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Discussion Starter #1
My 2018 Silverado is throwing code P0446 which i causing a rough idle and lower power when accelerating. It is also impossible to add fuel to my tank. I can put in about 30 cents before it kicks off. It takes 10 minutes to get half a tank. I'm being told to change the canister purge valve. Anyone dealt with this before?
 

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could be canister , or could be fuel cap, plus a few more could be's , instead of throwing parts at it start testing and find the cause, throwing parts could get expensive
 

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Disconnect your vent hose at the canister and see if you have charcoal beads coming out of it. Do you "top off" your truck when filling?
 

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If you fill the fuel to the max in the tank, then the liquid gas will damage the canister .. when hot out the in ground gas cool expands then dumps the liquid into the canister .. breaks down the charcoal and the particles mess up the vent valve.. also some had cracks on the body of the canister...
 

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This also happens with a full tank when parked inside a heated garage. Fuel vapour expands and just like JCat said.... pushes fuel into the canister and causes problems.

Al
 

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Discussion Starter #6
This was the first time I’ve ever filled it up. Just purchased. Pre owned. Still under warranty so Dealership changed the canister and I was able to fill it up. Still idles a little rough so I’m just waiting for it to throw another code. This is also the first GM vehicle I have ever owned. Thanks for your help
 

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This was the first time I’ve ever filled it up. Just purchased. Pre owned. Still under warranty so Dealership changed the canister and I was able to fill it up. Still idles a little rough so I’m just waiting for it to throw another code. This is also the first GM vehicle I have ever owned. Thanks for your help
Glad we could help
 
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