No experience with Walbro, but two tips from dealing with Facet pumps. First, the inlet wants to be below the outlet. Install them upside down and they won't work - haven't tried them on the side. Second, they rely on fuel flow for cooling. Shut down the outlet flow and they'll overheat, drive off volatiles from the fuel, and vapor lock. You should be able the keep your hand on the pump - ie: less than 140 F.