RE: Quadra 52 won't run under 3500 HELP
Hey Jim,
Seems like you are on track to solve your problem. Talked to Dick at B&B Specialties and he told me your engine is on its way there. If Dick can't fix it no one can. BTW he runs one the most honest operation in the hobby and is a real gentleman to do business with.
He seems to agree with me that probably the pump diaphragm membrane may have hardened after such a prolonged time in storage. I'm sure Dick can easily overhaul your carb but if I were in your place I will consider upgrading to a Walbro that fits. Dick will be more knowledgeable than anyone to set you up with the correct model Walbro.
Good luck and happy flying.