Some basic things to check:

Did you prime the suction strainer?

Are you running the pump on high?

Did you open the release valve on the filter until water comes out?

Is the skimmer filled with water?

When doing any of the above follow the owner's manual for safety.

I believe the suction head is ok, but you should install a check valve in the vertical suction line to help maintaining the prime for re-starts.

Dave