The IP needs to drip when the fuel is under pressure. The "drip" that occurs at the "end of the stream" is not what you are looking for.

Think of it like it was a water faucet. If you turn a faucet off after it was running, it is going to drip for a bit. That's a different kind of drip that occurs when the faucet is not completely turned off. You want the continuous drip under pressure that happens when the IP is almost "turned off."