25 HP Merc outboard, circa 1989, non-oil injected, with Walbro WMC carb (integral fuel pump), "external" reed block design.Engine runs fine if you keep pushing fuel to the carb via the priming bulb, but runs out of fuel otherwise.Here's what's been done so far:- complete fuel line replaced, including fittings and primer bulb; tank pickup and vent checked. Fuel filter checked -- clean and clear.- carb cleaned and carefully rebuilt, Merc rebuild kit, including fuel pump diaphram. Check valves look fine. No varnish or other crud observed.- Pulled reed block. All reeds undamaged, lightly seated against block. Replaced U-shaped reed block seal, which was pretty crudded up with what I guess was varnish. Replaced reed block-to-block, "carb adapter plate" and carb gaskets- Compression check: 120 psig in both cylinders- If I pull the fuel line between the filter and the pump, I feel no vacuum. I understand the pump should draw enough suction to pull fuel up two feet, so I should feel some suction, I surmise!Engine runs like a top -- trolled all day by squeezing the primer bulb every 1-2 minutes!- If I remove the carb, and blow on the air port at the downstream flange end of the carb, which provides the pressure pulses to move the pump diaphram, I can hear the diaphram doing its thing.Seems to me that the pressure in the intake cavity between the reed block and carb is not fluctuating like it needs to, but I'm stumped as to why. Book says reeds shouldn't be seated on reed plate, but stood off up no more than .007". Mine are just touching. Also, there are two small vacuum-like hoses that come off the bottom of the "carb adapter plate". Wondering if these might be players, though I think I read that these are just for cycling unvaporized fuel back into the cylinders.This has me stumped, but I think Ancient Mariner and others may have some ideas. I'd be grateful for any advice/experience. I'm sure someone out there has been through this before!