Outboard Fuel

[John T1594]

I have a ten year old Nissan 5 hp 2-cycle that I use for my dinghy. It has been a great engine except for the past few years when they introduced 10% ethanol into the gasoline. Every year I have to take the engine to my local mechanic to have the carb taken apart, cleaned and/or have the jets and other parts replaced. Even when run only briefly and with new gas, the bowl has water and grit in it and the engine either won't start or runs badly. I have taken to running the carb dry at the end of every weekend and have a a fuel filter on the line from the tank. It seems that no matter what I do, the engine goes to the shop at the start of every season.

I recently found out that 100LL Avgas, the type used for private aiplanes is ethanol free and is listed as "low lead" (LL). I am tempted to try this gas this season but wonder what effect the lead will have on the engine. My owner's manual specifies unleaded gas. I'm not so worried about the spark plugs fouling but want to avoid any more serious problems or damage from the lead.

 

[tommays]

I have run the 2004 4 HP Mercury(same motor more or less)without issue on E-10 and have only drained the bowl at season end

I use the 3 gallon remote tank and do not use and extra filter so i would suppect your fuel supply is less than good

 

[Ross]

I suspect that the problem is your remote fuel tank. When was the last time you completely emptied it and dried it in the hot sunlight with the caps off? I have run a 2 cycle lawn mower for more than 15 years buying gasoline for it when I buy for my car. mower and fuel are stored under cover when not in use. I never have any trouble with it.

 

[Don S/V ILLusion]

John I have the same outboard and had the same issues you described until I started using Av-gas which cured the carb and water problems.
Not sure the lawnmower metaphor is a good one since those things will run on anything including my used motor oil.

 

[Ross]

I wonder with all of the chainsaws, weed whackers, leaf blowers and outboard motors in use why some people have continuing problems and others just put gas in them and pull the cord and go, day after day, week after week and year after year? I can't believe that it is defective equipment.

 

[sailingdog]

Lead probably won't affect it much. The main reason leaded gasoline was phased out was that lead, which was used as an octane booster IIRC, destroys the platinum catalyst bed in the catalytic converter. Since your engine does not have a catalytic converter, it should not be much of an issue.

Do you buy your fuel from a marine fuel dock or a terrestrial gas station? Do you filter the fuel with a baja filter? Do you have an on-board fixed fuel tank or a portable one?

Using a terrestrial gas station makes more sense, since they usually have better turn over of fuel and are less likely to have water in their tanks. Filtering with a baja filter would help separate any debris or water from the fuel. Adding a racor-type fuel/water separator filter to the engine fuel line is also a great idea, even for a small outboard. BTW, my boat is outboard powered and I've had ZERO fuel issues, but I added a Racor 025 fuel/water separator filter to it when I got it.

This is the one I have aboard my boat:

If you have a fixed fuel tank aboard, when was the last time you cleaned it out and emptied it completely.

I have a ten year old Nissan 5 hp 2-cycle that I use for my dinghy. It has been a great engine except for the past few years when they introduced 10% ethanol into the gasoline. Every year I have to take the engine to my local mechanic to have the carb taken apart, cleaned and/or have the jets and other parts replaced. Even when run only briefly and with new gas, the bowl has water and grit in it and the engine either won't start or runs badly. I have taken to running the carb dry at the end of every weekend and have a a fuel filter on the line from the tank. It seems that no matter what I do, the engine goes to the shop at the start of every season.

I recently found out that 100LL Avgas, the type used for private aiplanes is ethanol free and is listed as "low lead" (LL). I am tempted to try this gas this season but wonder what effect the lead will have on the engine. My owner's manual specifies unleaded gas. I'm not so worried about the spark plugs fouling but want to avoid any more serious problems or damage from the lead.

 

[Ross]

If you have a removable tank how do you protect the hose ends and the connections to the tank and engine? How do you store the fuel tank and hoses? Some marinas have their fuel tanks located where very high tides can flood them. All of the gasoline powered farm and industrial equipment I have ever seen had a glass sediment bowl in the fuel line.

 

[Joe Snuffy]

Marine Sta-bil.
Linky from West, but you can get it anywhere. Good Stuff.
http://www.westmarine.com/1/1/30251-marine-formula-sta-bil-8oz-from-sta-bil.html

 

[sinnettc]

I've made a point of keeping E-10 out of my 2008 Merc 4 cycle. Ethanol free gas is available for boats and agricultural purposes here in Oregon.

We bought Verboten 1/2 way through the summer so that first year I bought ethanol free premium gas from the county-owned marina across the lake from ours. It cost me about $18 ($6/gal) to fil my 3 gallon external tank . At least a gallon went into the truck at the end of the season.

Last year I launched before they were open, so I went to the local Cenex farm supply and bought a 5 gallon drum of ethanol free premium. IIRC it cost me $45! I nearly choked but paid the price as I had a schedule to keep and didn't have time to shop around. 1.5-2 gallons went into the truck and maybe 1/2 gallon into the mower.

This year I'm planning to do the avgas thing; one of the local airports is apparently set up for self-serve (unusual in Oregon) and a lot of local boaters go there for their boat gas.

 

[John T1594]

Thanks for all the replies and advice.
FYI - I empty my external tank at the end of each season, then rinse the tank with solvent and let it dry in the sun with the cap off. I also drain the fuel hose and squeeze pump as best I can. I also recently replaced the entire fuel line and squeeze pump from my external tank. I buy all my gas a a local and very busy "terrestrial" station and use Stabil in the fuel during the season. I don't filter the fuel when I buy the gas but I have added a primary filter on the fuel line from the tank and there is a second filter inside the engine cowl. I put in a new plug at the start of the season.
My mechanic has suggested that I consider a new or rebuilt carb but I have already replaced most of the parts of the carb with rebuild kits. Switching to Avgas seems like a reasonable and cheaper experiment. I was just worried about using a (low) leaded fuel in this engine.

 

[zeehag]

i always used an inline filter on my outboards--worked like a charm--at first i was having to rebuild carb every 2 weeks--lol--got reallly tired of that reaallly fast--slapped inline filter--ta-daaa--i was in heaven--didnt ever have to rebuild carb again..LOL.....also look at your remote tank--is always a problem--condensation anjhd sometimes seawater--if ye are in appropriate locale for such--get into it and foul the works--close vent between uses..lol...worked great--gooodluck

 

[Rick Webb]

We Have 4 Outboards in our Junior Sailing Program

The other board of director members selected me to be in charge of maintenance for them by default, I was willing to play with the damn things and they were not. We have learned a few things.

First we have found buying gas from the gas station is false economy; get it at the marina for the amount you use you’re not saving much. If we burn 100 gallons in the course of our lessons and pay 30 cents more a gallon that is a whopping total of 30 dollars

Second we added big filters inline list at $60 or so at WM filters are $14. Shop around our Port Supply account makes for a big savings on these. If you’re in salt water don't mess with the aluminum one (usually painted black) get the stainless steel one.

Third we gave up on rebuilding the carb just replace them they are not that expensive. Maybe a better shade tree mechanic can fix it but by the time you pay him it comes out the same.

Lastly use the motor ours were getting used all day most of the summer than not much till the next summer. The last couple of years we have run the boats each month then unhook the fuel line and run it dry to get all of the fuel out of the carb. Just running the motor with the muffs on does not get fuel through all the carb passages you actually need to put it in the water and put some resistance on the prop. Not sure about running the new ones with fuel injectors should probably check with the tech at the dealer on that one.

Also don't volunteer I should have known that one already

Using AVGAS won't be a problem the lead is no issue but the higher head temps might create problems under high load but I don't think our small outboards will be hampered by that issue.

 

[Ross]

Re: We Have 4 Outboards in our Junior Sailing Program

A funny thing happened on the way to the forum. I have asked my grand daughter to mow the lawn for me until I am able again. So I figured I had better make certain that she had a mower the would work . So I hobbled out to the shed and pulled the mower out, checked the gas, there is about half a tank, pulled the cover off the air cleaner, the foam is still there, so I sprayed a shot of starting fluid on it, turned on the gas, primed the carb, and pulled the starter cord. The engine started and ran normally for several minutes until I shut it off and pushed it back into the shed.

 

[Rick Webb]

Ross

We should just put lawnmower carbs on the outboards.

Just this morning I tried to buy a new one for my old lawnmower the guy said you won't need one and it is probably back ordered anyway sold me five dollars worth of gaskets and stuff, put the seat in for the needle valve for me because he said everyone messes that up put it back together and it started on the first pull now it runs like a champ again.

On these new outboard carbs the tolerances are so tight that the smallest bit of gunk screws them up the passages on the lawnmower were huge in comparison.

 

[sailingdog]

My point about buying gasoline from a terrestrial gas station rather than a marine fuel dock is that many marine fuel docks just don't have the fuel turn over to keep the fuel really fresh. That generally isn't an issue for a busier terrestrial gas station. Also, most boats small enough to be outboard powered, don't have permanent fuel tanks, so carrying the tank to re-fuel it at a gas station generally isn't an issue.

 

[Rick Webb]

The Issue is Eathanol

The gas at the marina is not going to have any eathanol just as the AVGAS does not have any.

 

[captainpat]

As Rick asserts, "the issue is ethanol". You can clean you fuel system every week and it won't cure the difficulty with ethanol. I have a small 3.3 Merc. with an internal fuel tank. Same problem(s). Talked to a Merc repair shop. Found that ethanol does not effect plastic tanks (as opposed to fiberglass) but the fuel, when stored for several weeks, "phases" thereby attracting water and causing fouling and rusting in some of the fuel system parts. Solution? Add a carb cleaner and a stabilizer to each tank. It helps if you can buy fuel in smaller quantities so that it doesn't sit for long periods.

 

[sailingdog]

A lot of marine fuel docks have ethanol blend gasolines at them... You need to look pretty far in some areas to find ethanol free gasoline.

The gas at the marina is not going to have any eathanol just as the AVGAS does not have any.

 

[Rick Webb]

Ethanol Free Gas

None ZERO of the marinas around here have ethanol in their gas stay away from those that do if they are around you and there are still a few places on the road here without it. The Feds are bribing the distributors into putting it in. Maybe a regime change can reverse it but the Energy Department is still talking about increasing the amount of ethanol in road gas not less despite all the evidence that it makes little sense.

 

[Ross]

Maybe gasoline should have a "best if used by" date on the pumps, just like fresh milk.