Ranger Biodiesel Swap - Fuel System Revision

 I posted my original fuel system design on the "TDI Swap" facebook page, and one of the moderators pointed out a major flaw in my design. 

My 1.6 diesel engine is equipped with a Bosch VE Rotary Injection Pump, which were used on many mechanical diesel engines with varying horsepower ratings. The engine is only rated to 55hp, and its Bosch pump has the second-smallest 9mm piston for the injector. However, ALL of the VE pumps, from 8mm to 14mm and regardless of engine HP rating, used the exact same mechanical lift pump to circulate fuel between the tank and the pump housing. 

What this means, is that my Facet electric pump is severely undersized for the fuel demands of the mechanical Bosch pump! Rather than upgrade the electric pump to one with higher flow, I decided to install a pump bypass with check valve, and use the electric pump for startup priming instead of constant operation.

Before starting the engine, the electric pump can prime the entire fuel system. Once the engine starts, the Bosch mechanical lift pump will begin to draw fuel independently of the electric pump, eventually exceeding the feed rate, drawing more fuel than the electric pump can provide and creating a suction.

This suction will open the check valve in the bypass line, and begin drawing fuel directly from the tank without the electric pump's help. At this point, the Facet pump can be switched off, and the engine will run normally.

 I installed a t-fitting into both side of the Facet pump, and plumbed an 8mm check valve parallel to the pump body. The check valve is held in-place with a rubber-lined steel clamp, and the hoses are routed to avoid chafing on the parking brake cable.