Gas filler flap replacment

[5l32v4c]

I took my gas tank out to get it cleaned (car has not been run for many years). In particular, the filler neck was pretty caked / corroded inside at the top. The metal sleeve that holds the spring-loaded flap (that gets pushed aside when you fuel up) was badly corroded and pretty-much fell apart, so I removed it completely.

The replacement cost for this little part is pretty high for what it is so I was wondering is it necessary to have it in there in the first place and, if it is, has anyone tried fitting one from a different make / model of vehicle.

My understanding is that this flap's (sole?) purpose in life is to make sure you don't put the wrong fuel in. With that in mind, the opening should be a standard / universal size.

[Mrmerlin]

the only person that will care is your emission inspection mechanic.
If you dont have emission inspections then you dont have to worry

[MPDano]

Are you talking about the small metal flap inside the filler tube? If so, this was designed to halt gas siphoning as far as I know. I guess it could be that regular gas had a larger diameter nozzle. Nothing to do with emissions visuals. At least in Calif and we have the strictest in the country.

If your talking about the fabric flap that cover the gas cap, that is more of a protection of the gas nozzle from chipping your porsche paint. Mine says something like check oil or something like that on the flap.

[honerboys]

regular gas nozzles were of a larger diameter than unleaded and the restrictor kept people from putting regular in unleaded cars - checking that this restrictor was in place used to be an emission item here in Colorado - but mine is missing and it wasn't checked so the car passed - i'm thinking that since regular gas is (as far as I know) extinct that this is no longer an issue - so I would leave it off - they used to sell replacement generic restrictors at parts stores - probably could still find one if you want

[5l32v4c]

I heard that one other potential purpose for this flap is to help create back-pressure when fueling-up so the cut-off trips when the tank is near full. Just need to be a bit more careful when filling-up, I guess.

I seem to recall that gas pumps in the US have a better sealing "boot" around the nozzle than we have here in Canada, so enough back-pressure might be created anyway.

[honerboys]

mine is missing and the pump shut off trips fine

[Plexus928]

I seem to recall that gas pumps in the US have a better sealing "boot" around the nozzle than we have here in Canada, so enough back-pressure might be created anyway.[/QUOTE]

I think the seal is to stop/restrict fumes from the unleaded fuel getting into the atmosphere.
The chemicals in it are reported to be more deadly (carcinogenic) than the lead it replaced.
that's progress for you.

[Reanimotion]

the flap has no technical function other than to stop an accidental fill of regular instead of unleaded

[Plexus928]

in Australia , on the phasing out of leaded fuel all new cars had to have a narrowed down filler, with flap inside , all the unleaded pumps had a very narrow filler nozzle to fit, in the transition period leaded fuel pumps had a bigger filler nozzle that could not fit into the narrow throat. This was to stop people using leaded fuel in new cars.(lead killed the cat anyway, so any performance gain was going to cost them big in the long run.)
I believe some European countries -as well as a flap/valve in the tank neck- have a seal on the pump nozzle that recovers carcinogenic vapours that might escape when filling. Starting to see a few of these appearing here.
I'm probably doomed, as I have a 1982, I get to do a bit of petrol sniffing when I'm filling. only seal at anytime is the cap, don't even really need a fuel gauge - check the level by just taking off the cap and looking down the hole. Get yourself a tank from an early model breath deep and die like a man.