I agree and would suspect the fuel pump or its controller. BUT I expect your generator Control Switch has an indicator light that flashes a fault code. This may help your search. Section 4-1 in manual.
A. 2-blinks = low oil pressure fault.
B. 3-blinks = Service Fault, press stop once for second level code. This is a two digit code. First digit is 1-5 flashes a pause then second digit 1-9 flashes. ( 3 flashes then 6 flashes = code 36) (because if the initial 3 or 4 flash codes, to prevent confusion there is NOT a second level 33 or 44 code)
C. 4-blinks = cranking exceeded 30 second without starting.
Second Level codes =12 & 13 are controller faults, 14 & 15 governor, 27 output volts, 29 batt. volts, 32 cranking speed, 35 control card, 36 fuel - tank low, filters etc., 37 Config. fault.
Good luck with you diagnosis.
2012 Coachman Leprechaun 319DSF (E450) (32ft.)
2011 Chevrolet Equinox 4-cyl. AWD - towed
Souris River Canoe leTigre Quetico 17 - for fun