I’m not finding any Purge Control valve anywhere. Only vaccum tubes to to the cansister area, no wires (except for lights) and they all end on manifold vaccum connections. 3 small ones and one big one. So maybe it was removed before I got the car and that was originally part of the Purge valve wiring and was left unconnected.
Yeah, carbon canister system is all vacuum, no electrical – post-recall, anyway.
What about the air pump? It runs all the time, but there’s a valve that switches its output from exhaust tract to RH air filter housing. Is that valve vacuum or electrical? I don’t remember.
Pages 17-2 to 17-9 of the XJ-S ROM covers this Purge Control Valve in the Emissions Control section on “Canister purging” for the 1979-1984 MY cars. It is shown as component “W” in figure 11 on page 17-2. Neither of my 1990 V12 Jaguars has this Purge Control Valve but my Series III XJ6s do inside the engine bay nearby the carbon canister. There is a 45 second timer associated with it to prevent purging the carbon canister through vacuum until after the catalytic converters are “alight”.
Paul
The air pump diverter valve is vacuum controlled by a thermo valve at the rear of the right coolant rail. The purge signal goes through a similar-appearing thermo valve near the front of the left coolant rail. Perhaps the vacuum line is off of this thermo valve (located near the FFI temp sensor).