I just replaced the fuel line on my Weed Eater BV1650. Now the carburetor won't prime fuel. I've tried "air-priming" it with the hoses off and on and that works, but as soon as I put the hose in fuel, it won't prime. (The bulb stays in when pressed and takes a long time to pop back out) It does this as long as there's fuel in the carb. Once the carb is dry again, it primes fine.