No fuel in the return? Then there's either insufficient volume delivered to build pressure in the line (leaning out the cylinders), or there's way too much pressure because the FPR is blocked. I vote for no. 1.

When the exhaust is lean, it smells acrid, eye burning stuff, due to the high NOx emissions caused by lean out. When it's rich, it has a gasoline smell.

Likely causes of lean out are fuel pump or pickup, water in the fuel (did you fill up after the wheeling trip at a non-high traffic gas station? - likely source of water in the fuel, as is deep water wheeling), fuel filter, fuel lines, low voltage to the injectors.