Gryphon313
Full Access Member
When the canister purge valve is sticking open, you get that hard start after fueling because adding fuel is venting fumes into your intake. The vent solenoid on the charcoal canister is normally open when the truck is not doing a vacuum check on the vent line and the charcoal canister can only do so much.
This unmetered air/fuel is not seen by the truck’s pcm so it has no way to compensate for it. Same thing occurs when your truck is at idle. Under throttle it’s less of a factor.
When it’s a really bad vacuum leak there’s a possibility of sucking up fuel through the purge lines under heavy throttle. There are even stories of some fuel tanks collapsing/imploding under the vacuum. Obviously, those are extreme cases, but it does point to the necessity of replacing a failed CPV.
This unmetered air/fuel is not seen by the truck’s pcm so it has no way to compensate for it. Same thing occurs when your truck is at idle. Under throttle it’s less of a factor.
When it’s a really bad vacuum leak there’s a possibility of sucking up fuel through the purge lines under heavy throttle. There are even stories of some fuel tanks collapsing/imploding under the vacuum. Obviously, those are extreme cases, but it does point to the necessity of replacing a failed CPV.
