Petrol Tank Sucks

[Mikesone]

Hi
Just thinking about the rush of air noise that you get when stop at the petrol station to fill up.

When you remove the petrol cap the air rushes in to the tank, which leads me to think that this low pressure in the tank means the fuel pump works harder than if the tank was at atmospheric pressure.

So, when I last filled up I did not do the petrol cap up completely, so air could get in and so no low pressure build up in the tank.

I felt the car ran better, certainly faster pickup, be interested if anyone else has tried this and if you thought it made any difference.

I'm running boost at about 12psi with a standard fuel pump.

thanks

[bradc]

Interesting point, I've always heard the sucking noise too, but never paid any attention to it. I wonder if a small breather hole would be worth while

[Kieran]

Interesting. I guess it's a sealed system to cut down VOC emissions to the atmosphere, but yes, I wondered what would replace the petrol when it's being sucked out.

[peter thomson]

I left the cap of once on an old metro turbo to check on a similar problem with the tank being pressurised which was causing the engine to be starved of fuel. Unfortunatly on a tight corner some petrol spilled onto a rear tyre and spun me off the road and down a bank though the car was running great and proved the point.Just a pity I ended up with it written off.

[thecustomer]

I left the cap of once on an old metro turbo to check on a similar problem with the tank being pressurised which was causing the engine to be starved of fuel. Unfortunatly on a tight corner some petrol spilled onto a rear tyre and spun me off the road and down a bank though the car was running great and proved the point.Just a pity I ended up with it written off.


ah, the fine scots spirit of enquiry is alive & well... now you see how we scots came to invent so many things... and with testing techniques like Peter's, why we also need fine drink to cope with our scientific investigations.

/pan

Will
26 years missionary work amongst the southern heathens

[g6acb]

runs of to check /googleit here - 'cause I always thought that petrol tanks in Fuel injected cars were meant to run as sealed units to pressurise the fuel to help it get to the pump......

?????

[Paul Beazer]

How could a vauum in the fuel tank possibly help the fuel get into the engine better? As others have said it would prevent, not help the fuel get in to the engine. When you're drinking a bottle of beer, you find it a lot easier getting the beer out by letting air in as you swallow, you dont just suck it out do you?
Same principle, mmmm schweet beeeeeerrr.

[Wodjno]

It may not help the Fuel get to the Pump and the engine :thinking:

But the fuel return if i am right in thinking, needs the vacuum of the tank to help it return to the tank :inquisiti

Flame me if i'm wrong :pimp2:

[bradc]

I think you might be right there wodj

[djb160]

But pauls contextual description was top notch either way.

[Paul Beazer]

Why would i wish to return beer to the bottle? /pan

[KHK]

Interesting point, I've always heard the sucking noise too, but never paid any attention to it. I wonder if a small breather hole would be worth while

i tend to think that the fuel pump/fuel line may have some little problem

My experience in the past was , once a fuel pump was changed, the noise disappeared.

[bradc]

Paul, think of a yard glass, wouldn't you prefer it if there was a return line so that you didn't spill half of it down your shirt and could drink it when you've had a few more seconds?

KHK, you might be right, I don't really know!

[psbarham]

i tested this a while back with a rizzla (really scientific :inquisiti ) and the tank is acctually pressurised , it blew the rizzla away from the cap , how its pressurised i don't know ,/pan before you ask

[Wodjno]

how its pressurised i don't know ,/pan before you ask

GAS VAPOUR..

[psbarham]

GAS VAPOUR..
i knew that , i was just testing to see if you were paying attention :inquisiti

[Wodjno]

Not exactly on subject ! But interesting all the same :pimp2: