Re: Diesel fuel line installation
In my opinion, many of the home polishing systems are really pointless. Your engine's fuel pump is pulling fuel through your primary filter which is "polishing" your fuel. If you add a second loop to polish the fuel using another lift pump, you will essentially double your flow rate but with added complexity. To properly polish fuel you need high flow and high pressure which a normal lift pump is totally incapable of supporting. The professional polishing rigs actually flow enough fuel to clean out the corners of the tank, something that almost no home built polishing rig can do. The pros can also move around the fuel return to help get flow in hidden parts of the tank which you can't do with a normal sending unit.
Having a second electric lift pump in parallel with your fuel system that can be isolated is very helpful. When you need to bleed the system, you can use this pump. It is best if installed as close to the fuel tank as possible. In addition, it acts as a backup in case your engine lift pump fails.
Having multiple filters is good too. Putting them inline allows you to have different size ratings and filter efficiently. Personally, I really like the filter manifolds with 2 filters that allow you to choose which one is active so that you can actually change the other without shutting down. If you ever get junk in your fuel tank, having this setup is hugely helpful.