Fuel Injection

I too am interested about what issues you are seeing because of the carburetor?

Also, a classic case of points are bad and EI is good. Points set up properly will run exactly the same as an EI conversion.

Thank you all for the input, and please keep it coming!

For the most part, it runs well. Maybe I should upgrade my fuel filtration because my problem is typically resolved by tearing down the carb, cleaning it out really well, and putting it all back. Any small particulate in an emulsifier tube, jet, fuel passage, etc., will cause performance issues. A good cleaning resolves it. But I don't want to do that anymore. Of course, I know I would need to include a quality filtration system with an EFI install because injectors can clog as well.

I always have cold start issues and idling has been troublesome lately. The hand -held squirt can of gasoline might work for some of you, but if the accelerator pump on your carb is functioning properly, you shouldn't need a squirt can of gasoline. The accelerator pump does exactly that; it's a built-in squirt can!

This motor used to idle at 450-500 rpm with no problem. Lately, it will stall below 800. That's not so nice during my evening put-put cruises around the lake. I've played with the idle circuit and timing, but I can't seem to find that old sweet spot. She's old, I know, and that's why I wanted to try something new.

Aftermarket systems like AFI and Howell seem great because they are all self contained and I won't have to piece together a Frankenstein EFI. They will work with my current ignition also, but I would upgrade that if it was helpful. In fact, i was unaware of the Motec unit suggested above by UK1979 - I'll have to learn more about that.

Another key aspect to some of these aftermarket systems is that they do not require an O2 sensor; it's optional. Although there is an ideal location in my exhaust that I could add an O2 sensor, I would try it without first.

It does not surprise me to see the "no ethanol" warning label on your 1995 EFI system. Ethanolized fuel was not mandated back then and the fuel systems were not designed to handle ethanol. In New Jersey, it is illegal for gas stations to sell non-ethanolized fuel.
I can buy non-ethanol fuel in 32 oz. containers at the auto parts store and the cost is astronomical. Can you imagine filling up your boat with one quart containers!!! All our small engines, in fact, like your weedwacker, lawn mower, snowblower, etc., do not like ethanol either. Ethanol sucks, but we are stuck with it for the time being.

Overall, it sounds like none of you have made such a conversion to EFI on your boats. That makes me a pioneer in addition to a newby!!! Wish me luck.

Also; stabilizer products that some of you suggested above don't actually resolve the ethanol problem in our gasoline. They may help extend the fuel's lifetime while it's sitting in your tank, and I do use them myself, but they don't 'remove' ethanol and they don't stop the ethanol from damaging fuel system components. The ethanol is still there.

Besides damaging fuel system components, the ethanol is hygroscopic; it loves to suck up moisture from the air. Like most of you, I use my boat in the water (I hope you're laughing), so there is plenty of moisture around for the fuel to suck in through your fuel tank vent. I don't know that this problem is avoidable in any way, regardless of additives, other than burning fuel as quick as you can. Lucky for us, burning fuel is fun!

My understanding of how products like Stabil work, and I could be wrong, is that it slows down the absorption of water by the ethanol, but it cannot stop it. In the good ole days, you would fill your fuel tank to the top before storing it for the winter. Now, you should drain it completely. That's because of the ethanol and it's propensity to absorb moisture.

Did I day ethanol sucks?

Kenvan, I totally agree with your opinion of ethanol fuel. After purchasing numerous replacement power tools I now exclusively use non ethanol fuels for my boats and small engines. I just bought a 2018 Yamaha VMAX 115 hp engine for my pontoon and Yamaha also recommends avoiding ethanol fuels.
i wish you success in your pursuit of an EFI system.

I don't get it. I rebuilt the carb of my other boat because it sat and was never used. Since I rebuilt it, I have put 600 hours on the boat. I use ethanol fuel because the non-ethanol places around me I would not even piss in their toilet. The clean, reputable gas stations sell gas with ethanol in it. The marinas only got non-ethanol fuel this year, so that was not an option. I have had 0 problems.

My 85 Ski Nautique burns all fuel equally, with no discrimination. It doe snot seem to care about about octane or the addition of alcohol. Again, I avoid the gas stations that advertise 100% gas but look like crap preferring a shell or bp with ethanol mixed in.

I just don't get why anyone has issues with an >= 80 percent gas mix.

Maybe you should change gas stations.

Also, good luck with the FI. Please document what all you do.

Ken I would love to see you do it and document it. One of the tricky tasks I think is going to be cleanly mounting your O2 sensors. I have thought long and hard about that because I would love to do it to mine. and have an idea if you want to be my Guinea pig. Send me a set of fresh unused risers and I'll try my ideas for O2 sensor modification out on you first.

Ken - what is the compression on your engine?

If not healthy, that could be a factor in your engine's poor idle performance.

Also, what do you have the timing set at?

So much to reply to in this post I don’t know where to start.

EFI conversion is literally the proverbial rabbit hole.
Fast makes a system but it’s $2K. All the others aren’t certified.
That said, all you really have to do is follow the USCG rules. It’s not brain surgery, just tedious. Little things like not putting the fuel pump in the tank,

Buy a OMC or Penta 302 like somebody mentioned. Parts are scarce and nobody likes them but if you’re a Mustang fan you’ve already got the knowledge.

Gary S- I see your collecting parts and raise you a Custom modified Edelbrock Manifold with BBK 70mm throttle body and a K&N Spark arrestor off a 502 Merc.

I have a carbed boat that generally runs great and always starts and runs and the carb hasn't been off in years - the holley black or blue electric fuel pumps however that I chose during the time I upgraded the engine past the point where a stock mechanical pump would feed it never seem to last more than 2 years - I would say that I have spent $1500-2000 on those over the past 10 years.   Moral of the story is that sometimes its not the sexy part of the upgrade that costs you money in the long run.    

Actual fuel injection systems are generally much safer than any marine rated carb - some care has to be taken in supporting systems as mentioned above with the fuel pumps/lines and the ignition components but injectors/throttle bodies etc are much less likely to dump fuel into your bilge than a carb. Current fuel injected marine engines are 99% direct automotive content - just the support systems are designed by the marinizer.   Those tend to be the parts that get to be expensive, hard to come by and are not tested and refined nearly as well as parts that have automotive volumes.

As for marine rated - IMHO its like they say on the picture tubes as long as you know the rules and why they are there you can break them.   Biggest issue for me and the fuel injection tends to be cost - for me to put in a couple k- I would definitely want a system with sensor feedback - ideally O2 and knock sensors and the ability to control the ignition curve as well as fuel delivery and even then I would only consider it on a boat that needed a new distributor and carb. 2k generally would be better spent on fancy cylinders heads(1st) or roller cams (2nd).   Unless I was spending other peoples money then even a static mapped stand alone throttle body system would be a fine upgrade.

you pays your money and you takes your choice - just be sure to post back here when you are done to tell us how it worked.