Fishing with Rod Discussion Forum
Fishing in British Columbia => General Discussion => Topic started by: Spawn Sack on August 14, 2015, 12:15:55 PM
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Somewhat lame topic...but what the hell :o
New (to me) motor is 2011 Merc 90/65 jet. 2 stroke. Never thought to ask original owner what grade of gas he used.
Manual say min 87. I'm inclined to just run 87. However talking to boat guys at work several say the use/reccomend 91 or 94.
My dad who has a 175 merc sportjet in his jet boat only runs 94. Says his motor starts and runs better on it.
Is it all in their head???
IMO motors that say min 87 typiclaly run FINE on 87. For example my chainsaw, quad, 4 stroke 5hp outboard and so on all run fine on 87. That being said I have never tried higher octane fuel in any of them. Perhaps they would run better and I don't know cuz I never tried? ???
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The bigger thing is to make sure you use gas that is ethonol free. Higher octane usually contains less ethonol, that is why the motors seem to run better.
Its not the octane necessarily. Google ethonol and outboards....its scary.
Ethanol is hygroscopic, meaning it has a strong attraction to moisture. Ethanol increases the amount of water accumulating in fuel tanks. Ethanol produces less energy (BTUs) than an equivalent unit of gasoline. Ethanol fuel’s usable life span may be less than the normal length of off-season boat storage.
One of the biggest reasons why ethanol fuel and boats don’t go together is that ethanol has the unhappy ability to attract water. And as almost everyone knows, water in gas engines is a serious problem.
Be sure to have a high-quality (25-micron minimum) marine fuel-water separator (filter) installed in the gas line, and check it and replace it often. This filter prevents not only water from getting to the engine, but also debris that may result from ethanol degrading a boat fuel tank and gas lines.
And here is a handy list, I just go to Costco for my boat gas;
http://pure-gas.org/index.jsp?stateprov=BC
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For the last few years the jets in my carb on my 1999 15hp Merc 4 stroke kept getting clogged after barely using it. I kept having to take apart the carb and clean it thoroughly every year until last year when I called Mercury and asked them why my carb kept clogging up and they said it was the ethanol in the gasoline, and they suggested that I switch from 87 octane to ethanol free gas - most Shell stations their 91 octane is ethanol free. Even though its recommended to use 87 octane on my motor, the Merc guys said to use higher octane that is ethanol free and to make sure to use the Mercury fuel treatment stuff every time I fill up the tank. Ever since I switched to higher octane ethanol free gasoline my carb has ran perfectly. Its crazy the damage that ethanol does to carbs! (its even crazier that we're using corn (food) to make gas)
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The bigger thing is to make sure you use gas that is ethonol free.
Exactly.
In a marine motor, ethanol free is more important than high octane. I doubt that you could feel a difference in your boat between running 87octane and higher.
The catch is, ethanol free gasoline is usually only offered in some brands highest octane so you need to buy high octane to get what you need.
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Interesting! Thanks guys for the info.
I could be wrong, but I thought all Costco gas says "may contain up to 10% ethanol," including their 91. I know for sure the Chevron 94 says "contains no ethanol."
If I'm going to Abby (live in Chilliwack) I will try and bring a couple of 20L jerry cans for the boat and hit up Costco (assuming their 91 is e/free).
Now this is probably a dumb question...but why is ethanol so important in marine motors? Yes I realize the motor always runs in water, but I didn't think the water cooling the motor and falling from the sky would get into the fuel. Does it? How?
I use my chain saw and quad in wet/moist environments and just run 87 in both of them. But I guess the quad is 4 stroke EFI. Would ya'll run ethanol free gas in you chainsaw too?
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Ethanol is important to keep out of your fuel, because ethanol is hygroscopic. Little more detail (sort of) than stated above is the humidity in the air is enough to saturate the ethanol to it's max level fairly quickly, which means the moisture it draws in can no longer be absorbed, which leads to fuel separating into the gas. Now, this isn't an issue if you use a lot of fuel and use it often, but when sitting it can be problematic.
This also rings true with your vehicles brake fluid and coolant, as both of those fluids are hygroscopic and will absorb it's max amount of moisture (roughly 4%) in about 2 years on the coast. Any excess moisture will pool in your master cylinder, and worse yet in your ABS pump or calipers. As for coolant the boiling point will go down and can cause issues (though not really seen in warmer temps)
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And here is a handy list, I just go to Costco for my boat gas;
http://pure-gas.org/index.jsp?stateprov=BC
Interesting, I didnt know any automotive gas was available nowadays ethanol free. I recently picked up a used aluminum that came with a 90's era's Yamaha 2-stroke. The previous owner said he just used regular 87 octane and the motor was a little tough to start up after sitting since last season. He had been using 50:1, presumably with no stabilizer, while the sticker on the motor said 100:1 so I just chalked it up to the old gas but now I wonder if the ethanol content could have been a factor too...
I haven't had a chance to take it out yet, but will definitely chuck out the old gas and mix up some new ethanol free fuel with the lowest octane rating I can find, which based on the above link looks like will be 91.
On a related note, any suggestions on how to dispose of 10 litres of year-old 50:1 mix?
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Its brutal. Only a few years ago I only had to watch out for ethanol at budget gas stations and Husky I think, but now I think its even in Chevron unless its 94...
Well at least it says it "may contain"
Corn is in everything nowadays! Horrible!
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I had a thought after I posted last night. An argument where one would want ethanol in their fuel, especially if moisture is an issue.
With our humidity, moisture will be in the fuel no matter what. Now if you had fuel with ethanol, this would be no problem as it would absorb it, and get burnt off harmlessly, but without ethanol, it does not get absorbed and can create a later on the fuel, which can be put through the engine in a more harmful way. I would say ones bestb bet is a good water fuel seperate and check often.
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Most Shell gas stations have 91 octane that is ethanol free. Might save you trips to a bunch of different gas stations - just go to a Shell and see for yourself
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Although there are some exceptions at other stations, from what I have seen Shell 91 and Chevron 94 are both ethanol free.
Most stations and grades will say may contain ethanol and generally if it says may they mean it does.
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Engines are designed to run at the Octane level indicated by the manufacturer. My understanding is the science does not support running higher Octane in these engines. However ethanol does use more fuel to produce the same power. 3 to 4% by US government estimates. Older engines may benefit as there is concern ethanol may be corrosive for some components. Newer engines should be designed to deal with it.
Most peoples vehicles see more moisture than many boats or outboard motors ever do. My outboard is stored in my garage most of the time.
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All good input, thanks guys. I am thinking of implementing the following:
For now, just run ethanol free gas in the boat. Costco or Shell 91, or Chevron 94.
When I have some extra cash, buy a fuel/water seperator/filter and install in main gas line. We are more or less tapped out cash wise on the boat after purchase price, and the TAX. Plus we need to get a proper anchor/bow roller for the Fraser, plus we have a fish finder that may or may not be usable depending how my next round of trouble shooting goes :o
Any know about how much these fuel/water seperators go for? Merc has one that looks decent:
https://www.mercurymarine.com/en/ca/parts-and-accessories/mercury-marine-products/fuel-care/fuel-care/
I like the looks of this one better as you can drain the water out without having to remove/unscrew the filter.
http://www.westmarine.com/buy/racor--replacement-gas-filter-water-separators-for-mercury-mercruiser-engines--P000411462
Just another thought....
Do you think one would be okay to ONLY run ethanol free gas and not bother with the fuel/water seperator/filter? In other words, does/can ethanol free gas have issues with moisture? There is a fuel filter in the fuel line near the motor. Would it be overkill to run the extra filter and the ethanol free gas?
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I feel we can be getting into superstition area now, and personal preference. I'm an overkill guy, and enjoy the ease of unscrewing a t-bar to drain the water like on some diesels. The fuel filter itself will just be for particles, and the filter material itself won't be fine enough to trap water.
I reckon 87 Octane (or manufacturer's recommended), water separator, and new fuel when you know it'll be sitting for extended periods and you'll be gravy.
Side note: I am not an outboard guy, and am just applying my automotive schooling here.
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--funny when we had regular fuel...everyone reccomending adding ethonol... to stop freeze up and reduce condensation .
--I use higher octane in modern 90 4 stroke and always put stabil type product in it as I only go through a few tanks of gas a year. Old boat 85 used to burn 45 gallons in a weekend.
--All Voodooo to me.. I use petrocan because it is the closest station. Cheveron and Shell are in town and the highest prices in the land.
--I think sometimes you just get a cranky engine that only seems to want to run on a particular brand.
--My engine is a 2006 have had no problems.
--Older engines I can see a problem... I was so happy when I got my new engine fuel injected.
--
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I feel we can be getting into superstition area now, and personal preference. I'm an overkill guy, and enjoy the ease of unscrewing a t-bar to drain the water like on some diesels. The fuel filter itself will just be for particles, and the filter material itself won't be fine enough to trap water.
I reckon 87 Octane (or manufacturer's recommended), water separator, and new fuel when you know it'll be sitting for extended periods and you'll be gravy.
Side note: I am not an outboard guy, and am just applying my automotive schooling here.
I would be inclined to agree with you. For now I think I'll just run ethanol free gas and after we get some higher priority stuf sorted out on the boat, down the road I'll look at the fuel/water seperator filter. Only thing I don't really like about them is they need to be installed on the main fuel line somewhere, and most likely in a vertical position to work properly. Would want it somewhere where it couldn't easily take an impact (someone slips or whatever) and busted open/apart. Would have to take some time and think where it could go to be as out of the way as possible. Ideally under the floor but I doubt one would fit there.
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I would be inclined to agree with you. For now I think I'll just run ethanol free gas and after we get some higher priority stuf sorted out on the boat, down the road I'll look at the fuel/water seperator filter. Only thing I don't really like about them is they need to be installed on the main fuel line somewhere, and most likely in a vertical position to work properly. Would want it somewhere where it couldn't easily take an impact (someone slips or whatever) and busted open/apart. Would have to take some time and think where it could go to be as out of the way as possible. Ideally under the floor but I doubt one would fit there.
--I have a removeable box around my filter and of course an in line shut off valve as I run line to both main and kicker through the filter. Agree a lot of connections where things can go wrong even if checked and maintained.
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At least in the LML, it appears marinas all seem to have mid-grade 89 ethanol free fuel. I assume there's no issues with those marina fuel docks, like stale gas etc?
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I'm not entirely sure as I've never fueled up at a marina. I'll be primarily hitting up the fraser adn connecting rivers and a bit of lake trolling so for me it'll be Chevron, Shell, etc.
Plan is still to burn ethanol free gas whenever possible, and down the road the road if the logistics/location looks good for a fuel/water seperator filter to install one of those then probably step it down to 87.
Thanks for all the input guys appreciate it.
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I bought a slightly used 4 stroke 75 merc 2years ago at a marine shop they told me all it needs is regular, but I must agree with the ethanol issue, it traps water
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i would stick to the costco 91. at the Langley costco you can usually get 91 for a couple cents more than regular at other gas stations. maybe the abbotsford costco is even cheaper because the transit tax dosent apply. i put it in 50hp jet and in one of my mustangs.
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Another issue with ethanol is its tendency to degrade some non metal bits on older engines. Newer ones are built to take it but this can be another source of problems for the older two strokes.
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Another issue with ethanol is its tendency to degrade some non metal bits on older engines. Newer ones are built to take it but this can be another source of problems for the older two strokes.
Bingo…….on top of the H2O absorption and phasing issues with Ethanol it will destroy older rubber seals and lines, newer motors have neoprene rubber seals and lines to combat the alcohol.
Its evil stuff in an older engines especially in marine applications, lots of documented evidence of this, just read your mfg recommendations.
Just because some have been lucky saying its ok is the same as saying the old polly-B plumbing was ok.
As for the original post about octane……
Running higher octane than recommended will increase the temperature in the cyl head and pistons……….period.
Too much octane will be a problem in any motor however, how much is too much is dependant on engine and load.
Personally I would run ( and do on my own engines that burn gas) the 94 non ethanol and monitor plugs to ensure temps are in check.
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As for the original post about octane……
Running higher octane than recommended will increase the temperature in the cyl head and pistons……….period.
Too much octane will be a problem in any motor however, how much is too much is dependant on engine and load.
Personally I would run ( and do on my own engines that burn gas) the 94 non ethanol and monitor plugs to ensure temps are in check.
that's a myth
low octane can cause higher combustion temps. do to pre ignition and detonation. If you don't have those problems the only thing high octane will do is drain your wallet.
Montoring your plugs is checking for air/fuel mixture and maybe some oil. Too much air runs hot, too much fuel runs cold. Your plugs won't tell you your octane is too high or low.
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Interesting comments by Sr SQ and Canso. The manual says "minimum 87" but does not say anything about "do not exceed XX octane." I am by no means a mechanic but for what I have heard over the years burning gas higher in ocatne than needed will not harm the motor but if not needed is just wasting $. For example our 4Runner runs fine on 87 and is made to run 87. So we use 87. My car has a tightly wound DOHC motor and calls for min 91. I always run 91 as the motor sounds a bit growly and underpowered on regualr gas.
Any opiniuons on "best" fuel/water filter?
Looks like the Mercury one you can not drain just the water out. You need to replace the whole filter like an oil filter. I have seen other brands online (Raycor?) where you can drain just the water if you want from a clear bowl at the bottom of the filter. Seems like being able to SEE if any water is being drained from the fuel and being able to remove it is a good feature.
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I went cheap and used regular 87 in my Honda 4-strk for the entire season last year and winterized my boat with some fuel stabilizer in the winter. It was a BAD decision :-[
Motor gave my all sorts of grief this spring to the point that I had to call Honda for help. Service manager told me 'never put gas with ethanol in a built-in fuel tank. In a portable tank, always drain gas at the end of season b/c ethanol+plastic = trouble. Always use Shell 91 or Chevron 94 and add some Seafoam to it'. That recipe saved me a lot of $$$ because it removed the trapped water from the carb and also burnt the gunk and cra* from the fuel line. After a few trips, motor is now back to its normal and isn't acting up anymore.
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Guys,
I work with fuel, a lot. I work with the CSA on producing fuel handling specifications, and I regularly deal with CAN/CGSB standards on fuels. If you don't know what those are, please look them up.
This thread has a number of partial truths and some complete falsities. Let me try and clear the air as quickly as I can.
- Ethanol adds octane to gasoline.
- Ethanol is a hydrophilic, meaning it likes water.
- Gasoline is hydrophobic meaning is does not like water.
- Gasoline can be blended with ethanol to achieve the advertised octane rating (remember this!) but also makes it able to absorb more water.
Gasoline is produced to a specific standard and it is very, very dry. Dry fuels, amongst other things, have a tendency to absorb moisture from the atmosphere. Gas tanks "breathe" with changes in temperature and the fuel volumes expand and contract with the heating and cooling cycle. This process brings in fresh, moist air.
Unblended gasoline can already hold dissolved water, but when blended with ethanol the ability to hold water is increased. At a certain level of saturation, ethanol blended fuels can hold no more water, and the ethanol/water mixture will literally drop out of suspension (phase separation) to the bottom of the tank. This leaves you with a corrosive cocktail at the bottom of your tank and decreased octane gasoline floating above it. This is bad. The fuel pickups are also on the bottom of your tanks meaning that this mixture will undoubtedly be ingested by your engines.
So, in summary. Ethanol blended fuels are FINE as long as you are not storing them for ANY LENGTH OF TIME! Storing ethanol blended fuel in a moisture rich environment is inviting problems. That said, some heavy users believe the use of ethanol blended fuels is actually a good thing in boats that are regularly used as it can hold more dissolved water resulting in less free water at the bottom of their fuel tanks. For most of us weekend warriors ethanol blended fuels are going to sit, tank vents open, absorbing moisture from the air, creating problems.
If you're a weekend warrior like me, pay a bit more at the pump and avoid ethanol blended fuels. An ounce of prevention is worth a pound of cure, right?
Points for consideration:
Q. Fuel stabilizer will prevent the absorption of water into fuel
A. No. Fuel stabilizers are used to prevent the chemical decomposition of gasoline into an unusable state. It cannot change the actual properties of the fuel.
Q: Higher octane fuels burn hotter
A: No, they do not. In fact higher octane fuels burn slower when combusted. Octane is a measurement of a fuels resistance to detonation or knock, not its MJ/kg (in short terms, energy). This is important in higher compression engines like the example above.
Q: Fuel filters will remove all water from fuel
A: Most water can be caught by an inline fuel filter in addition to particulates. I recommend the Racor line of inline spin on fuel filters from Parker. The ones with the reusable clear bowls allow you to see if there is water being picked up from your tank. Most retail fuel dispenser have 10 micron filters in them, so the use of 10 micron is what I would personally use.
I hope this helps clear the air about octane and ethanol blended fuel.
Cheers,
Shaun
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Great post. I always use premium fuel ( highest octane ) in my out boards and a fuel stabilizer when storing fuel over the winter months.
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Excellent post, Shaun. Thank you.
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Awesome Shaun! Can't thank you enough for that info.
When I have a chance I will buy and install a fuel/water seperator filter (probably the Racor). In the mean time, I will use ethanol free fuel as I don't run the boat more than once a week or so, and over the winter it will sit for several months in the tank.