To get to the fuel pump, drop the generator (exhaust off, 3 AC wires, 1 12V DC, fuel hose, and 1 snap connector, 5 bolts). Remove the top of the green box (4 torx heads, lift off).
The pump resides in the left rear corner, taking the service access door as 'front'. About $60 at the Onan dealer. Be wary; somehow they sold me an identical pump, except the outlet was facing the opposite direction and the bracket was about 3/4" too low. Compare carefully before installing.
Have fun! I sure did (ha!) ;)
Jim, "When the chips are down, the buffalo's empty!"