage of fuel injection: there's virtually no inspection, no adjusting, and no maintenance to be done on a fuel injection system. Then there's the second advantage - ease of use. The average boater barely remembers what a choke is - hence the TKS systems. But even then, the average boater is too impatient for a carb'd engine to warm up properly. And then you've got the whole dieseling thing that carb'd engines tend to do...

Like it or not, carbs are going the way of the dodo bird. Modern emissions requirements are to strict for carbs to work.

My boat may have a primitive throttle body injection system, but after 600 hours of use, it still starts on the first turn of the key, idles smoothly, and runs perfectly. The idle has never been adjusted, the injectors have never been cleaned, and the ECU has never failed.

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Furthermore, did you ever stop to think that maybe the reason you see more fuel injected fueling issues reported to this board might be due to the fact that there are far more fuel injected boats out there than there used to be?

Heck, if this board was around 15 years ago, I bet you'd see the opposite - far more carburetor issues being reported than fuel injection issues.

Lastly, people tend not to post about an uneventful day. So of course you're only going to see poor running issues posted. The thing with fuel injected boats is that there is an alarm that tells the average person that there is something wrong, but not exactly what is wrong, so they get confused and post about it. With a carb'd boat, the only thing the average boater knows is that the boat doesn't run and it's time for a trip to the dealer. They're not going to report it here.

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That article is garbage.

Fuel injection didn't magically appear in 2012. Boats have had fuel injection for 20 + years.

The fuel system is not sealed on a fuel injected boat, no more than a carb'd.

The 3.0 went fuel injection for emission reasons not any other.

Not all 2012+ engines have electronic throttle control.

THE MARINE INDUSTRY NEVER DEVELOPED THEIR OWN FUEL INJECTION. General Motor's engines use General Motor's fuel injection. It's not marine specific. In fact, all GM Performance crate automotive engines use MEFI!!!!

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People read the internet and believe all is fact. Someone just a few posts above posted one with BOLD lettering as if they were making a point.

Almost everything in that article is false.

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kinda reminds me of the old saying....

"Better to remain silent and be thought a fool than to speak out and remove all doubt."

Abraham Lincoln

I don't think Ric gets it. Pretty sure the Lincoln quote is specifically aimed at him.

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Fuel injection didn't magically appear in 2012. Boats have had fuel injection for 20 + years.

Where in that entire article did you read that it said fuel injection magically appeared in 2012?

It said:

In 2012, Volvo Penta did away with carburetors on ALL its engines and not long after that Mercury began offering EFI on its entry level 3.0 liters. This is true, no? Why did you change the words and bring up "magically appearing in 2012" and "20+ years" when that was never mentioned whatsoever in the content?

Oh, and btw, that "someone" you mentioned above posting that article is me, you can call me out by my name it's ok. I highlighted those quotes because they were relevant to the discussion at hand.

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Well, I don't know too much about carbs. Sure, I can unstick the choke, set the idle, etc. Never rebuilt one. Don't know much about my MPI either, but I did manage to diagnose (thanks to the beeping) and change my IAC earlier this year. My MPI does run alot smoother than my carb did. No lag when I hit the throttle and it's ready to go seconds after it's started.

I DID, however, stay in a Holiday Inn last week. :oregonian_winesmiley:

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There is less exposed fuel in an MPI system. The fuel goes from the injector to the back of the valve. You would be hard pressed to even see it happening unless you looked into the throttle body just right. With a carb you can take the air cleaner off and it is right there for you to witness.

The Mercruiser EFI uses GM hardware but it is not GM programming, I have about every tool there is to crack GM code from the early vortecs to the latest E38 ECMs. It does not work on the MPI ECMS on the boats I have tried. Thus the reason I purchased the Diacom software. Mercruiser is running some sort of proprietary operating system.

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My 2002 5.0 L carb has 190 ? hours.

Sounds like you need to stop b¡thing about fuel injection and start driving your boat.

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DAVECS1

Thanks for the practical answer to my question. I stirred up this hornets nest to see to see if there is a way for me to check & if needed figure a " get around " for a isolated area problem that could be done to limp home .

I asked because I will be buying a new / very new muscle engine boat.........Be back

Rich

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There is less exposed fuel in an MPI system. The fuel goes from the injector to the back of the valve. You would be hard pressed to even see it happening unless you looked into the throttle body just right. With a carb you can take the air cleaner off and it is right there for you to witness.

The Mercruiser EFI uses GM hardware but it is not GM programming, I have about every tool there is to crack GM code from the early vortecs to the latest E38 ECMs. It does not work on the MPI ECMS on the boats I have tried. Thus the reason I purchased the Diacom software. Mercruiser is running some sort of proprietary operating system.

I'm glad somebody at least tried to use an automotive brick to read a Merc ECM. I bought the Merc tool also, and then had to spend another 75 beans for the "special cable" in order to access the PCM-555 processor. Turns out the 496 HO's use the PCM-555 brain, and the standard 8.1's use the ECM-555, as do some of the high output small blocks. The PCM comes out of the Merc racing division and I like the way it stores a histogram relative to previous alarm codes. When my friends go used boat shopping, I take my brick along. Do you have the ECM Merc manual for your ride? If not, let me know what brick you have and I just might have a PDF file. W

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Well, I don't know too much about carbs. Sure, I can unstick the choke, set the idle, etc. Never rebuilt one. Don't know much about my MPI either, but I did manage to diagnose (thanks to the beeping) and change my IAC earlier this year. My MPI does run alot smoother than my carb did. No lag when I hit the throttle and it's ready to go seconds after it's started.

I DID, however, stay in a Holiday Inn last week. :oregonian_winesmiley:

:clapsmiley:

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There is less exposed fuel in an MPI system. The fuel goes from the injector to the back of the valve. You would be hard pressed to even see it happening unless you looked into the throttle body just right. With a carb you can take the air cleaner off and it is right there for you to witness.

The Mercruiser EFI uses GM hardware but it is not GM programming, I have about every tool there is to crack GM code from the early vortecs to the latest E38 ECMs. It does not work on the MPI ECMS on the boats I have tried. Thus the reason I purchased the Diacom software. Mercruiser is running some sort of proprietary operating system.

I'm glad somebody at least tried to use an automotive brick to read a Merc ECM. I bought the Merc tool also, and then had to spend another 75 beans for the "special cable" in order to access the PCM-555 processor. Turns out the 496 HO's use the PCM-555 brain, and the standard 8.1's use the ECM-555, as do some of the high output small blocks. The PCM comes out of the Merc racing division and I like the way it stores a histogram relative to previous alarm codes. When my friends go used boat shopping, I take my brick along. Do you have the ECM Merc manual for your ride? If not, let me know what brick you have and I just might have a PDF file. W

You two share some great info. Thanks!

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