Twin walbros running in parallel full time is a ton way more fuel than is needed by those 230/80 injectors. For reliability I would keep them in parallel as that is a good setup but I would add in that you wire a multi-position switch inline between the pumps and the relay/s and mount it up in your cab .i.e a 4 way switch. Then you can have one pump on, one off, both on, or both off. Having both running when all you need for 80% nozzles is maybe 40 g/hr and you are running over double almost triple that at close to 120 g/hr on paper. You are also heating and aerating that fuel up much faster as well. Think when you only have a partial tank of the turn over rate. Say 10 gals being pumped @ 120gal/hr
I have not personally checked walbros but I do believe, based on tech info, they do not have check valves in the fittings so fuel likely can run back thru one creating a loop. If this is the case you just need to add a check valve to each output line and that will eliminate that issue. A way to know is does your fuel pressure drop fairly quickly when you turn off the engine? If so then they running back thru as the reg is restricting flow the other way.
