Fuel Line Routing

[btmurph]

Hello the board!

I'm converting my 1970 C-10 p/u to a 6.2L N/A and I've got a couple of questions (or 20)...

I scored a dual fuel filter set-up off a 72 C-30 several years ago at a pick-n-pull. Looks like a conversion set-up out of a C-60 or something and is a primary filter and a separate secondary filter (I lucked out and the fram filters were still in place so I actually have SOME idea of routing and such).

1. should I put the primary filter before the lift pump and secondary after? both before?
2. are Napa filters good quality? I'm thinking the dual filter set 3123, 3124 (I think those are the numbers) with the water separator in the primary. I wish I could afford a Racor setup but no $$$!!!
3. there is no factory return line to the gas tank and as I can't afford a new tank plumbing one to the tank is, I think, impossible (without the bomb squad getup anyway). can I route the return line to before the primary filter instead? other possibilities? will the primary filter act as an air trap (there is a bleeder on the mount)?

Thanks ahead of time!

Brian

[DmaxMaverick]

Welcome aboard!

Fuel line routing should be:
Tank ==> primary filter ==> lift pump ==> secondary filter ==> injection pump (and injectors) ==> tank. You should have the water separator at the primary. Also, if you plan on operation in cold climate, both fuel filters should be heated, and use a good anti-gel additive.

Routing the return back to the supply line would be functional, but it REALLY needs to go back to the tank. If not, fuel heat will be excessive, and will kill several system components, including the injection pump. The tank (and fuel contained) is a heat sink to help remove heat from the returned fuel. This is a very important feature designed into the system. The return line does not have to be anything special. You can return it to the fuel filler pipe or tank, as long as the fuel gets back to the tank. If you return to the filler pipe, be sure to either have it low enough, or baffled, to prevent fuel from splashing against the cap or filler opening. Tank venting can force fuel out the cap vent (messy, and will screw up proper venting). Also, be sure to use a DIESEL FUEL ONLY fuel filler cap. The gasser caps don't vent properly.

Napa filters are fine, and probably one of the best (mostly rebranded Wix). Remember, "Friends don't let friends use Fram"!

[btmurph]

my tank is in the cab and while it does have a vent tube (from main tank body to top of filler neck) I think it's all steel as well (I'll check to be sure, I'm at work now tho). maybe I could use a compact tubing cutter to tee in and not blow up :eek:

as far as a cap goes, I have one of the old style (1/4 turn from open to close) cap setups and I currently have a push in vented locking cap, I've never seen that style in diesel but I haven't looked either :). probably the only good thing about my current tank is it's an old neck that doesn't have the unleaded only block-off plate

[DmaxMaverick]

Seat back tank? Even easier. Choose a location with some room around it, and drill a hole. Either weld (remove and purge, first...it's easy) or use a 90° threaded bulkhead fitting for the return. You will have to address the vent, though. Perhaps running a vent tube to the frame with some sort of filter on the end?? Check the venting to be sure it is very light, in and out.