Can fuel go off?
Discussion
If the Noble is not used for 6 months?
My mate's 2.5 GTO has a "flat spot" around 5,000 rpm which Mole Valley believed was the ECU which was then replaced but the problem remained.
Yesterday he filled with some BP Ultimate and the flat spot has improved but not gone. Any suggestions and does this sound like a fuel problem?
L
My mate's 2.5 GTO has a "flat spot" around 5,000 rpm which Mole Valley believed was the ECU which was then replaced but the problem remained.
Yesterday he filled with some BP Ultimate and the flat spot has improved but not gone. Any suggestions and does this sound like a fuel problem?
L
Yes petrol does go off. It absorbs water for one thing. Water forms inside fuel tanks as condesnation which is why you allways leave airplanes with tanks full and check the water trap before each day's flying. However a clean tankfull will rapily flush out the old so its not the explanation here.
Paul C
Paul C
Give Warren Scott at Shell Aussie a ring on +AUS 1300 134 205. He works for Shell and is cited on the Internet as saying this
"According to Shell Australia’s Technical Advice Centre Manager, Warren Scott, you can generally store fuel in a sealed container for around six months before it starts to deteriorate. This assumes it’s kept relatively cool and away from direct sunlight.
“But if the container is not properly sealed or it’s repeatedly opened, [fuel] will start to evaporate and you lose some of the light components in the fuel,” Mr Warren says.
Those light components include highly important butane. As these components are lost, the fuel loses its volatility. Mr Warren says this makes the car difficult to start.
In warm conditions, fuel is especially prone to oxidisation which causes lacquer and gums to form. As a result, the fuel turns dark in colour, loses its clarity and smells like paint stripper.
Gary Whitfield, Senior Fuel Chemist at BP Australia, says that in the right conditions, fuel can last up to 12 months. But once the container is opened, the fuel will start to degrade.
“Once the seal is broken, a vapour space is formed in the container and the fuel will start to deteriorate more rapidly,” he says.
Okay, so what about fuel that’s left in your car’s tank for a long period of time?
Mr Whitfield claims fuel in a car’s tank can last for up to four weeks before it becomes considerably denser. When this happens, the engine is effectively over-fuelled (without any change in injector pulse-width) and there’s an increased chance of carbon deposition onto spark plugs and inside the combustion chamber. This can cause driveability problems such as stutters and misses.
“Regular unleaded fuel will lose a small amount of octane over time but in our low-sulphur and high detergent Ultimate fuel it might increase very slightly. It might increase 1 RON in four weeks – but it’s not something I’d bother chasing,” he says.
“Keep in mind that typical variation in BP Ultimate is 98 – 100 RON while normal unleaded ranges between 91 – 93 RON.”
Mr Warren says that in most cases, it’s only when fuel is left in the tank for several months there’s the risk of engine damage. This is much more likely to occur in cars running dual LPG/petrol systems.
“By this time the fuel will have gone dark and gummy and can clag the fuel pump, filter and injectors,” Mr Warren says. It can also leave a lacquer deposit on the inside of the fuel tank which is difficult to remove.
In addition, it’s important to be aware that fuel brews – specifically fuel volatility - varies on a month to month basis. Standards vary from state to state but, generally, volatility is reduced during summer months to reduce evaporative emissions. Mr Whitfield says this typically makes the engine slightly harder to start but there is no change in octane.
Lachlan Riddel, proprietor of Gold Coast based tuning company ChipTorque, frequently dyno tests cars which have not previously been driven for several weeks.
“On the fuel mix we have in Queensland, I think fuel in a car’s tank is starting to go off in around three weeks,” Mr Riddel says. “We can tune a car, put it away for three of four weeks, come back to it and it will be either closer to detonation or less likely to make the same power.
“I think local fuel is brewed to reduce evaporative emissions in warm weather and, maybe because of that, fuel really goes crappy in eight to ten weeks. By that stage, the fuel is extremely prone to detonation.”
Interestingly, Mr Riddel hasn’t noticed the engine becoming harder to start but the effect on octane is pronounced.
Similarly, the General Manager of Melbourne’s Advanced Vehicle Operations, Steve Coates, believes fuel tends to go off in a car’s fuel tank quite quickly once it’s a couple of weeks old.
“After a couple of weeks not driving a car, I find that it will be closer to detonation than it was at the time of tuning on the chassis dyno,” he says.
“And the brand of fuel seems to make a difference as well – I find that Mobil and BP products are probably the best after being stored but Shell Optimax is really good when it’s new."
Clearly, there are some important factors to keep in mind when storing fuel in a container for several months or when parking your car for a few weeks.
Our recommendation is not to run the engine at high load with fuel that’s been in the tank for any more than three of four weeks and it’s a good idea to add at least 25 percent fresh fuel to the tank every few weeks. This will help ensure there are no fuel-related driveability problems or detonation and will reduce the chance of lacquer building up inside the tank."
"According to Shell Australia’s Technical Advice Centre Manager, Warren Scott, you can generally store fuel in a sealed container for around six months before it starts to deteriorate. This assumes it’s kept relatively cool and away from direct sunlight.
“But if the container is not properly sealed or it’s repeatedly opened, [fuel] will start to evaporate and you lose some of the light components in the fuel,” Mr Warren says.
Those light components include highly important butane. As these components are lost, the fuel loses its volatility. Mr Warren says this makes the car difficult to start.
In warm conditions, fuel is especially prone to oxidisation which causes lacquer and gums to form. As a result, the fuel turns dark in colour, loses its clarity and smells like paint stripper.
Gary Whitfield, Senior Fuel Chemist at BP Australia, says that in the right conditions, fuel can last up to 12 months. But once the container is opened, the fuel will start to degrade.
“Once the seal is broken, a vapour space is formed in the container and the fuel will start to deteriorate more rapidly,” he says.
Okay, so what about fuel that’s left in your car’s tank for a long period of time?
Mr Whitfield claims fuel in a car’s tank can last for up to four weeks before it becomes considerably denser. When this happens, the engine is effectively over-fuelled (without any change in injector pulse-width) and there’s an increased chance of carbon deposition onto spark plugs and inside the combustion chamber. This can cause driveability problems such as stutters and misses.
“Regular unleaded fuel will lose a small amount of octane over time but in our low-sulphur and high detergent Ultimate fuel it might increase very slightly. It might increase 1 RON in four weeks – but it’s not something I’d bother chasing,” he says.
“Keep in mind that typical variation in BP Ultimate is 98 – 100 RON while normal unleaded ranges between 91 – 93 RON.”
Mr Warren says that in most cases, it’s only when fuel is left in the tank for several months there’s the risk of engine damage. This is much more likely to occur in cars running dual LPG/petrol systems.
“By this time the fuel will have gone dark and gummy and can clag the fuel pump, filter and injectors,” Mr Warren says. It can also leave a lacquer deposit on the inside of the fuel tank which is difficult to remove.
In addition, it’s important to be aware that fuel brews – specifically fuel volatility - varies on a month to month basis. Standards vary from state to state but, generally, volatility is reduced during summer months to reduce evaporative emissions. Mr Whitfield says this typically makes the engine slightly harder to start but there is no change in octane.
Lachlan Riddel, proprietor of Gold Coast based tuning company ChipTorque, frequently dyno tests cars which have not previously been driven for several weeks.
“On the fuel mix we have in Queensland, I think fuel in a car’s tank is starting to go off in around three weeks,” Mr Riddel says. “We can tune a car, put it away for three of four weeks, come back to it and it will be either closer to detonation or less likely to make the same power.
“I think local fuel is brewed to reduce evaporative emissions in warm weather and, maybe because of that, fuel really goes crappy in eight to ten weeks. By that stage, the fuel is extremely prone to detonation.”
Interestingly, Mr Riddel hasn’t noticed the engine becoming harder to start but the effect on octane is pronounced.
Similarly, the General Manager of Melbourne’s Advanced Vehicle Operations, Steve Coates, believes fuel tends to go off in a car’s fuel tank quite quickly once it’s a couple of weeks old.
“After a couple of weeks not driving a car, I find that it will be closer to detonation than it was at the time of tuning on the chassis dyno,” he says.
“And the brand of fuel seems to make a difference as well – I find that Mobil and BP products are probably the best after being stored but Shell Optimax is really good when it’s new."
Clearly, there are some important factors to keep in mind when storing fuel in a container for several months or when parking your car for a few weeks.
Our recommendation is not to run the engine at high load with fuel that’s been in the tank for any more than three of four weeks and it’s a good idea to add at least 25 percent fresh fuel to the tank every few weeks. This will help ensure there are no fuel-related driveability problems or detonation and will reduce the chance of lacquer building up inside the tank."
Agreed, some interesting views. Problem is Lord Knows how secure the tank is so who knows if that was the cause.
The one thing i can say is the plugs are new so it is not carbon deposits on those.
The tank of BP on 1/2 tank of the old fuel has improved things but not cured entirely.
Is it worth looking at the fuel filter for "crap" in it?
Cheers
The one thing i can say is the plugs are new so it is not carbon deposits on those.
The tank of BP on 1/2 tank of the old fuel has improved things but not cured entirely.
Is it worth looking at the fuel filter for "crap" in it?
Cheers
Scooby P1 said:
Agreed, some interesting views. Problem is Lord Knows how secure the tank is so who knows if that was the cause.
The one thing i can say is the plugs are new so it is not carbon deposits on those.
The tank of BP on 1/2 tank of the old fuel has improved things but not cured entirely.
Is it worth looking at the fuel filter for "crap" in it?
Cheers
Yes - definitely. But remember, you won't be able to see the crap in the filter because it will be on the inside. Just change it.The one thing i can say is the plugs are new so it is not carbon deposits on those.
The tank of BP on 1/2 tank of the old fuel has improved things but not cured entirely.
Is it worth looking at the fuel filter for "crap" in it?
Cheers
RobP said:
Yes - definitely. But remember, you won't be able to see the crap in the filter because it will be on the inside. Just change it.
I can see that being a recipe for "checked teh filter and it was OK - still can't explain it". Better to reverse teh flow through the filter? At least then you could see whether it was crapped up.Regards
Paul C
paulcundy said:
I can see that being a recipe for "checked teh filter and it was OK - still can't explain it". Better to reverse teh flow through the filter? At least then you could see whether it was crapped up.
Regards
Paul C
No, my recommendation is to change the filter, not 'check' it. If you want, you can always pull the old filter apart afterwards to see what's on the inside.Regards
Paul C
My mate has been in touch with Yellowshed so it might be over to him - he comes very highly recommended on PH - to see if he can solve this bizarre issue.
Question to everyone though, are Nobles in the main reliable? If you go for a 600mile weekend trip etc are you always worried like you might be with a TVR that you'll be coming home on a truck?
Question to everyone though, are Nobles in the main reliable? If you go for a 600mile weekend trip etc are you always worried like you might be with a TVR that you'll be coming home on a truck?
Scooby P1 said:
My mate has been in touch with Yellowshed so it might be over to him - he comes very highly recommended on PH - to see if he can solve this bizarre issue.
Question to everyone though, are Nobles in the main reliable? If you go for a 600mile weekend trip etc are you always worried like you might be with a TVR that you'll be coming home on a truck?
Yes, in the main Nobles are fine. Many on here use as daily drives and many do continental trips with no issues. Still, Euro breakdown cover is always advisable if heading across the water (with any car).Question to everyone though, are Nobles in the main reliable? If you go for a 600mile weekend trip etc are you always worried like you might be with a TVR that you'll be coming home on a truck?
Scooby P1 said:
If the Noble is not used for 6 months?
My mate's 2.5 GTO has a "flat spot" around 5,000 rpm which Mole Valley believed was the ECU which was then replaced but the problem remained.
Yesterday he filled with some BP Ultimate and the flat spot has improved but not gone. Any suggestions and does this sound like a fuel problem?
L
Can you drive through the flat spot - in otherwords will the engine rev up to limiter after a hesitation or does it just refuse to rev above 5000 rpm? If it can rev higher then presumably the engine will then use more fuel which to my naive thinking would rule out a blocked filter as the total cause - although that may well be a factor.My mate's 2.5 GTO has a "flat spot" around 5,000 rpm which Mole Valley believed was the ECU which was then replaced but the problem remained.
Yesterday he filled with some BP Ultimate and the flat spot has improved but not gone. Any suggestions and does this sound like a fuel problem?
L
BobE said:
Can you drive through the flat spot - in otherwords will the engine rev up to limiter after a hesitation or does it just refuse to rev above 5000 rpm? If it can rev higher then presumably the engine will then use more fuel which to my naive thinking would rule out a blocked filter as the total cause - although that may well be a factor.
Yes Bob it does get through the 5,000 flat spot. It really feels like a bit of a "cough" like something is choking it and then it recovers. Almost like it's not firing on all cylinders for a second or two then recovers.Just gets more bizzare, it definitely feels like it is being starved of something briefly.
Maybe draining the fuel tank and starting with a fresh tank of Shell optimax might be a good idea?
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