"I just put fresh gas in it"

[Spike60]

A simple lesson that might save guys some grief.

Just worked on 3 pcs for a friend. 372, 572, and a 525 pole saw. All 3 had run issues. All 3 had some water in the fuel. Pole saw had old and cloudy fuel that took a while to even start to separate. 372 had nice clear blue fuel that separated quickly from the puddle of water in the bottom of the tray. 572 wasn't as bad, but still had enough to cause some hiccups. 

The usual refrain of "I just put fresh gas in there" was followed by my usual "was there already some gas in there?" For the past 30 years, there are 3 variations of essentially the same answer to that question: there might have been, I didn't think of that, or I don't know.  

You cannot solve a fuel problem by adding fresh fuel to bad fuel. Best analogy I can think of is you can't un-spoil bad milk in the fridge by adding fresh milk to it. (Think how that would taste)

You have to dump it. Which has always been the 1st thing I do when working on a saw to answer the question of "what is this thing trying to run on?" If it's crap, it's also a good idea to pull the fuel line off the carb so it will drain out. Modern saws with primers will at that point flush the carb itself pretty good. 

I could go on, and likely will in the next post. Countless stories. 

[thecfarm]

I used to work in a hardware store.
people would make a circle with their thumb and finger and say, About this big around.  

[WLzM1A]

  I ALWAYS dump the gas out when I'm done and run it till dry.  A saw not running right does nobody any good

[Spike60]

Had an example of what I call the "last fill" syndrome yesterday. Guy we call Firewood John has a medium size operation. Couple helpers. They typically run 4 saws during the day. Tank through each then grab another. Three 372's and a 385. Gas can awareness never been a strong point with those guys. So, I get the 385 and it's loaded with water. John insists that it can't be true because the other saws all ran fine on the same fuel. 

Some discussion follows and we confirm that the 385 got the last gulp of gas from that fuel can. Water tends to stay in the bottom of the gas can and not become a problem until you empty the can in which case the water all goes in with the last fill. No doubt obvious to most of you guys, but it's amazing how many times I've seen that over the years. 

[Al_Smith]

I'll mix up a 2 gallon gas can with 32 to 1 ratio and use it until it gets down to an inch or two from the bottom .Dump the remaining gas into my Ferguson tractor then start anew with fresh gasoline .The old Fergy doesn't usually care if the gas has a slight amount of condensate in it .It just might sputter a little bit . 
A lot of people don't know it but real old low RPM tractor engines used a water injection system to prevent foul up running low grade fuel .A little chainsaw engine doesn't respond that way .
Slightly off topic but during WW 2 on both the Allison and Rolls Royce engines used on the P-51 mustang it had what they dubbed as WEP."war emergency Power ".A water or water  ethanol injection mix that boosted the power to often times double the normal power .It got some out of trouble but caused extra wear and tear on the engine .It was only to be used about 5 minutes at a time .The power was nice but with a broken crankshaft  wouldn't be very much of a benefit .                                                                             

[Spike60]

Nice history Al, thanks. Broken crank in a dogfight at 15, 000 ft would be somewhat more of an inconvenience than the stuff we complain about with our saws, wouldn't it? 

[YellowHammer]

Some advanced turbine engines still use water injection to get a quick boost, I designed and tested a couple, one was an Allison/Rolls Royce Tactical Turbojet, the other a Noel Penny.  The water expands violently much like in an old steam engine when it hits the hot section of the engine, so provides a good bit of additional mass and volume.  The expanding water cools the engine some, so the fuel flow rate must be increased to compensate so engine temps can remain constant and balanced.  In some cases we added alcohol to the mix to supplement the fuel, if the fuel pump was maxed out.  If done correctly, it doesn't damage the engine, if the engine components are rated for the additional power generated. If not done correctly, it's a pretty exciting day when the Fire Department rolls up to put out all the little brushfires from the exploding engine.

I remember once I was flying commercial and the lady next to me was freaking a little because we were in a bad rain storm, and she kept thinking the rain was going to put the engines out and I said nope, the pilot has more power than usual, and he's happy, so not a problem.  She didn't believe me so I reached into my carry on and pulled out a turbine engine design handbook I always carried with me, and she actually read that section.  She asked who I was and said, "Nobody, just an Alabama country boy."

It was a pretty cool memory, I hadn't even thought of it until Al's post.



 

[Old Greenhorn]

Nice history Al, thanks. Broken crank in a dogfight at 15, 000 ft would be somewhat more of an inconvenience than the stuff we complain about with our saws, wouldn't it?

The pilot would likely complain louder, but the chainsaw owner would complain longer.

[Old Greenhorn]

I am just one old guy that can only run one saw at a a time and not very long at that on any given day. I spend more time handling than cutting. So I only mix one gallon at a time and when that gets low I mix more before I go back out the next day. Sometimes that can will last a few weeks, sometimes a few days. On the very rare occasions that i use it up during the day, it always means I am working with others on a large job and running my saw a lot. It also means there is a 5 gallon can of mix so I use some of their gas, which I find to be cheaper anyway.   Mostly I run the 350 which doesn't use much gas, but if I am running my 562 I can go through some fuel for sure in comparison.
 Knock on wood, I have never had water in my gas and I have never straight gassed a saw yet.

[Al_Smith]

A tad more trivia about water injection which I first saw on a John Deere model D .That's I thnk 503 cubic inch two cylinder low RPM .I met an elderly gent who told me stories during the great depression they ran that old D nearly 24 hours a day using lanterns at night and using well head crude oil and water injection .They made it through those tough times but totally  wore the poor old tractor out .The deal was they started it on gasoline and closed the radiator shutters and ran the temp up to around 190 degrees then switched it over to the crude oil .It was in southern Ohio that had thinner crude oil than the sour crude we have in the northern portion that looks like creosote . I'd imagine running that thing in July with a thermal siphon zero pressure system was like riding around on a steam bath .It's no wonder why old pictures show skinny people .

[GAB]

To: @Spike60:
Question - Was the fellow's using a metal gas can?
Is it possible that the water was from the can being in the cold and from moisture condensat forming inside the can in cold weather?
As an FYI ,and you may already know this, I use the highest octane non-ethenol gas I can find and I put the first 5 gallons in my truck.  Yes you can set the pump to a particular setting however for a bit you will be pumping what the last person that used that pump purchased.  Not knowing how much fuel is in the line before it starts spitting out what I am purchasing is why I put the first 5 galons in my truck.  I realize 5 gallons might be overkill but it is easier to keep track of the meter as I usually do more than one can at a time.
GAB

[barbender]

Our local station's pumps have seperate lines for each product, so you don't have to worry about getting some amount of the last guys fuel.

[Spike60]

To: @Spike60:
Question - Was the fellow's using a metal gas can?
Is it possible that the water was from the can being in the cold and from moisture condensat forming inside the can in cold weather?
As an FYI ,and you may already know this, I use the highest octane non-ethenol gas I can find and I put the first 5 gallons in my truck.  Yes you can set the pump to a particular setting however for a bit you will be pumping what the last person that used that pump purchased.  Not knowing how much fuel is in the line before it starts spitting out what I am purchasing is why I put the first 5 galons in my truck.  I realize 5 gallons might be overkill but it is easier to keep track of the meter as I usually do more than one can at a time.

Those guys use plastic cans. But, they also leave the spouts exposed, the caps are nowhere to be found. Take em in when there's weather? All the way over to the shop? (Anout 50 ft)

I do the same pump procedure as you do for most places. One does have a separate pump for non ethanol, but I usually like to throw a few gallons in the truck anyway. 

[Magicman]

I hate to 'bottom up' any fuel jug and empty the dregs into an engine's fuel tank.