AP, I've had to do that with a long run of hose on the pump to get it (the pump) completely purged of air before re-connecting it to the long run.

Once I did that, the pump would pump water fast enough to push all the air out of the discharge hose (3" hose, 15,000gph pump)

www.hoosierpondpros.com

[Linked Image from lh6.ggpht.com]
http://www.pondboss.com/subscribe.asp?c=4
3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).