Hello everyone,
Would someone help with the following? :
How would the engine of a 1986 XJ6 Series 3 behave if all or any of the three vapour pipes are accidentally disconnected from its Carbon Canister CAC3814?
Vapour Pipes: CAC8900/11--CAC2641/1--CAC3889. Thank you.

 

you would smell fuel vapor, otherwise the engine would keep ticking.

 

Thank you for your response Jose. Obviously, I would smell fuel vapor. I wanted to know how would the engine behave if ...............! Would the engine be very hard to start,....... to fire?

 

not really, that would be a separate issue. I have one of my check valves defeated since 1991, so that fuel vapor does not build up pressure in the tanks and cause the expansion-contraction problem typical in these Series 3 cars. No issues starting the engine, zero, nada.

 

Tis a somewhat complex but workable system to reduce emisions into the atmosphere.


In earlier days, gas tanks were vented via the gas cap. No longer, now, they are supposed to seal. I have my doubts as to the sealing on mine. I do have new ones, but that is way down on the to do list.


Now, the vapor/vapour is "stored" in the charcoal filled canister. And, from time to time, the engine has a "purge' valve that opens and cleanses the canister.


Eventually, it will fall far behind and/or the charcoal degrades and it doesn't work. Change the cannister or merely the charcoal in it. Most cars went to the wrecker way before this.


As I understand it, the one way valve allows the vapor to flow from tank to cannister, but not back to the tank. Tis a tiny orifice anyway. So, piercing it changes little, Vapor flows, engine purges, it stays out of the atmosphere.


True, the engine gets a tad more fuel when the purge is cycled, but, lost in the whole mix of things.


Disconnect it and the tank vents to the atmosphere. And the engine purges the atmosphere!!!


Along with catalyctic converters, just doing good, with no engine harm.


Air pumps are another matter. But, for another day.


Carl