Are you running a return line? It might be too small causing the FPR to not be able to control fuel pressure right. Maybe you have the system plumbed wrong. BTW from what I've heard, the walbro is more of a pusher then a puller pump, it should really be by the tank.
Also, if there's fuel dripping out the exhaust, wouldn't your engine be hydrolocked from having a liquid in the combustion chamber? Any pictures of your fuel setup?