What has been your fuel system maintenance routine? When is last time fuel filters were serviced/changed?
As "North Main" suggested work your way from source towards injection pump.
0. Is fuel cap vent set to open position and does it allow passage of air? If not sure, leave it off or not tightened down all the way to test to see if that makes any difference.
1. What does fuel and inside of tank look like? Take out the fuel filler assembly/screen in tank and look at fuel and metal inside. Is fuel cloudy stale or clear-ish? Any rust in tank? If rust or gunky fuel, you should pull the draw tube out and determine if its plugged. Regardless while you have it out clean with Acetone or carb cleaner or similar. While your focused on fuel tank and if you are, or plan on using an auxiliary fuel source, you also want to pull the auxiliary fuel level switch and clean it. The aux switch can easily get gummed up and stick. You most certainly don't want it to stick in the bottom most position as it can over fill your day tank. For that matter, you don't want it to get stuck in any position if you have an Aux fuel source and expect to be able to refill Day Tank automatically.
2. Can you blow through or blow out fuel line to 1st pump to insure its open? Same with all fuel lines.
3. When is last time you took bottoms off fuel pumps and cleaned or replaced screens in bottom of pumps? Be sure to remove magnets off the bottom pump caps and clean off any metallic particles and replace once cleaned.
4. Working your way through all the filters, should you still have no fuel coming out of last fuel filter then its time to remove check valve and soak in Acetone or similar. Also, be sure to open brass purge plug on top of last fuel filter and bleed out any air once you get fuel to that point.