Hopefully I can shed some info I have learned. First off new member here!, so bear with me... Been creeping Jugernaut and Mercs posts for a bit now. I have parts sittin on my toolbox to do a fuel system to my 6.0 since my fuel pump just **** the bed.
The return on the 6.7 should be plumbed, there is a thermal recirculation valve that routes warm fuel back into supply to high pressure pump on the 6.7. If its just capped off yes the pump can "cavitate". How others have ran the pump with return bypassed is a mystery to me.
A new fuel pump does come with a filter inside of it.
Merc, why not just run quick connect fittings on the 6.7 pump? I found Dorman #800-111 (napa 7306720) is supply 1/2". Dorman #800-173 (napa 7305734) 12mm. That is the route I will be using, doing this will also allow someone to run the 6.7 secondary filter and buy just the 6.7 filter kit, which I am not doing. I will be running a w/s before the pump that will include a drain and WIF sensor and 3 micron similar to the cat post pump.
Now, with the dummy filters. A person can make a dummy filter for the 6.7 pump. Not as easily as the 6.4/6.0, where you shim the end of the cap with some pvc from what I have read. With my 6.7 pump apart there is a valve in the inlet hole that is opened when filter is installed. I stripped the filter media off the filter and its just plastic and flimsy, I don't recommend making a dummy out of this. Much rather a guy fab something up using aluminum or stronger design, use your imagination.
Here is the valve.
Here is the thermal recirc valve which doubles as relief valve say pump hits it's max rating of 120psi.
Heres the route I went being I'm running a remote w/s before the pump for ease of filter changes.
I just removed it! Found a "cap" at local hardware store, actually brought pump with me and grabbed a bunch of different options but thats what I ended up using. Used JB kwik weld as its resistant to shop supplies, fuel, oil etc. Used a 1/4" die grinder to clean hole out, and had to take some material off the cap so it didnt obstruct the inlet hole. Than applied JB around the hole and around the cap. Inserted and ran some more JB around cap. Let dry. Sanded cured JB and apply another big layer of JB around the hole thing. This port is not pressurized so it should be fine. I am doing this so I dont have to run a 6.7 filter. I will also be installing a shut off valve between Beans sump and first filter header.
I will be creating a thread for my install, just waiting on a few more things to arrive and time to do it. My setup will include sump -(possible 6.4 pump as volume lift pump) - remote header with w/s -6.7 pump - remote header with 3 micron - custom reg return feeding back of heads - aeromotive regulator out front - return back to tank routed through pump to a bulkhead
Big thanks to Merc and Juger for inspiring this to me.