can someone please explain this (non-motorcycle)

[Kretz]

I have a Sear's 21" walk behind lawnmower, must be about 15 years old.

It gets some maintenance, oil changes, air filter etc. but it is not babied, it's always run well (even with a choked air filter) usually I cut the grass & it's put away till next time.

I have for some time (on the advice of a local yard machinery mechanic) been running that lawnmower & my Sear's Lawn Tractor PLUS both my bikes on Ethanol free 91 octane fuel (as many of us do). I was told that the yard machinery mechanic is always repairing machinery due to ethanol in fuel problems.

Recently my lawnmower began acting up, it would start, run for 5 seconds & then cut out. Try to pull start again & it wouldn't BUT if I primed it again it would start run for 5 sec & cut out.

I was telling a M/C mechanic friend about this & his first question was "how old is the fuel?" I said "pretty new & I always use 91 oct Ethanol free gas"

He said "that's your problem" those engines are designed to run on regular gas, & they won't run on "premium" fuel.

To be honest I thought "yeah! right!"

BUT today I went & got some 87 oct regular fuel, emptied the lawnmower tank, replaced the fuel & started the lawnmower.... It ran for a while but cut out. I started it again & it ran but seemed to be "hunting". BUT the longer it ran the better it ran.

End of story.... after a few minutes it began to run fine & continued to do so, just as it always did.

So can someone please throw some light on this? & should we also be using REGULAR fuel in our bikes too, as opposed to higher octane &/ or Ethanol free gas?

[Freebird]

Our bikes do not need high octane gas. I never run anything but 87 in mine. Ethanol free would be great but I just can't get it around here.

[Kretz]

Our bikes do not need high octane gas. I never run anything but 87 in mine. Ethanol free would be great but I just can't get it around here.

The only ethanol free we can get here afaik is higher octane than 87 regular. (ie 91 or Chevron 93)

[camos]

Absolutely regular all the way. Our bikes are ancient and were designed to run on zero ethanol regular and the carbs will gob up on an ethanol blend even if run every day. Seafoam comes to the rescue here, and the other gas modifiers as well. If riding often, that would be every day, giving the bike a dose once a month works for me on a regular ethanol blend. Some guys like dosing every other tank so perhaps it matters if not riding much. If you don't ride through the winter put in about 1/4 bottle and run until the carbs are filled then to pup the tank.

 

I have a 1982 generic mower with a Briggs engine that has been abused since I got it. Never change the oil or plug or sharpen the blade. It requires a little oil once a year. Started using ethanol whenever some git decided that's what we get. Never put Seafoam in it either but starts every time. In 83 I got rid of all the grass on my property but still have to mow the boulevard in front. Don't need to mow from June to October and from November to March. So, it doesn't get used a huge amount.

 

Hard to beat old technology.

[Kretz]

Yes but I was running my lawnmower on Non-ethanol fuel, so surely it should have run ok?

I was amazed when it started & ran on the ethanol fuel but wouldn't on the non-ethanol.

I wish they'd stop pi$$ing around with fuel, I remember years ago when they did away with lead additives in fuel, I had an old Fiat X1/9 & then I had to find a lead additive/ substitute to add to my fuel.

[Freebird]

Well, I'm surprised that switching from 91 to ethanol 87 corrected the problem. I'm just saying that 91 is way overkill for that motor. Would it hurt anything? I wouldn't really think so. I would love to winter store my engines with non-ethanol but the only place to buy it here is the pumps at the marinas and that is usually a long way to lug a can or cans of gas.

[Kretz]

Well, I'm surprised that switching from 91 to ethanol 87 corrected the problem. I'm just saying that 91 is way overkill for that motor. Would it hurt anything? I wouldn't really think so. I would love to winter store my engines with non-ethanol but the only place to buy it here is the pumps at the marinas and that is usually a long way to lug a can or cans of gas.

 

I was surprised too (absolutely amazed actually!) the only reason I use the 91 in garden machinery is it's the lowest octane gas around here without ethanol. Yard tractor also sits for extended periods especially in the winter!

I accept that 91 oct is overkill for a small B&S lawnmower engine but I was trying to run it without ethanol. I like you thought where's the harm? But maybe I was doing more harm than good by trying to run without ethanol. Seems crazy to me!

[zagger]

Maybe the higher priced, non-ethanol stuff, is old stale gas because nobody actually buys it! I sure don't. Only the cheapest junk goes in my gas powered stuff!

zag

[BlueSky]

I use ethanol free 93 octane gasoline in all my yard tools and motorcycles because it is available locally and I've found from experience that the carbs don't clog up as bad when sitting a long time. Ethanol will emulsify water if any is in the gas. Otherwise the water will settle to the bottom of the tank and cause running problems.

[cowpuc]

Might just be you picked up some water or something in the old gas and refreshing it alone did the job,, I too highly doubt the "fix" had much to do with Octane level or the blend. Like some others on here - I stay away from high octane levels and just run the cheaper 87.. Funny thing, when traveling out west like we currently are I find a LOT of 85 Octane - always have.. I have ran that stuff alot while CTFW and never been dissatified with it - nary a ping one and I am usually loaded up pretty good and a passenger in the rear saddle..

Storage methods vary like oil preferences IMHO.. Personally, if I am gonna store for more then a month I either fuel em up full and start em at least one a month and run em till they are up to operating temps (ALWAYS loved doing this with my snowmobiles too - nothing like the sweet sound of a Thundercat or a Mach Z during the heat of summer) or I do the full stage storage maintenance including fogging the motor and draining the carbs.. Fact is,, what Kretz is describing is a classic from the world of which I came. I had wayyy more customers with machines that hadnt been started for a few months come to me, able to start em on the choke circuitry but unable to get to stay running than I care to think about. Carb cleaning was a normal course of doing business back in the day.. The smaller engines were always the worst because their orfices/jets are smaller and plug easier..

Frankly Kretz,, I say ya done got lucky,,,, take it back,, maybe not cause now ya gotta go cut your grass

[snyper316]

I have to wonder about this and will watch the mileage now on the bike because yesterday I put in the cheap 1.87 gas in Tinker because well now I have to take 50 mile trips 2wice a day I figured gas wont sit long enuff, the last time I put 87 octane in I got 40 miles to gallon so I will see, I have been keeping my RPMs at 3500-4200 just well because I can and just have to watch speedo more carefully because my wrist has a twitching problem...

[saddlebum]

Whether or not you should be using regular or high octane fuel is based mostly on the compression and timing specs of your engine. The higher the octane is, the slower it burns it actually (contrary to popular belief) is not necessarily a better grade of fuel. In a low compression engine you can actually loose performance and get worse fuel millage burning 91 octane or higher because it does not ignite as readily. In high compression engines higher octane fuel is used because it has a higher flash point, this is to prevent what is commonly referred to as pre-ignition. Many older folks may recall the unexplained rattling noise coming from your engine when pulling a loaded trailer or climbing a steep grade. You either retarded your timing (which resulted in power loss or you ran a higher octane fuel. In simple terms Octane is a flame retardent it raises the temp required for fuel to burn or ignite. Todays engines with all the electronics and sensors are able to control preignition where older non-electronic engines could not so a good part of the sales rhetoric to put higher octane fuel in your vehicle is plain hype. However some smaller engines like weed eaters and chain saws require the higher octane fuel, Why? Because those little guys run very high compresion ratios and regular gas can damage the pistons due to preignition. If you ever see a piston that has suffered preignition damage it will look like some one had a field day with a little shot gun.

Edited July 15, 2017 by saddlebum

[Kretz]

Thanks for the input guys, much appreciated, but just to clarify guys, none of the gas I was using was old or dirty. A few weeks old at most I get it at Costco, & they have a pretty high throughput of gasoline in all grades. (so it hasn't sat in their tanks forever) I use their 91 simply 'cause I was told it had no ethanol.

I just can't understand why my lawnmower would not run on 91 ethanol free but runs great on 87 with ethanol. It's just weird.

Then that set me off worrying about what I put in my bikes.

& Puc you're correct I did have to cut the grass! LOL

Saddlebum thanks for your explanation, it kinda makes sense, but then again we have guys running 93 non ethanol & 87 with ethanol? I'm just totally confused now.

Edited July 15, 2017 by Kretz

[camos]

I just can't understand why my lawnmower would not run on 91 ethanol free but runs great on 87 with ethanol. It's just weird.

Then that set me off worrying about what I put in my bikes..

It is kinda puzzling isn't it.` I live on an island and there is some extra humidity which might make ethanol gas more prone to collecting water. Perhaps the people who have difficulty with ethanol live in an area of even higher humidity. I ride my bike every day and it will get a little ****ty in two or three weeks but my lawn mower can sit for six months and still start on the second pull.

 

You live just across the pond from me so just use regular 87 like I do and don`t worry about it damaging your bike`s engine cuz it won`t.

[saddlebum]

I found some times using different grades of gasoline when you don't need to is kind of like giving a patient a placebo. I bought a truck from a good friend of mine who always told me he got more millage and better power when he ran premium gas yet when I tried to compare with the same truck after i bought it just for kicks the only difference I found was I paid more per gallon for gas but gained nothing. Maybe he just had more faith than me.

[frankd]

I agree with CowPuc.....It sounds to me that you picked up some water in the non-ethanol gas. Ethanol gas will absorb some water, so it probably finished getting the water out of your carb and that's why it ran better and better as you ran it.

[BlueSky]

Last year on my trip to Wyoming, I was curious about the low octane gas that was available. I'm told that at the higher elevations, 85 octane is all an engine needs that would require 87 at sea level since the air is thinner. I still bought 87 octane for my truck not knowing that 85 was okay. And, I was able to notice a huge difference in the horsepower of my truck at the higher elevations. I wasn't checking fuel economy on the trip but it wasn't good.

[Flyinfool]

+1 more on what Cowpuc and Frank said.

 

I did some actual testing with 91 ethanol free and regular 87 with ethanol.

In small engines with no computers to take advantage of the higher octane, they all actually made less power on the 91. This is because the higher octane actually burns slower and cooler, with the high RPMs that these small engines run the exhaust ports were open before the fuel was done burning. So the engine temp was cooler but the muffler temp was was about 200°F hotter. Running against a fixed load the peak RPM was also about 200 RPM less, so there is noticeably less power available. This is true in lawnmower size and smaller, like weed eaters and chainsaws.

 

In my Venture I was unable to measure or notice any difference in performance or mileage other than the weight of my wallet.

 

BUT in my P/U truck Chevy half ton with all the computer stuff, I ran a test where I used premium for a full year, writing all the info down in a log book. Based on a full year of premium vs a full year of regular the premium does get better gas mileage, which makes since since the computer can advance the timing to take advantage of it. Because the computer can take advantage of it, my 0-60 time was also a bit better with the premium. BUT and you know there always is one, when I did the $ per mile calculation. Regular still won by a bunch. the $/mile was a lot closer on the occasions where I could get ethanol free premium (the nearest ethanol free is 98 miles away), but the 87 still always won.

As a result of the test I do use the high octane when I hook up the RV to hit the road, That little extra HP is noticeable to get that 6200 lbs going, and the slightly better gas mileage is simply more convenient, I save one gas stop on the trip.

 

I think your 91 got contaminated with water either by you or at the pump or even just condensation and the ethanol helped to dry it out. Higher octane will never harm an engine. It will just have a bit less power if there is no way for it to make use of the extra octane.

Lower octane in an engine that is designed for high will do damage.

 

I did one have some leftover 130 octane racing gas, that I dumped in my truck for proper disposal, the computer seemed to like that a lot, but the truck developed a squeak in the tires that went away as soon as that gas was used up. and the exhaust smelled like candy......... Ahhh I miss that smell........

[BlueSky]

Summer of 2014, I worked a job that was about 283 miles from home, so I rented an apt and drove home on the weekends. I have a Superchips tuner for my 2005 Dodge Magnum Hemi car that allowed me to tune the engine for 87 octane or 91. I was using so much gas at that time that I tuned it for 87. According to my rough calculations, I did get a little better fuel mileage tuned for the 91 but I was saving about $12/week running 87. But, my car has MDS which shuts off 4 cylinders when cruising to save fuel. Driving down I95 in South Carolina at 80mph with the cruise set, it didn't take much of an incline for the computer to switch the 4 cylinders back on. I thought it was missing at first before I realized that it was switching the 4 cylinders off and on. That demonstrated a slight hp/torque decrease in the 87 tune. I set it back to a 91 tune afterwards. I like the tuner because it did improve the throttle response noticeably and increased the hp/torque by 12hp/15 ft. lbs. according to the Superchips site and it felt like that was about right. The site has a dyno graph for my engine showing the results.

[Kretz]

It is kinda puzzling isn't it.` I live on an island and there is some extra humidity which might make ethanol gas more prone to collecting water. Perhaps the people who have difficulty with ethanol live in an area of even higher humidity. I ride my bike every day and it will get a little ****ty in two or three weeks but my lawn mower can sit for six months and still start on the second pull.

 

You live just across the pond from me so just use regular 87 like I do and don`t worry about it damaging your bike`s engine cuz it won`t.

 

Yes maybe you're right Camos. I worry too much.

I know a number of friends who run 87 but who will fill every 3rd or 4th tank with higher grade. I think I'll revert to 87 & just use an anti ethanol additive occasionally as has been suggested.... Now which one of those is best?

[Kretz]

Flyinfool it's amazing how that much higher grade fuel gave you squeaky tires. You must have spilled some of it on them!

[vzuden]

People tend think that just because they pay more, it is better. Higher octane is actually poorer quality and cheaper. The oil companies can charge more for it because those with high compression engines don't have a choice and also the general public focuses on the regular grade pricing because that is where the higher volume of sales are. It boils down to charging what the market will bear.

 

There is a website you can go to that will list all stations in your area that are selling non-ethanol. We have a few here and that is what I use in my lawn mowers for all of the above mentioned reasons.

[Dragonslayer]

Might just be you picked up some water or something in the old gas and refreshing it alone did the job,, I too highly doubt the "fix" had much to do with Octane level or the blend. Like some others on here - I stay away from high octane levels and just run the cheaper 87.. Funny thing, when traveling out west like we currently are I find a LOT of 85 Octane - always have.. I have ran that stuff alot while CTFW and never been dissatified with it - nary a ping one and I am usually loaded up pretty good and a passenger in the rear saddle..

Storage methods vary like oil preferences IMHO.. Personally, if I am gonna store for more then a month I either fuel em up full and start em at least one a month and run em till they are up to operating temps (ALWAYS loved doing this with my snowmobiles too - nothing like the sweet sound of a Thundercat or a Mach Z during the heat of summer) or I do the full stage storage maintenance including fogging the motor and draining the carbs.. Fact is,, what Kretz is describing is a classic from the world of which I came. I had wayyy more customers with machines that hadnt been started for a few months come to me, able to start em on the choke circuitry but unable to get to stay running than I care to think about. Carb cleaning was a normal course of doing business back in the day.. The smaller engines were always the worst because their orfices/jets are smaller and plug easier..

Frankly Kretz,, I say ya done got lucky,,,, take it back,, maybe not cause now ya gotta go cut your grass

I'm with Puc on this one, ethanol is not the only carb villain with small gas engines. Moisture and dirt and debris can be others assuming that fresh gas is introduced often enough that the old gas does not break down and leave varnish like deposits in the carb. On the bike if it sits for a long period I will usually top the tank off add gas treatment, close the gas cock off and allow the running bike to run out is gas.

For the mower, change the gas filter, fresh gas, check air filter and spark plug and you should be good for the season.

[steamer]

Back when the gov. made it mandatory to add ethanol to all gas, I was working for a John deer dealer. The first spring after the change we had 4 times the number of tractors, mower and small handheld machines come into the shop that would not run or ran poorly. The tech's were pulling carbs to find them all gummed up. We made a lot of money over the next few years in just cleaning carb's. One of the tech's decided to try something else other then pulling carb's...Sea foam. After that every morning you would find a dozen or more mowers and tractors sitting out back all running and smoking with a good dose of seafoam in them. Worked almost every time. Made a lot of money just sitting around watching them smoke.

[baylensman]

Back to the original poster. I sold SEARS craftsman mowers for years. I eventualy ran the lawn and garden department. Every time I heard a salesman make the statement "use Premium fuel its better" I'd send him upstairs to the training room and have him reread the module on Mower care. They'd always come back and ask why, I'd explain what I'd heard. They would look sheepish and say Okay I understand now.

 

The slower burn rate of Premium and semi premium fuels are especially apparent on engines with out adjustable timing. The biggest problem is that some unburnt fuel is trapped after the power stroke and before the exhaust valve fully opens leaving SOOT on the valves and cylinder head. I've actually pulled motors apart that the exhaust valve wouldn't close completely allowing oil to drip into the cylinder during storage.

 

The problem is similar in bikes. Most motorcycles engines are "static" timed and not adjustable. Now higher performance cars with Higher compression ratios often require premium fuel to prevent detonation during the compression stroke, and to allow for more initial advance in the timing signal to the plug. meaning the explosions at maximum power on the down stroke of the piston. to accomplish this the "burn must start sooner in the up stroke.

 

To dispel another myth Premium Fuels do contain Ethanol in most places ( two or three states ignore the federal mandate and don't require ethanol) in the US unless labeled Ethanol free. I understand the in Canada it varies by province, in some Premium does not have ethanol in others it does.