Evap canister electric purge valve- Evap rehab

Hello all- I’m back. Starting a new thread because I’m going to rehab my Evap system. How do I replace this part- I can’t seam to find it anywhere online. I know Ford used similar but can’t find exact match:
Part number:DAC-2617

Isn’t it just a simple NC electric valve?

Ok my friend who has an XJ6 gave me the part number that fits easy:
Rock Auto has it for like $37.

1. STANDARD MOTOR PRODUCTS
Vapor Canister Purge Valve Connector
Part number: S566


and
2. STANDARD MOTOR PRODUCTS
Vapor Canister Purge Valve / Solenoid
Part Number: CP403

The nipples look to be a bit small but you can probably work around that one way or the other.

I presume you’ve confirmed the original is inoperative. Is it mechanically stuck or electrically dead? If the former, I wonder if a slathering of carb cleaner spray or similar would revive it?

Cheers
DD

1 Like

My friend said it was a perfect fit but will ask. I didn’t bother with testing. It’s such an inexpensive part- why the heck not just change it:) I’ll keep the original in a box of course. Lol

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If you want to rehab your Evap system, Jeffrey; it would be more relevant to change the charcoal canister - or the charcoal within it…

It’s a regular service item; the charcoal deteriorates over time, losing it’s necessary properties. Which also happens if it is exposed to liquid fuel. Besides, it may solidify and block the ambient air intake - feeding manifold vacuum to the tank (worst case).

The purge valve simply closes the passage from the canister to the carbs with ign ‘off’ - to prevent fuel vapor venting to open air via the manifold. Which honestly seems a bit over the top…:slight_smile:

As an aside; on later cars the purge valve was entirely vacuum operated - opening the passage by manifold vacuum…

Frank
xj6 85 Sov Europe (UK/NZ)
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Done!- I tested the old one and it works so Im leaving the purge valve. I think you are right- its over the top. Charcoal canister is cleaned and tidy with new stuff.

No. It is normally open. 12VDC across the thermal switch at the rear of the water rail is applied to the purge valve, closing it until the engine is warm and the thermal switch opens and breaks the circuit to the purge valve. It is also a one-way valve meaning air flows in one direction and the valve is marked for proper orientation.

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Why should the valve be closed until the engine is warm, Claude? The purpose is to purge fuel from the charcoal in the canister by drawing ambient air through it - which happens whenever the engine is running. Engine temp has nothing to do with that?

On the other hand; electric operation may explain the mysterious ‘fourth’ sensor on the water rail discussed in another topic…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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Good info. One was clogged and caked with stuff. Both were inop when tested.

Not to mention the mysterious Air Switching Module.

In the S57 guide (presumably correct, but…) that temp switch is shown as normally closed, sending key-on voltage to the purge valve and the Air Switching Valve for the air injection system, more commonly known as a diverter valve…

Key-on voltage from the temp switch is also sent to the Air Switching Module which, near as I can tell, has nothing to do with air switching but, rather, seems to force open-loop running based on the temp switch or the throttle switch.

I’ve never fully understood the Air Switching Module. Too many diodes ! :slight_smile:

Cheers
DD

So question…what would be the effect if the valves were removed altogether?

I’ll need more coffee for that.

But lack of coffee doesn’t prevent me from wondering how many of the temp switches have become inoperative over the years…and what happens as a result, perhaps without the owner/driver realizing it.

More later

Cheers
DD

I’m guessing that keeping the purge valve closed during starting and warm up helps maintain that higher idle created by the air valve. I had the opportunity to bench test my original DAC2617 purge valve when it was working and can verify it was open when no power was applied. At some point my idle dropped during start up and I found the evap harness burned to a crisp near where it runs along the engine on the right side, and the purge valve dead shorted and in the open position. A long search for a replacement purge valve led me to this thread and thankfully, the normally open purge valve recommended by Jeffrey, above. I will have to report back next week as to whether the idle returns to normal (high) on cold engine startup after I replace the purge valve. I have read that some have eliminated the purge valve altogether, leaving the line open all the time. I think unmetered air through the purge valve to the manifold during start up may affect how well the engine starts and warms up since the computer is programmed to assume the valve is closed.

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As very little air flow is require to purge the canister, Claude - a restrictor ‘should’ be fitted in the purge valve/hose.

Earlier versions used the purge valve, later replaced by a plain hose connected to the crankcase ventilation pipe (with a restrictor). Later still; a vacuum operated purge valve was fitted - opening the valve when the engine was running…

In any case; the amount of unmeasured air involved is minimal - but when present on a hot engine; just countered by tweaking idle and mixture. When cold, during starting and warm-up the ‘false’ air is insignificant compared to other factors - and unlikely to cause starting problems…

However, it is sort of academic; if this is how your purge valve is working - so be it. The expected increase in idle should be around 30 - 50 rpms - no more, probably less. The delay in purging by waiting till the engine is warm is likely neither here nor there…:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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