Fuel tank pressure
Discussion
Went to fill up with fuel yesterday and couldn't get the damn filler cap off 
The problem seems to be the amount of pressure that builds up in the fuel tank ( especially in hot weather ) just locks it on solid. Eventually got it off but the amount of pressure released was unbelievable. Does everyone else suffer from this ie is it normal ? Should there be any kind of pressure release mechanism ? I think my 335 had this a bit, but never experienced on any other vehicle.
Frostie
The problem seems to be the amount of pressure that builds up in the fuel tank ( especially in hot weather ) just locks it on solid. Eventually got it off but the amount of pressure released was unbelievable. Does everyone else suffer from this ie is it normal ? Should there be any kind of pressure release mechanism ? I think my 335 had this a bit, but never experienced on any other vehicle.
Frostie
I'm assumimg you've now got a 360?, and used to have a 355 not a 335...
Anyway, tank pressure is designed into the system, and is generated solely by heat from the engine bay. It should of course be a pressure and not a vacuum, as can be determined by the way the cap blows off into your hand, if you're quick enough to catch it.
There is a pressure relief valve, and you sometimes hear it humm when really hot and stationary, sometimes when you slam the door, it sets it off.
To help get the cap off in future, just smear a bit of grease or ideally vasoline onto the cap seal, and avoid filling the tank to the brim as this washes the grease off.
Modern fuels like Shell optimax and Mobil 8000 are really dry, and many seals in the fuel system can shrink back or dry up causing many different problems.
Not a common problem though...fuel caps seizing on a Ferrari.....it's a bit like the one about the bonnet hinges wearing out faster than the door hinges...
>> Edited by 360N-GT on Monday 16th June 13:36
Anyway, tank pressure is designed into the system, and is generated solely by heat from the engine bay. It should of course be a pressure and not a vacuum, as can be determined by the way the cap blows off into your hand, if you're quick enough to catch it.
There is a pressure relief valve, and you sometimes hear it humm when really hot and stationary, sometimes when you slam the door, it sets it off.
To help get the cap off in future, just smear a bit of grease or ideally vasoline onto the cap seal, and avoid filling the tank to the brim as this washes the grease off.
Modern fuels like Shell optimax and Mobil 8000 are really dry, and many seals in the fuel system can shrink back or dry up causing many different problems.
Not a common problem though...fuel caps seizing on a Ferrari.....it's a bit like the one about the bonnet hinges wearing out faster than the door hinges...
>> Edited by 360N-GT on Monday 16th June 13:36
360N-GT said: I'm assumimg you've now got a 360?, and used to have a 355 not a 335...
Anyway, tank pressure is designed into the system, and is generated solely by heat from the engine bay. It should of course be a pressure and not a vacuum, as can be determined by the way the cap blows off into your hand, if you're quick enough to catch it.
There is a pressure relief valve, and you sometimes hear it humm when really hot and stationary, sometimes when you slam the door, it sets it off.
To help get the cap off in future, just smear a bit of grease or ideally vasoline onto the cap seal, and avoid filling the tank to the brim as this washes the grease off.
Modern fuels like Shell optimax and Mobil 8000 are really dry, and many seals in the fuel system can shrink back or dry up causing many different problems.
Not a common problem though...fuel caps seizing on a Ferrari.....it's a bit like the one about the bonnet hinges wearing out faster than the door hinges...
>> Edited by 360N-GT on Monday 16th June 13:36
Thanks - I have a 550 ( no finger trouble this time
). Will try some vasoline around the seal. Frostie
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