It is possible that the modern fuel is evaporating out of the bowl, which would cause the pump not to function.
Do you have any hesitation when pulling away from a stop sign. Hesitation could indicate a defective pump.
When cold cranking, try this: crank the engine about 6~8 seconds. Stop cranking and pump the footfeed 3 or 4 times. Now pump the choke, and crank again. If the bowl is low of fuel, cranking for 6~8 seconds should fill the bowl, and allow the pump (if functional) to operate normally.
Jon.
