Fuel Filler Caps

Frank Mallory frankm at erols.com
Tue Feb 11 13:49:32 GMT 1997


Steve wrote:
> 
> Hi,
> 
> I normally just lurk on this list gleaning valuable information for the
> more knowledgable posters.
> 
> However, I have a question! I'm currently fitted a Ford Zetec with a
> custom fuel injection system to my Caterham 7. I've changed the fuel
> tank which now has a fuel pump mounted inside the tank feeding the
> engine via a high pressure hose. The existing fuel line is now used as a
> low pressure return.
> 
> The fuel filler cap normally used with fuel injected Caterhams is
> labelled as having a 'pressure release' facility. Is this absolutely
> necessary in a fuel injection system? Surely the pressure in the tank
> itself is no different to that in a carb based system? So the question
> is :- Can I use my existing fuel filler cap - which makes not mention of
> having pressure release?
> 

You need some kind of vent or pressure/vacuum release for your fuel
tank; otherwise, it may collapse from atmospheric pressure as the fuel
is used up (unless your tank contains some kind of collapsible fuel cell
or bladder).

If you have a separate vent, the type of fuel filler cap shouldn't
matter.





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