Unburned fuel

[vintin]

I’d like to point out that I’m a rookie at this antique and classic outboard motor stuff. Please don’t take my photos and explanations of how I perceive this stuff to work as me presenting myself as an authority. I’m not. I’m here to learn and have a good time.

Chris P., I like your way of routing the recovered fuel back to the tank and hiding it. I do have a question though as to what happens to the vaporized fuel/air mix. I’m not fond of it just being exhausted into the back of the boat after being forced out of the tank vent. It may be both a fire and lung hazard. It does seem feeding it back into the motors air intake system has some merit.

[PugetSoundBoater]

I like the idea of collecting the unburned mixture and reusing it. But after looking at the photo of the collected mixture in the clear container it looks most likely a higher percentage of oil than the original mix. This would throw off your oil:gas ratio considerably after adding it back into your tank,and add to the issue you are trying to solve .
I really try to get my fuel oil ratio close to exactly the recommended ratio ,and a slight bit more,to compensate for Seafoam and fuel stabilizer added to the gas. Not knowing what ratio of" recycled" oil was adding back in the tank would bug me.
Be careful with the collection of those fuel vapors for sure.
I’m not knocking the collection of unburned fuel, I really like the idea ! Jim

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[bill-mcnamara]

VinTin,
Thanks so much for the excellent pics and quantitative data. I’m totally amazed at the volumes of fuel mix you are collecting, and I’m certainly going to add recovery systems to my RD’s.
Another request:….do you have a pic of the bleeder valve cover modification.
Bill.

[chris-p]

I cannot seem to find one on my computer. If Vin Tin doesn’t have one, Ill go out and take a new picture.

Pretty easy though, simply plug the hole, and drill/tap in a barb, to attach a fuel line to.

[vintin]

quote pugetsoundboater:

I like the idea of collecting the unburned mixture and reusing it. But after looking at the photo of the collected mixture in the clear container it looks most likely a higher percentage of oil than the original mix. This would throw off your oil:gas ratio considerably after adding it back into your tank,and add to the issue you are trying to solve .
I really try to get my fuel oil ratio close to exactly the recommended ratio ,and a slight bit more,to compensate for Seafoam and fuel stabilizer added to the gas. Not knowing what ratio of" recycled" oil was adding back in the tank would bug me.
Be careful with the collection of those fuel vapors for sure.
I’m not knocking the collection of unburned fuel, I really like the idea ! Jim

It bugs me too not knowing exactly what I’m adding back to the main tank.

Sometimes if I’m adding a lot of recovered fuel I’ll go 32/1 on the mix ration when i top up the 15 gallon main tank.

A friend of mine had a recovery system on a 35hp some years ago and only had a 1 pint tank. Not good. He got tired of it due to it getting full all of the time.

Chris P., I don’t have a good photo of the drain case reed valve cover. If you’ll got one please post it up. I did place the hose barb in the lowest possible spot on the cover figuring that is where the liquid fuel would pool first. This is directly across of the drain hole that leads into the lower unit housing.

[chris-p]

I would think the best thing to do would be to almost run the tank out before filling it. Always keeps fresh gas and a fresh, properly mixed mixture of fuel/oil. That was my thinking when I ran the return line back to the tank. Told him to not always fill up when the tank was only 1/2 or 3/4, as after many tanks, your mixture may go off. Perhaps.

I have not added a vent line to the carb intake on the ones I have done. Good idea though. By the time it runs back down the line, and is remixed in, I don’t feel there is any additional threat, in comparison to a normal, single line tank venting to atmosphere. But as stated, an additional improvement, and good idea.

[vintin]

Just got back from about three hours on Lake Lanier. I topped up the 15 gallon tank adding about 5 gallons mixed at 32/1 before launching. Motor ran good. Some of the fuel in the tank is from last fall and some was added about a week ago. Recovered fuel added to the main tank anytime the one gallon has a half gallon or so. Usually on fill up. I very rarely run the 15 gallon tank to below about 3 gallons.

Something else to consider about using recaptured fuel. The composition of the recovered fuel changes. From what I’ve read condensed fuel is called ‘tailings’. Tailings are the heavier and less easily vaporized components of the fuel. I’m sure the oil component of the fuel/oil mix condenses out more easily, too.

So in the end I’m not real sure what the recovered fuel is composed of. It sure does look a darker blue than fresh gas/oil mix. The motor runs good and I feel good about it.

[jim-moffatt]

After I installed the bleeder recovery system going to a tank in the boat I rerouted it to a nipple I installed just behind the carb on the intake manifold. So recycling was automatic. It worked well with the following caviat. Just like a motor with no bleeder, during acceleration from slow speed, it takes several seconds for the unburned fuel to clear so it runs very rich and burbbly during that time. When pulling up a skier it is not what is wanted.
During deceleration it goes lean for several seconds and pops a lot. But thats not a real problem. Right now I still send the fuel to a tank in the boat.I enjoy the smooth acceleration to full power from a long period of trolling.

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