If there is a primer pump, usually a hand operated plunger one somewhere, use it.
If it won't start use a small electric pump around the gear pump on the engine to get fuel in everything, then reconnect the gear pump and give it a try. If you have some good batteries it should even prime it's self as is, or if it needs help you can get a can of fuel connected to the suction side of the primary filter (where the big fuel tank is connected) and hold it above the pump on the engine.
Good luck,
Grigg
