Check you have all the hoses and fittings tight. I have the 1200s, so I'm assuming it's basically the same. Mine will start gurgling a little when they're clogged up, or the intake strainer is clogged. I figure the fittings just being press fit start sucking a little from the suction due to a clogged intake strainer. But, I'd also suggest pulling it apart again and make sure you reassembled it right.