I was checking all vacuum hoses on left and right sides. On the left side, when I was following couple hoses down, I made this black unit (pictured in the center) touch the LHS thermostat housing (pictured on the left) and saw electric sparkles.

What is this thing? There are what appears to be fuel hoses connected to it (or passing through) on the back of it.

Whatever this is, it looks like it may be on its last legs...

 

Cannister purge valve. I think

This pic shows it on a Series III XJ6 but I'm pretty sure it was used on certain V12s as well


https://www.jaguarforums.com/forum/x.../#&gid=1&pid=3

Go to posting #10 in this ^^^ thread


Cheers
DD

 

Thanks, Doug. Yes, looks like this is purge control valve for the charcoal canister.

It was difficult to find a reference to it in the manual.

My guess is the wiring might be crumbling or disintegrating, that's why it sends sparks when touching t-stat housing. (No wonder -- it gets very hot in there)

 

This morning I managed to take a better picture of this purge control valve. See below.

The thing is when the body of the valve was touching the t-stat housing, there were electric sparks.

I tested with DVM and found out that it is getting 12V on the casing of the valve. Even with the ignition off and the key out.

Is it supposed to be like that? Why would it always be live, even with engine not running? That's strange.

How do I test it to find out if it is working as intended?




Purge control valve ('85 HE)

 

My 1987-older diagrams are no help as they show the valve but outright do not show where the wires go!

I'm sure that 12v to the case is not intended. I suspect a fault inside the valve.

I strongly suspect, but cannot confirm, that constant 12v is incorrect as well.

The valve is just a power-and-ground solenoid. It opens to allow accumulated fuel vapors to be evacuated from the cannister. I suspect it's tied-in to the 45-second timer so that it operates (allows evacuation) only on a cold engine.

FWIW, on the Series III XJ6 the valve is operated by an 'air switching module' which in turn is controlled by a coolant temperature switch the is closed when cold and opens at about 150ºF.

I'll do some more digging when I have time. Hopefully others will chime in.

Cheers
DD

 

If your regulations allow it, get rid of the entire fuel vapour purge fiasco from back to front!.

 

Greg,

In the Nevada county where my kitty lives, there are no requirements for periodic emission or smog tests.

When you say "get rid of the entire fuel vapor purge fiasco", what do you mean?

Remove the purge control valve from the line and let the hose connect directly to the charcoal canister? Or something else

 

The small bore steel breather line from the tank emerges just in front of the rear wheel on the LHS just inside the main chassis beam that runs over the rear axle. At this point it is connected to a rubber tube that runs forward to the space in the front of the LHS front wheel. You have to remove the baffle to see the canister in the space.
You can remove EVERYTHING from the rubber connector by the rear wheel forwards, the canister, the gizmos attached to the tubes from it in the engine bay, AND the tube that connects from it into the manifolds across the top of the engine. I have done this on a USA spec car. In effect, this makes the car to UK spec in this regard. leave the steel tube open at the rear wheel, and blank off any entries into the manifold, and any insulate off any loom connectors.
Greg