ECM-430D small leak and the smoke test

[bg212]

How does the EVAP smoke test intend to work? Is the system supposed to be sealed?

I.e., I connect the smoke machine at #27 (at the purge solenoid hose towards rear).
I replaced leaking #6 (canister to purge shut-off valve).

Before that I had both major and minor EVAP leaks. Now I have only a small leak. Smoke now comes out of #19 (vapor canister filter, above the rear right wheel, right below filler neck) which has an opening (plastic neck) at the bottom.

If I plug that opening with my finger, the pressure builds up until it comes out of filler cap (which I am going to replace).

But, #19 that vapor canister filter is fully open: you can blow in or out, it's not a valve.

Now, if pressure relieved either out of filler cap or vapor canister filter, there is no way the negative pressure can be maintained in the tank (i.e. this is what small leak mean) as it will be immediately lost through the #19 filter.

Or does it indicate that shut-off valve #5 is bad and should normally be closed?

GR-337031.jpg (50.36 KiB) Viewed 134 times

[scot850]

#5 is the role over valve. It is I believe normally open unless the system is testing for leaks when it will close the valve electrically.

You can buy just a seal for the fuel filler cap and then recheck it. Also check the pipe seat around where the seal sits for damage. It is possible to damage the surface.

I would replace the cap first and then retest the car via the check engine light and see if it returns.

Neil