I saw this thread when it was 1st posted.. but I didn't have a definitive answer.. still don't..
UNLESS theres a blockage in the tank any "normal" problem wont wait an hour to show up..
There IS a mesh filter screen under the inlet nut, but it will usually show its ugly head within minutes/seconds of operation, if its clogged..
NOT an hour..
IF your going to check it, you HAVE TO remove the big spring under the nut and HOLD DOWN the guts w/ a small screwdriver and using a 90* scribe or pick, fish out the plastic filter along the outside of the guts..
Dirty filters, bad lift pump, floaters in the tank, clogged inlet/return line, unvented fuel tank cap..
Some of these units have a filter screen in the shut-off tap coming out of the fuel tank.. you could siphon out the fuel or pull the line and unscrew it from the tank and see..
Does the inj. pump have a pull cable shut down or electric? IF its a pull cable, I've seen them vibrate to the shut-off position if theres no spring on it.. Normally on Fords theres a helper spring that connects to the small hole on the shut off lever that runs to the throttle lever, to keep tension on the sh-off lever to the run position until pulled..
Wish I could be more specific but it looks like this is a hunting expedition.