Fuel Injected vs. Carbed Mercruiser

[jjt98]

The fuel injected Mercruiser is prefered over a carbed version right?

What year did they start putting fuel injection on the Mercuiser? My list of boats to buy is down to two now. One has '95 5.7 Mercuiser and the other an '98 5.0 Mercuiser. Both around 400 hours.

 

[Uraijit]

Re: Fuel Injected vs. Carbed Mercruiser

Both of those boats should have had EFI as an option. But even now, they're still making them with carbs.

The only way to determine whether or not your boat will have EFI, is to make sure it does before you buy it.

All else being equal, go for the 5.7.

 

[arks]

Re: Fuel Injected vs. Carbed Mercruiser

The fuel injected Mercruiser is prefered over a carbed version right?

Well, maybe. I might get flamed for this, but the EFI engines are computer controlled, which means that any problem or performance adjustment will need professional diagnostics (BIG $$$$$). A good old carb can be adjusted (and rebuilt) by anyone with a little knowledge, including a lot of "shadetree" mechanics. In the past, I've been able to successfully make it home with a carb motor by making some adjustments; can't do that with EFI.

Short story: About 8 years ago I decided to repower a boat I owned. She had a stock Merc 260 (5.7) carb. The new engine was a brand new crate Merc 5.7 EFI. It was completely installed by a certified Mercruiser dealer. While cold starts were much easier, I found absolutely no performance difference between them. Even fuel economy didn't change. I felt it was money wasted- especially since a major problem developed with the engine. It (fortunately) was covered by warranty because the dealer spent probably 30 hours trying to diagnose the problem. They finally found the ECU was defective when warm. Just the part cost $700. OUCH.
Sold the boat the next season because I didn't want to deal with the @&%* computer controls. The ENTIRE reason I put in that engine was for reliability, which it did NOT have.
My current boat has twin V8 carbureated Crusaders and I couldn't be happier. Not a lick of trouble for the past 4 years.

What year did they start putting fuel injection on the Mercuiser?

Uraijit's right- my new engine was a 2000 and I remember by that time they offered a couple different carb models as well as 2 EFI versions (TBI and MPI).

 

[mylesm260]

Re: Fuel Injected vs. Carbed Mercruiser

All things being equal, I would much much much prefer EFI over any carb.


Mainly because an injected motor will behave much more predictably that a carbed motor. While it's true that a well tuned carb can get similar power and fuel economy to EFI, Carbs easily fall out of adjustment, and all the complicated linkage can gum and bind and bend, which results in unpredictable behavior. Carbs also have greater risk of fire, as you have fuel stored in the carb which could leak down into the electrical components and ignite.

While EFI systems can be harder to diagnose and repair than a carb, I believe they are generally more reliable and certainly more predictible. I"m running automotive EFI in my boat, so I can connect my OBD-II scan tool to my ECU and find any problems easily. (I always have O2 sensor fault codes, because I don't have any)

If your 4 main sensors are working, and you've got fuel presure and clean fuel, an EFI boat will always start and idle better than it's carbed counter-part. And will always get consistant fuel economy and power.

EFI also gives you computer controlled idle. Since I've switched to EFI, my boat has not stalled or stuttered once (2 years now) My carb would constantly stall while starting or trying to switch gears.

 

[Uraijit]

Re: Fuel Injected vs. Carbed Mercruiser

All things being equal, I would much much much prefer EFI over any carb.


Mainly because an injected motor will behave much more predictably that a carbed motor. While it's true that a well tuned carb can get similar power and fuel economy to EFI, Carbs easily fall out of adjustment, and all the complicated linkage can gum and bind and bend, which results in unpredictable behavior. Carbs also have greater risk of fire, as you have fuel stored in the carb which could leak down into the electrical components and ignite.

While EFI systems can be harder to diagnose and repair than a carb, I believe they are generally more reliable and certainly more predictible. I"m running automotive EFI in my boat, so I can connect my OBD-II scan tool to my ECU and find any problems easily. (I always have O2 sensor fault codes, because I don't have any)

If your 4 main sensors are working, and you've got fuel presure and clean fuel, an EFI boat will always start and idle better than it's carbed counter-part. And will always get consistant fuel economy and power.

EFI also gives you computer controlled idle. Since I've switched to EFI, my boat has not stalled or stuttered once (2 years now) My carb would constantly stall while starting or trying to switch gears.

Getting ready to install a TBI system over the fall. You can easily get rid of your O2 sensor codes by "deflagging" the o2 codes on the chip.

What system are you running? I don't have the hardware right now, but if you like, I can probably burn you a new chip before next season.

Let me know.

[/hijack]

 

[mylesm260]

Re: Fuel Injected vs. Carbed Mercruiser

I'm basically running the entire setup (engine, ecu, etc) out of an 01' astro van. I made a custom wiring harness my modifying the existing one.

21' Boat does 64 MPH (gps) with just me in it at about 4900 RPMS with a 23P prop

put 4 big boys in it and it tops out at around 55 @ about 4500.

The fault codes don't bother me. The ecu is running in open loop mode because. Well there is no way to run closed loop on a boat, it's an emmisions issue anyway. Because the motor uses an MAF, my a/f ratio is pretty close even with out the o2 sensors.


The only real issue it causes me is I have to hit the scroll down button a couple times to see if I have any other fault codes (which I don't)

If I blow this motor, I think I'm going to run the all aluminum 5.3L Same v8 bolt pattern, so I can still use my coupler and rear engine mounts. rated at 295 HP in the truck, it would proably make about 330 in a boat (improved exhaust flow) which is basically the limit of my alpha-1 leg anyway.

Not sure what my top speed with be with the extra power (roughly 100 more over what I've got) but it would make cruising must easier on the engine. (right now to cruise @ 40 mph I'm turning about 4000 rpms)

If anyone is thinking of a modern fuel injected automotive re-power, that 5.3 I think would make a wicked boat motor. It's based on the LS-2 (4 bolt mains, etc etc) they're bullet-proof engines and they can be had on ebay for 600 bucks.

 

[achris]

Re: Fuel Injected vs. Carbed Mercruiser

I'm basically running the entire setup (engine, ecu, etc) out of an 01' astro van. I made a custom wiring harness my modifying the existing one.....

None of which are MARINE rated... Pray you are never involved in an incident... Even if it's not your fault and doesn't involve the fuel system... The USCG will be all over your boat like a rash... see that fuel system and you will be in one large tub of very hot water... and kiss your insurance good-bye...

And I certainly would NOT be recommending an all aluminum engine for a boat!!! Do you have any idea what seawater does to ali? (obviously NOT!)

Chris........

 

[79Glastron]

Re: Fuel Injected vs. Carbed Mercruiser

I would say that if you were never around an engine with a carb, or know the quirks about them, I'd say make sure you have MPFI, or TBI.

 

[Uraijit]

Re: Fuel Injected vs. Carbed Mercruiser

I'm basically running the entire setup (engine, ecu, etc) out of an 01' astro van. I made a custom wiring harness my modifying the existing one.

21' Boat does 64 MPH (gps) with just me in it at about 4900 RPMS with a 23P prop

put 4 big boys in it and it tops out at around 55 @ about 4500.

The fault codes don't bother me. The ecu is running in open loop mode because. Well there is no way to run closed loop on a boat, it's an emmisions issue anyway. Because the motor uses an MAF, my a/f ratio is pretty close even with out the o2 sensors.


The only real issue it causes me is I have to hit the scroll down button a couple times to see if I have any other fault codes (which I don't)

If I blow this motor, I think I'm going to run the all aluminum 5.3L Same v8 bolt pattern, so I can still use my coupler and rear engine mounts. rated at 295 HP in the truck, it would proably make about 330 in a boat (improved exhaust flow) which is basically the limit of my alpha-1 leg anyway.

Not sure what my top speed with be with the extra power (roughly 100 more over what I've got) but it would make cruising must easier on the engine. (right now to cruise @ 40 mph I'm turning about 4000 rpms)

If anyone is thinking of a modern fuel injected automotive re-power, that 5.3 I think would make a wicked boat motor. It's based on the LS-2 (4 bolt mains, etc etc) they're bullet-proof engines and they can be had on ebay for 600 bucks.

Good luck finding an LM4 (all aluminum 5.3L), they're not NEARLY as common as the LM7 (Iron block). There really aren't that many advantages to the aluminum block either. With constant fresh cold water flowing through the engine, heat is not much of a factor, and weight wise, not going to make much difference on a boat. I'd save your bucks and just go with the LM7.

As far as the non-marine fuel injection system goes. Just don't be stupid. It's pretty hard to mess up fuel injection, but there are people out there who're stupid enough to pull it off. Use an oil pressure fuel shutoff relay, and use steel lines on the pressure side of the pump, and you should be just fine.

The ONLY concern I have is around the technicalities that everybody else mentions (IE, it doesn't have the "Coast Guard Stamp"). But that's exactly what it is; a technicality.

Now, starters, alternators, carbs, etc. Those are items that you should be making sure are marine rated.

 

[mylesm260]

Re: Fuel Injected vs. Carbed Mercruiser

For my fuel lines, I'm using hydrolic lines, With all professionally crimped ends/fittings, low pressure and high presure side of the pump. I checked with the manufacturer and they're rated for hydro-carbon fuels. You just have to be sure not to use teflon tape on the threads, instead use thread selant (permetex)

I'm sure a steel braded hydrolic hose rated for 3000 psi on a machine that bends and moves, will be more than adequate at 44 PSI not moving. Certainly a huge step up from what came out of my boat (old britle rubber hose)

And I'm in the process of installing an oil pressure and temp alarm system.


And you do make a good point about going with the aluminum motor. The cast iron versions can be had for cheap cheap cheap though, and I like I said, they're based on the LS-1 or LS-2... very tough motors...

And as mentioned, My starter and Alternator are marine, I've got a new blower motor that I leave on all the time. Even though my fuel injection system isn't "coast guard approved", my boat is just as safe, if not safer than anything else on the water (Except maybe a diesel)

And in terms of insurance, Well, I'm canadian and I don't need or have insurance! My boat is an 88 and only worth about 8K.

 

[Uraijit]

Re: Fuel Injected vs. Carbed Mercruiser

Sounds like you're covered on the fuel line end. But what you need to do, is have the fuel pump wired in so that it will not run the pump unless there is oil pressure. This prevents your electric fuel pump from draining your fuel tank into the bilge, in the unlikely event that you develop a leak somewhere.

Alarms are nice too, but definitely wire in the pump shutoff. Most car ECMs will shut off the fuel pump after a few seconds of the engine not running, but if yours isn't wired that way, it'd be a good idea to do it.

Not trying to be a ball buster or anything. I, like you, believe that your system can be just as safe, or safer than what's on any other boat out there, regardless of what stamps it has on it.

Oh, and my offer stands to burn you a chip. No charge. Just send it with a return envelope and postage paid.

 

[achris]

Re: Fuel Injected vs. Carbed Mercruiser

...

And in terms of insurance, Well, I'm canadian and I don't need or have insurance! My boat is an 88 and only worth about 8K.

Please tell me this is a joke... Not carrying insurance, just because YOUR boat's not worth much is very risky... What about if you're involved in an incident with something worth half a mill? No insurance, you pay sunshine! Think very carefully about that decision... I hope it doesn't come back and haunt you...

Chris...........

 

[Uraijit]

Re: Fuel Injected vs. Carbed Mercruiser

Please tell me this is a joke... Not carrying insurance, just because YOUR boat's not worth much is very risky... What about if you're involved in an incident with something worth half a mill? No insurance, you pay sunshine! Think very carefully about that decision... I hope it doesn't come back and haunt you...

Chris...........

That's why you don't boat like a jackass!

 

[achris]

Re: Fuel Injected vs. Carbed Mercruiser

That's why you don't boat like a jackass!

You don't have to be a jackass to be involved in an accident...

 

[APPALOOSA2]

Re: Fuel Injected vs. Carbed Mercruiser

I for one have never had a carbed Mercruiser ever just quit, never had a fire with a carb. Maybe because I'm mechanical and take care of my boats I've had over the years.
I do agree that with EFI you can have many problems that render the boat dead, sometimes in limp mode.

As far as auto compontents in a boat some things will work but when it comes to safety YOU better know what works 100% safe versus it should be OK....

My dad owned a marina and I still will never forget the sound, sight of boats that blow up and yes you are dead. When boats went to fiberglass and the bilge was then pretty airtight, that created a floating bomb. Most of the older wooden boats had enough air circulating to just go woof and burn but those glass boats just go boom...

Boats take quite a beating out on the water clamps loosen wires that are free move things happen !

I for one double clamp all my fuel lines and water hoses, I have seen clamps break, rare but it does happen.

I for one don't use my bilge blower, I lift the hatch first ,look and smell then I will put the blower on and go the vent and smell. Sounds rediculous but not to me who has seen it with there own eyes what happens with just a little gas leak.

Oh and one more thing, I love people who keep the fire extinguisher by the engine compartment that is now on fire !

 

[mylesm260]

Re: Fuel Injected vs. Carbed Mercruiser

Alarms are nice too, but definitely wire in the pump shutoff. Most car ECMs will shut off the fuel pump after a few seconds of the engine not running, but if yours isn't wired that way, it'd be a good idea to do it.

Yeah, My ECU pulses the pump for 2 seconds after you first turn on the ignition, then only turns it on again when it sees and ignition (spark) event. Just like it would in a car. Initially when you mentioned oil pressure, I thought you were talking about engine damage, but now that you explained it, it makes more sense.

And don't worry about ball busting, safety certainly takes priority over pride.

If you want to do some ECU flashing, I just picked up an 09 cobalt SS turbo that could use some more HP =)


Oh, and half the boats in canada don't have insurance, don't know why, just the way it is. In fact, I take my boat to washington state sometimes without insurance, and I've been stopped by search and resucue before (Safety / soberiaty tests) and they never mentioned a thing.

As far as auto compontents in a boat some things will work but when it comes to safety YOU better know what works 100% safe versus it should be OK....

Well, put it this way, That EFI system was used on every blazer, chevy van, chevy S-10, and half ton pickup that came with a V-6 for about 12 years.

And while the risk of fire is LOWER in a car/truck, it still happens (honda just recalled their CRV for risk of fire from a leaking oil filter) If there was ANY flaw in the design that allowed for fuel to leak into the engine compartment, it would be known by this point. More specifically, if you know the specific setup of the injector system (GM calls it their "pop-it" injection, the injectors are all actually INSIDE the intake manifold) you would know it's pretty fail-safe.

Boats take quite a beating out on the water clamps loosen wires that are free move things happen !

I for one double clamp all my fuel lines and water hoses, I have seen clamps break, rare but it does happen.

I'm using EFI clamps on the engine side (solid stainless with theaded screws, not the standard "slotted band" clamp). And All the other fuel fittings are 3000 PSI hydrolic fittings with professionally crimped ends.

I for one don't use my bilge blower, I lift the hatch first ,look and smell then I will put the blower on and go the vent and smell. Sounds rediculous but not to me who has seen it with there own eyes what happens with just a little gas leak.

That's not a bad idea.

Please tell me this is a joke... Not carrying insurance, just because YOUR boat's not worth much is very risky... What about if you're involved in an incident with something worth half a mill? No insurance, you pay sunshine! Think very carefully about that decision... I hope it doesn't come back and haunt you...

Chris...........

Well, I honestly never really thought of it that way. I can't imagine any scenerio where my boat or my driving would cause damage to another vesel, but hey I guess anything is posible. Maybe I will get insurance... I know it's not even that expensive (here anyway) My insurance agent mentioned it when I insured my trailler.


On open water, I try and stay 100 feet away from any other boat.... and when docking, I take it slow and easy.... (just like everyone else, I'm assuming)