The only problem�I know of is if the purge valve sticks . This causes the engine to draw the vapors from the canister constantly . The purge valve is operated by engine vacuum: if this fails, the gas tank makes popping noises as the air gets sucked out of it, The engine can then run erratically, even stall , as the excessive gas tank vacuum inhibits the flow of gas. 
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Robert
1982 Westfalia

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