I think y'all might enjoy this. Hopefully you'll find it useful; just goes to show how today's fuel quality has changed-drastically.
Customer brings me a boat today; says it's been sitting, yaddya yaddya. The norm. Get it running he wants to go fishin'. Don't blame him, on a day like today. First thing I do is pull a fuel sample by disconnecting the fuel line from the carburetor and then use the boat's primer bulb to force fuel from the line and into a clear jar. Came out clean. I set the jar in the shop; was about 1/2 pint of fuel at the most. Pics show it, in a little glass jar. I lost the lid long ago. This is 100% fuel with zero ethanol content (I use test strips at work to verify), and no premix as this is a 4 stroke. He says he just bought the fuel and I don't doubt him. There's only ONE station locally that sells "straight gas" and from my own experience, it's got to be 93 octane to get it 100%. The 87 and 89 always had a little bit of ethanol in it, no more than 4% is what I've seen by testing over the last couple years.
First pic, I had just pumped the fuel into the jar. This was at 1:48pm when I took the pic.
Second pic, was exactly 2 hours and a minute later. 3:49pm, jar still sitting in the same spot, and nobody's touched it. That's moisture condensing in the jar, that's why the gas is cloudy. The jar was about 10 degrees cooler than when I first put the fuel in it! Evaporative cooling effect. I have a cool video to share too, if I can figure out how to get it from my phone to the PC.
Now what have we learned? How do we apply this knowledge? First thing's first. If you guys have noticed; over the last few years manufacturers have gone to low-permeation fuel tanks, that are more or less sealed up. That's why they swell; and the cheap ones swell and BREAK at the seam. Don't get a cheap tank. 6 gallons of fuel laying in the bottom of a hot boat is not my idea of fun; and if you're a smoker and out fishing while enjoying your nicotine, and your 6 gal tank busts, you're in for a big surprise. Anyway, a lot of folks have gotten the idea that it's better to use an older vented fuel tank. Well obviously our fuel is different than it was when tanks were vented like "the old days" (1990's and before), so in using a vented fuel tank, there stands a chance for evaporation. Based on what I'm seeing, it surely happens. Also, as it evaporates, it cools, and in humid climates, moisture will condense in the fuel-as seen by the jar test above. So, big deal right? Enter: Premix fuel.
Gas evaporates and; similar to water evaporting, not everything changes state. There's the chemicals left that are in the water, and with fuel there's the oil left, and other chemicals that don't evaporate. So now your fuel is junk. You started out at 50:1, and worst case scenario after a few weeks of sitting, 50% of the fuel evaporates. So you had 50:1 with 6 gallons, now you have 25:1 with 3 gallons; give or take. See a problem here?
Customer brings me a boat today; says it's been sitting, yaddya yaddya. The norm. Get it running he wants to go fishin'. Don't blame him, on a day like today. First thing I do is pull a fuel sample by disconnecting the fuel line from the carburetor and then use the boat's primer bulb to force fuel from the line and into a clear jar. Came out clean. I set the jar in the shop; was about 1/2 pint of fuel at the most. Pics show it, in a little glass jar. I lost the lid long ago. This is 100% fuel with zero ethanol content (I use test strips at work to verify), and no premix as this is a 4 stroke. He says he just bought the fuel and I don't doubt him. There's only ONE station locally that sells "straight gas" and from my own experience, it's got to be 93 octane to get it 100%. The 87 and 89 always had a little bit of ethanol in it, no more than 4% is what I've seen by testing over the last couple years.
First pic, I had just pumped the fuel into the jar. This was at 1:48pm when I took the pic.
Second pic, was exactly 2 hours and a minute later. 3:49pm, jar still sitting in the same spot, and nobody's touched it. That's moisture condensing in the jar, that's why the gas is cloudy. The jar was about 10 degrees cooler than when I first put the fuel in it! Evaporative cooling effect. I have a cool video to share too, if I can figure out how to get it from my phone to the PC.
Now what have we learned? How do we apply this knowledge? First thing's first. If you guys have noticed; over the last few years manufacturers have gone to low-permeation fuel tanks, that are more or less sealed up. That's why they swell; and the cheap ones swell and BREAK at the seam. Don't get a cheap tank. 6 gallons of fuel laying in the bottom of a hot boat is not my idea of fun; and if you're a smoker and out fishing while enjoying your nicotine, and your 6 gal tank busts, you're in for a big surprise. Anyway, a lot of folks have gotten the idea that it's better to use an older vented fuel tank. Well obviously our fuel is different than it was when tanks were vented like "the old days" (1990's and before), so in using a vented fuel tank, there stands a chance for evaporation. Based on what I'm seeing, it surely happens. Also, as it evaporates, it cools, and in humid climates, moisture will condense in the fuel-as seen by the jar test above. So, big deal right? Enter: Premix fuel.
Gas evaporates and; similar to water evaporting, not everything changes state. There's the chemicals left that are in the water, and with fuel there's the oil left, and other chemicals that don't evaporate. So now your fuel is junk. You started out at 50:1, and worst case scenario after a few weeks of sitting, 50% of the fuel evaporates. So you had 50:1 with 6 gallons, now you have 25:1 with 3 gallons; give or take. See a problem here?