Chances are that the screen on the pickup tube in the tank is clogged. If its been sitting for awhile the rust and scale in the bottom of the tank adds up. Also, have you changed your fuel filter(s)?
And its worth loosening the nut and dumping the collection bowl on the fuel pump. In fact, that's where I'd start. Recently one of the trucks on one of our off-road runs just stopped, for no apparent reason. After fiddling with filters, etc. with no luck, we removed and dumped out the sediment bowl. Put it back on clean, and away it went. Don't know quite why, but the removal appeared to allow some scum that was creating a blockage to wash its way out.
Clean the pickup screen and change the filter anyway!
Good Luck!
Dave
