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What has happend to gas when it gets old and starts to affect engine performance?



 
 
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  #1  
Old May 10th 17, 09:05 PM posted to rec.autos.tech
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Default What has happend to gas when it gets old and starts to affect engine performance?

What is actually happening to the gas? Can it be treated? And can you cause harm to your engine by running it with this type of gas? Lenny
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  #2  
Old May 10th 17, 11:22 PM posted to rec.autos.tech
Scott Dorsey
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Default What has happend to gas when it gets old and starts to affect engine performance?

In article >,
> wrote:
>What is actually happening to the gas?


Gas is a mixture of all kinds of stuff. The light hydrocarbons evaporate.
The medium hydrocarbons link up with one another and form varnish. Now that
we have ethanol in gas instead of lead, much of the ethanol evaporates and
what doesn't evaporate deliquesces and pulls water from the air.

So what you wind up is a uniform mixture of varnish, heavier hydrocarbons,
and water.

> Can it be treated?


Not really. You can dilute it way down with good gasoline and burn it
a little bit at a time to get rid of it.

There are pretreatments that will prevent some of the breakdown if you
have to store gasoline for a whole, but they aren't as effective as they
were in the pre-ethanol days.

> And can you cause harm to your engine by running it with this type of gas? Lenny


You bet. Varnish clogs up the fuel filter, it clogs up the injectors, water
causes rust in the tank and in fuel lines which clogs up the filter and the
injectors. The car winds up missing, running lean, you burn a valve trying
to keep it running.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #3  
Old May 11th 17, 12:59 AM posted to rec.autos.tech
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Default What has happend to gas when it gets old and starts to affectengine performance?

On Wednesday, May 10, 2017 at 4:05:15 PM UTC-4, wrote:
> What is actually happening to the gas? Can it be treated? And can you cause harm to your engine by running it with this type of gas? Lenny


Thanks for the great explanation Scott. This vehicle had been sitting for three years with a full tank of gas in it.
It started right up but runs like crap under load. When you mentioned adding good gas to it and burning it off slowly did you mean just keep adding to it until you've done a complete transfusion to get rid of it or did you mean after you've pumped all this crap out of the tank? Lenny
  #4  
Old May 11th 17, 04:11 AM posted to rec.autos.tech
Andy
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Default What has happend to gas when it gets old and starts to affectengine performance?

On Wednesday, May 10, 2017 at 6:59:17 PM UTC-5, wrote:
> On Wednesday, May 10, 2017 at 4:05:15 PM UTC-4, wrote:
> > What is actually happening to the gas? Can it be treated? And can you cause harm to your engine by running it with this type of gas? Lenny

>
> Thanks for the great explanation Scott. This vehicle had been sitting for three years with a full tank of gas in it.
> It started right up but runs like crap under load. When you mentioned adding good gas to it and burning it off slowly did you mean just keep adding to it until you've done a complete transfusion to get rid of it or did you mean after you've pumped all this crap out of the tank? Lenny


If it's been sitting for 3 years, take it to your mechanic and have him drain the tank.

Andy

  #5  
Old May 11th 17, 01:43 PM posted to rec.autos.tech
Scott Dorsey
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Default What has happend to gas when it gets old and starts to affectengine performance?

> wrote:
>Thanks for the great explanation Scott. This vehicle had been sitting for t=
>hree years with a full tank of gas in it.=20
>It started right up but runs like crap under load.


Well, if you're lucky the only thing you've wrecked is the fuel filter.
Dump the fuel, change the filter and see how it goes. Don't be surprised
if the fuel pump fails in the next few thousand miles too, so have a spare.

It wouldn't hurt to pull the injectors and check the screen filters inside
each one too. If you have one injector partly clogged, you wind up with one
cylinder running leaner than the others which is a recipe for a burned valve.

>When you mentioned addin=
>g good gas to it and burning it off slowly did you mean just keep adding to=
> it until you've done a complete transfusion to get rid of it or did you me=
>an after you've pumped all this crap out of the tank? Lenny


I mean draining the tank, and once you have the thing running well and have
run a few good tanks of gas through it, THEN burning small amounts of the
bad gas. Take 20 gallons of good gas and one gallon of the bad gas.

If you dilute it down enough it won't be too horrible, and it saves you from
having to pay a fortune in disposal fees to get rid of it.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #6  
Old May 12th 17, 11:11 AM posted to rec.autos.tech
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Default What has happend to gas when it gets old and starts to affectengine performance?

On Thursday, May 11, 2017 at 6:22:51 AM UTC+8, Scott Dorsey wrote:
>
> You bet. Varnish clogs up the fuel filter, it clogs up the injectors, water
> causes rust in the tank and in fuel lines which clogs up the filter and the
> injectors. The car winds up missing, running lean, you burn a valve trying
> to keep it running.
> --scott


I have run dual-fuel cars for many years. They start on gasoline, but soon
switch to LPG. So little, that a tank of gasoline would last for years.
However, stale fuel would stuff the fuel pump eventually. Did not find any
other damage. I would have thought that evaporation of lighter fractions
(pentane, hexane?) would affect cold starts, but that did not seem to occur.
  #7  
Old May 12th 17, 01:41 PM posted to rec.autos.tech
Scott Dorsey
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Default What has happend to gas when it gets old and starts to affectengine performance?

> wrote:
>On Thursday, May 11, 2017 at 6:22:51 AM UTC+8, Scott Dorsey wrote:
>>
>> You bet. Varnish clogs up the fuel filter, it clogs up the injectors, water
>> causes rust in the tank and in fuel lines which clogs up the filter and the
>> injectors. The car winds up missing, running lean, you burn a valve trying
>> to keep it running.

>
>I have run dual-fuel cars for many years. They start on gasoline, but soon
>switch to LPG. So little, that a tank of gasoline would last for years.
>However, stale fuel would stuff the fuel pump eventually. Did not find any
>other damage. I would have thought that evaporation of lighter fractions
>(pentane, hexane?) would affect cold starts, but that did not seem to occur.


That's kind of cool actually! Maybe running on LPG cleans the injectors and
lines out? How much of the fuel system is actually shared between both fuels?
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
  #8  
Old May 13th 17, 10:39 AM posted to rec.autos.tech
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Default What has happend to gas when it gets old and starts to affectengine performance?

On Friday, May 12, 2017 at 8:42:00 PM UTC+8, Scott Dorsey wrote:
> <pedro1492.com> wrote:
> >On Thursday, May 11, 2017 at 6:22:51 AM UTC+8, Scott Dorsey wrote:
> >>
> >> You bet. Varnish clogs up the fuel filter, it clogs up the injectors, water
> >> causes rust in the tank and in fuel lines which clogs up the filter and the
> >> injectors. The car winds up missing, running lean, you burn a valve trying
> >> to keep it running.

> >
> >I have run dual-fuel cars for many years. They start on gasoline, but soon
> >switch to LPG. So little, that a tank of gasoline would last for years.
> >However, stale fuel would stuff the fuel pump eventually. Did not find any
> >other damage. I would have thought that evaporation of lighter fractions
> >(pentane, hexane?) would affect cold starts, but that did not seem to occur.

>
> That's kind of cool actually! Maybe running on LPG cleans the injectors and
> lines out? How much of the fuel system is actually shared between both fuels?
> --scott
>
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."


I doubt any. Older systems just had a mixer next to the throttle. Since
about 2005, sequential injected systems are needed to pass emission standards.
So there are two sets of injectors. I doubt anybody made a flexfuel
system for LPG, like with E85.
The only liquid-injection systems I know of were dedicated LPG.
But I imagine if you could force propane/butane though the fuel system
it might work as a harmless cleaning solvent?
  #9  
Old May 16th 17, 12:39 PM posted to rec.autos.tech
Scott Dorsey
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Posts: 3,914
Default What has happend to gas when it gets old and starts to affectengine performance?

> wrote:
>On Friday, May 12, 2017 at 8:42:00 PM UTC+8, Scott Dorsey wrote:
>> >I have run dual-fuel cars for many years. They start on gasoline, but soon
>> >switch to LPG. So little, that a tank of gasoline would last for years.
>> >However, stale fuel would stuff the fuel pump eventually. Did not find any
>> >other damage. I would have thought that evaporation of lighter fractions
>> >(pentane, hexane?) would affect cold starts, but that did not seem to occur.

>>
>> That's kind of cool actually! Maybe running on LPG cleans the injectors and
>> lines out? How much of the fuel system is actually shared between both fuels?

>
>I doubt any. Older systems just had a mixer next to the throttle. Since
>about 2005, sequential injected systems are needed to pass emission standards.
>So there are two sets of injectors. I doubt anybody made a flexfuel
>system for LPG, like with E85.
>The only liquid-injection systems I know of were dedicated LPG.


Makes sense. Then all that I can think of is that the system was designed
to deal with old gas since the manufacturers expected you to be driving like
you do?
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
 




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