Old gas, what effect will it have on SRX

R

rlbock

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Saline, MI
I have a like new SRX and it came with some old fuel in the tank, not sure how old but probably at least 12 months old, added 4 fresh gallons to the tank and the issue i'm seeing is it is running hot and lean. I'm thinking the gas is the issue, carbs have been cleaned, do you agree that the old gas would cause these symptoms? Thanks for your input.
 
When fuel gets old, the octane decreases. With too low of octane, you will experience detonation. Do yourself a favor, drain it, throw that gas in your truck, and put fresh premium fuel in the sled. Don't take chances with fuel....you'll end up coming home on the trailer.
 
it weird octane decrease but have u ever try to light up old gaz ....its harder to lighter up
 
valin said:
As gasoline ages, the flammable properties will evaporate, making it harder to ignite.
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so if its harder to ignite its better for detonation .......................... :o|
 
Lower octane is never better for detonation. The definition of octane is the resistance to burn. The higher the octane, the harder it is to burn completely.
 
valin said:
Lower octane is never better for detonation. The definition of octane is the resistance to burn. The higher the octane, the harder it is to burn completely.[/QUOTE

i know higher octane resist to burn ..but if the gaz is old it is hard to burn so it must be good for detonation ..or maybe it will cause other problem cause it will be to hard to ignite like running to mutch octane went a motor doesnt need it... ......but i really agree old gaz should be pump out for fresh gaz ;)!
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I have seen old gas stick valves in a lawn mower & a chevy blazer plow truck. It's like it lost all it's lubrication ability. Not to mention the detonation. Look at octane like the bang-ability, lower octane ignites & burns very fast, so any pre-ignition is terrible. Higher octane burns slower & longer therefore more resistant to pre-ignition & detonation. I dis-agree with old gas being hard to burn, I have burned stale gas on bonfires & it is almost explosive.
 
ottawaair said:
I have seen old gas stick valves in a lawn mower & a chevy blazer plow truck. It's like it lost all it's lubrication ability. Not to mention the detonation. Look at octane like the bang-ability, lower octane ignites & burns very fast, so any pre-ignition is terrible. Higher octane burns slower & longer therefore more resistant to pre-ignition & detonation. I dis-agree with old gas being hard to burn, I have burned stale gas on bonfires & it is almost explosive.
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just try to ignite it went its cold .....it all depend how old it is.....for sure old gaz is crappp for engine
 
Gas left in an open container (open to atmosphere-like the gas tank) will loose it's lite ends/vapors = ability to ignite... todays gas seems to go bad quicker than ever before.
 
Gasoline, unlike diesel fuel, is unstable when it is placed under pressure. The octane stabilizes the reaction to pressure. The more compression created in the combustion chamber the more likely lower octane gasoline is to explode before the spark hits it. 2 stroke engine typically have higher compression which is why you need to burn premium hier octane gasoline, at least 91 octane.

However, gasoline burn better when it is turned into a vapour. Untreated gasoline has a certain amount of what is called "light ends" in it, light ends increase the ability of the gasoline to form a vapour. When gasoline is produced for internal combustion engines it is treated to up the amount of light ends but as the gasoline sits around the light ends evaporate. Gasoline fuel stabilizers like Stabil or what have you help the gasoline sit around longer while keeping the light ends and also to increase the amount of time you can leave the fuel sitting around before it separates and starts leaving varnish deposites.

I don't think the octane rating will decrease with time, but the ability of the fule to turn into a vapour and burn in an internal combustion engine will decrease. In other words you can still squeeze the fuel to 11:1 compression with out a premature compression ignition, but since the gasoline engine ignites the fuel by applying spark to the fuel vapour it is the ability of the fule to vapourize that will determine the explosion. Thus light ends in the fuel are needed.

too much time on my hands here. I apologize for being a know it all.
 
Replace the fuel, it is bad. Clean the carbs too, maybe some varnish build up in the jets.

You can in fact extinguish cigarette in a bucket of gasoline as long as you don't light up the vapours which will be present close to said bucket.

Trust me, I am an idiot.

I bet she run great. How fast have you had it going ?
 
valin said:
When fuel gets old, the octane decreases. With too low of octane, you will experience detonation. Do yourself a favor, drain it, throw that gas in your truck, and put fresh premium fuel in the sled. Don't take chances with fuel....you'll end up coming home on the trailer.
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where do you have this information from ????

btw that cant be true!
 
Sleigher said:
I don't think the octane rating will decrease with time, but the ability of the fule to turn into a vapour and burn in an internal combustion engine will decrease. In other words you can still squeeze the fuel to 11:1 compression with out a premature compression ignition, but since the gasoline engine ignites the fuel by applying spark to the fuel vapour it is the ability of the fule to vapourize that will determine the explosion. Thus light ends in the fuel are needed.

too much time on my hands here. I apologize for being a know it all.
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I believe you contradict yourself. Gasoline in a vented tank will have evaporative loss like as you mention. The evaporation of light ends decreases a gasoline's antiknock index.
 
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