How do you have the pump mounted?
Is the noise "irregular" or a somewhat constant noise?
It could very well be normal - My pump was quite noisy even with a bunch of thick rubber washers thinggies - So I was like grrr! Then I was like WOAH! look at this huge chuck of foam that just popped out of thin air - so my pump is no longer screwed to the case, it's "positioned" by some zap-strap dealies and resting on a 1" thick chunk of foam - much less noise
