Possible new bad gas. What should I do?

[bwalker]

My thought was that less dense fuel in the winter would give lower mpg. I doubt it would cause more than a few percentage points difference, not 5mpg in a 35-40mpg car.

For @Sidecarflip the mpg difference is likely more due to colder temps causing the car to take longer for the car to get to full operating temp, and running in the less efficient open loop mode longer. Also, cooler denser air makes turbo engines happy, when the air going into the turbo is cooler, the air coming out is cooler, and the intercooler also works more effectively. All that means more air going into the engine, so more fuel has to be burned to maintain the programmed air/fuel ratio, impacting mpg. More power, though. Are you measuring mpg by doing calculations at the pump, using the car's computer, or just seat of pants?

Less dense fuel is a small part of it, running in open loop mode to heat the cat is a small part of it and alot of it is the change in air density.
For example a dirt bike would require a main jet 5+ numbers richer when going from the 90's to the 10's.

 

[lone wolf]

Modern fuel injected vehicles digest bad gas just fine.
That's assuming the gas in question is bad. I bet there is nothing wrong with it other than the RVP not being suited to warm weather.

So what do you think about the 500I with fuel injection, would that help with crap fuel over carbed saws?

 

[JoshNY]

Double check on www.pure-gas.org
They compile a listing of ethanol free stations all over the country.

 

[OM617YOTA]

Double check on www.pure-gas.org
They compile a listing of ethanol free stations all over the country.

There's been issues with that site. Call before you go.

 

[bwalker]

So what do you think about the 500I with fuel injection, would that help with crap fuel over carbed saws?

I am not laid eyes on the 500I injection set up, but it's likely it would in cases where volatility is an issue. Diaphragm carbs as used in chainsaws are known to have issues with high volatility. Floatbowl carbs as found on small engines practically never have the same issue.
What a 500I won't do as compensate for fuel that's lost its octane. A auto engine will do this.

 

[OM617YOTA]

I am not laid eyes on the 500I injection set up, but it's likely it would in cases where volatility is an issue. Diaphragm carbs as used in chainsaws are known to have issues with high volatility. Floatbowl carbs as found on small engines practically never have the same issue.

Is that because diaphragm carbs suck fuel from the tank into the carb, and lower pressure increases the chances of vapor lock with a fuel with too much vapor pressure for the operating temp, while float carbs run under pressure(even if very slight) right up until the fuel is sucked out of the bowl and into the jets and air stream into the motor?

 

[Seachaser]

There's been issues with that site. Call before you go.

It is a complete miss around us. Places that have it are not on there and places it says has it, doesn’t.

 

[bwalker]

It is a complete miss around us. Places that have it are not on there and places it says has it, doesn’t.

For starters gas stations often or even most of the time don't buy their fuel from the same refinery. Then you have the fact that quality is all over the place.
In my home state fuel pumps will often state the fuel has ethanol, but it often doesnt do to waivers for short supply.

 

[bwalker]

Is that because diaphragm carbs suck fuel from the tank into the carb, and lower pressure increases the chances of vapor lock with a fuel with too much vapor pressure for the operating temp, while float carbs run under pressure(even if very slight) right up until the fuel is sucked out of the bowl and into the jets and air stream into the motor?

That could be it, but I'm honestly not sure.

 

[ace4059]

I’ll have to read through the posts and answer any questions you asked me at a later time.

Here are pictures of the 400
Pics of MS 400 CM piston and cylinder wall

 

[ace4059]

Here is the MS 261 CM
It has two vertical lines on the back wall by the intake port which I can’t get the camera angle to take the picture of it.


MS 261 CM

 

[lone wolf]

I don't see any real damage, do you?

 

[ace4059]

Here’s the replies to the questions I see for me over the last two pages.

I put some regular gas that’s in question in a glass mason jar. I didn’t get home from Ft. Worth until 2am. Now I’m heading to Amarillo. I won’t be back home for a few days. I took a photo and I’ll take another one of the gas when I return. But it looks good now.

Yes, I use the pure gas website. It is accurate around where I live.

As far as if there is any damage? That’s really why I posted photos. The shop here in town thinks the lines on the back of the cylinder of the 261 is caused from the pin at the split that holds the rings. You can’t see the vertical lines in that cylinder because I can’t get the correct angle with the camera. The shop said they would be more concerned with what looks to be pitting on the cylinder.

On the 400, you can see the polished marks that look like vertical lines on the back of the cylinder. The tech said that looks like dirt ingress and damaged the cylinder.

Techs said they can’t tell if it has “bad gas” damage. That’s why at this point I am asking for other opinions.

 

[dboyd351]

Isn't non ethanol the cure? Only if it doesn't have water in it. I find just as much water in both.
Is t

I am sure either type of gas is capable of having as much water, but what happens to the water is entirely different.
In non-ethanol fuel, the water seperates relatively quickly and completely. If you have a filter like a 10 micron Racor with a clear plastic bowl and a drain you can keep running til the tank is empty by repeatedly draining the bowl.
With fuel containing ethanol, the water mixes with the gas because the ethanol absorbs water. After the "gas" reaches the point that the ethanol has absorbed all the water it can keep in suspension you get phase seperation where a gel like substance is formed that can totally plug up the gas passages.
Regardless of whether ethanol and non-ethanol fuel have the same amount of water, the effect on how your engine runs is much different.

 

[thenne1713]

Modern fuel injected vehicles digest bad gas just fine.
That's assuming the gas in question is bad. I bet there is nothing wrong with it other than the RVP not being suited to warm weather.

I too encountered old, bad gas from neighbor who borrowed tiller my tiller and it wud not start; I removed gas, removed water, tried again, still no hit/ no start; removed and installed MY gas and it fired/ ran fine first pull. I 100% think you are wrong; at MIN, on multi-cylinder injected, I suspect wud generate 300 codes.

 

[thenne1713]

Here’s the replies to the questions I see for me over the last two pages.

I put some regular gas that’s in question in a glass mason jar. I didn’t get home from Ft. Worth until 2am. Now I’m heading to Amarillo. I won’t be back home for a few days. I took a photo and I’ll take another one of the gas when I return. But it looks good now.

Yes, I use the pure gas website. It is accurate around where I live.

As far as if there is any damage? That’s really why I posted photos. The shop here in town thinks the lines on the back of the cylinder of the 261 is caused from the pin at the split that holds the rings. You can’t see the vertical lines in that cylinder because I can’t get the correct angle with the camera. The shop said they would be more concerned with what looks to be pitting on the cylinder.

On the 400, you can see the polished marks that look like vertical lines on the back of the cylinder. The tech said that looks like dirt ingress and damaged the cylinder.

Techs said they can’t tell if it has “bad gas” damage. That’s why at this point I am asking for other opinions.

<<vertical lines on the back of the cylinder. The tech said that looks like dirt ingress and damaged the cylinder.>> Another telltale of dirt bypassing filter is mud in the venturi of carb vs CLEAN

 

[Lightning Performance]

For starters gas stations often or even most of the time don't buy their fuel from the same refinery. Then you have the fact that quality is all over the place.
In my home state fuel pumps will often state the fuel has ethanol, but it often doesnt do to waivers for short supply.

I read a bunch about the supply chain last week. That made myself and two others ready to make the switch to boat fuel. It doesn't have that variable to eliminate.

 

[stihltech]

Water in a saw is never ok. Water in ethanol is worse. Nope, bad either way. Use it up and minimum 89 octane. Check it with a glass jar.
Water is the cause. Lean running and corrosion are the effect
Us it up quickly. No magic wand.

I am sure either type of gas is capable of having as much water, but what happens to the water is entirely different.
In non-ethanol fuel, the water seperates relatively quickly and completely. If you have a filter like a 10 micron Racor with a clear plastic bowl and a drain you can keep running til the tank is empty by repeatedly draining the bowl.
With fuel containing ethanol, the water mixes with the gas because the ethanol absorbs water. After the "gas" reaches the point that the ethanol has absorbed all the water it can keep in suspension you get phase seperation where a gel like substance is formed that can totally plug up the gas passages.
Regardless of whether ethanol and non-ethanol fuel have the same amount of water, the effect on how your engine runs is much different

 

[Lightning Performance]

Water in a saw is never ok. Water in ethanol is worse. Nope, bad either way. Use it up and minimum 89 octane. Check it with a glass jar.
Water is the cause. Lean running and corrosion are the effect
Us it up quickly. No magic wand.

That fact that you're burning water in the eth is the part most people miss. Water cools but not in place of fuel in the whole burn cycle. It's always lean with eth. So add water and the mix gets leaner as the octane rating falls from lose of light ends available to burn. That E20 or more that got me gladly accepted plenty of water well beyond what E10 will absorb. It smells like almost nothing now. Likely a bad mix or something.

 

[bwalker]

I read a bunch about the supply chain last week. That made myself and two others ready to make the switch to boat fuel. It doesn't have that variable to eliminate.

Non ethanol rec fuel is just as variable. Premium has is blended of the same components just at different ratios.