- - Here is the simple system I use utilizing a Walbro UL listed diesel fuel pump. There is only one model Walbro but it comes in 12VDC and 24VDC flavors.
- - The level of the fuel tank does not make any difference in the system. Normal diesel fuel systems operate by an engine mounted "lift pump" that sucks fuel from the main tank through the Racor filter and then supplies it to the engine systems. The engine "lift pump" can suck fuel from a tank well below the level of the engine or above the engine.
- - The idea is to maintain the original fuel path from tank to engine. So the first "Tee" is put into the fuel line exiting the Racor filter on its way to the engine lift
pump. Downstream of the "Tee" is the ball valve. This ball valve shuts off the flow directly to the engine and now the "lift pump is sucking fuel from the tank through the Racor and now also through the Walbro pump.
- - The fuel line exiting the Walbro has a Tee installed with a ball valve on each leg of the tee. One leg of the tee connects back into the fuel line going to the engine lift
pump. This is like an alternate routing for the fuel and should the engine mounted lift pump fail, the Walbro can now replace it and pump fuel to the engine systems. Additionally this alternate path with the Walbro turned on will allow you to "bleed" the engine fuel system of air without having to crank the engine.
- - The second leg of the tee downstream of the Walbro connects to a "tee" in the return line from the engine back to the fuel tank. By closing both ball valves that direct fuel to the engine life pump and opening the ball valve to the return line you now have a recirculation system of fuel from the tank to the filter and back to the tank. Additionally this loop back to the tank allows you to open the Racor fuel filter
, change the cartridge, close the Racor and then activate the Walbro pump to suck all the air out of the Racor fuel filter
- - There is only one size Walbro fuel pump but it comes in 12VDC or 24 VDC models. The Walbro runs my 140 hp 6 cylinder engine fine and will recirculate (polish) the diesel fuel in my 300 gal fuel tank.
- - To recap the minimal system needs one Walbro Pump; 3 - Tee's and 3- ball valves. Plus wiring
, fuse/cb; and switch for the Walbro.
- - For duel tank systems (day tank and main tank) there is normally a selector valve before the Racor fuel filter that allows fuel on one tank or the other to enter the Racor Filter. You would normally only be concerned with polishing the fuel in the main tank when is then fed into the day tank. But with additional valves and tees you could also polish fuel in the day tank.
- - Water separation is normally done within the Racor 500 or bigger filter system or my a separate water filter both of which are "upstream" from the Walbro.
- - The system I described allows the Walbro to do the following: polish fuel; replace the engine lift pump; supply fuel pressure to bleed the engine fuel system; and bleed air out of the Racor filter after changing a fuel filter.