fuel issue...NEED HELP QUICKLY!!

I'm more familiar with the Ford E-Series under Class C coaches. That said, the first couple years those units had fuel injection, it was Throttle Body (TBI) and they used two fuel pumps. One was in the tank and provided low pressure fuel to a high pressure pump located on the driver side frame rail. Did your mechanic check both pumps? The earlier in-tank electric pumps, used with carburetors, provided just a few pounds pressure. I don't know what the spec for the ones feeding the frame-mounted pump. Where was the filter he replaced? The on-frame unit I saw (1984 T-Bird TBI) had the pump and a filter on the same bracket. I don't remember if there was a second filter elsewhere.
Your gas tank needs to be roughly 1/4 full to fuel the generator. That's all the farther down the pickup reaches. That's so you can't run yourself dry with the genset and not be able to motor out.