Gas cap-sealing or not?

[Jan-78FJ40]

Is the gas cap in a minitruck (81-22r) supposed to seal or not? The one on mine was completely lose, so I added another layer of rubber under the seal, and now it seals tight. However, not it sometimes almost dies at idle.
Diesel engines are so much easier to understand

thanks,
Jan

 

[2ndGenToyotaFan]

I think they should seal, but have a small vent hole in them.... Otherwise the vacuum would go way up as you used fuel and eventually the pump would not be able to get anymore gas....

 

[Jan-78FJ40]

I think they should seal, but have a small vent hole in them.... Otherwise the vacuum would go way up as you used fuel and eventually the pump would not be able to get anymore gas....

Thanks, that's what I though. maybe that's the problem and the vent hole is clogged.
cheers,
Jan

 

[Tools R Us]

IIRC fuel evaporative emissions systems were mandated in '71? If later than that and a US spec rig, the cap should be sealed and be vented through a carbon canister. Best bet is to buy a new cap.

 

[2ndGenToyotaFan]

That's why I said "I think" Hehehe