Howdy
A couple easy things to try....run a line bypassing the secondary filter directly to the primary. So your line will go from the LP to filter to IP.
How much soft line is in place before the LP?
Can you run your feed line to the LP from a separate source, like the boat tank or motorcycle tank? It this works it will get you to the yard.
I am wondering if you have allot of soft line before the LP if it is sucking it down enough to restrict fuel flow.