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.

Ranger Biodiesel Swap - Fuel System Installation

To improve accessibility and simplify mounting, I installed the new fuel system on the outside of the driver's-side frame rail. 

The small fuel/water separator is a Racor 110A from a marine supplier, which I bolted the frame directly ahead of the front leaf spring mount and plumbed to the sending unit with 3/8" fuel hose rated to SAE 30R14. 

(Note: use aluminum fittings for the fuel system wherever possible. Brass is reactive to higher biodiesel blends)

To connect the return line to the tank, I modified the stock 3/4" filler vent hose and installed a t-fitting. It now made from the 3/4" Ford Diesel fuel hose, as well as the following McMaster-Carr parts:

- P/N 5357K32 - (1X) Aluminum Barbed Fitting, Adapter for 1/4" Hose ID, 1/4 NPT Male 

- P/N 44705K452 - (1X) Aluminum Inline Tee Reducer, 1/2 x 1/4 NPT Female

- P/N 5357K44 - (2X) Aluminum Barbed Fitting, Adapter for 3/4" Hose ID, 1/2 NPT Male

The new fuel pump is a Facet 40107 12V electric pump, which I bolted to the frame below the driver's door and finished with 1/4" aluminum barbed fittings. The sending and return hoses are both 1/4" ID rubber hose rated to SAE 30R14, and I retained them with rubber-coated steel mounting clamps at regular intervals.

Finally, I wired the new pump to the extended leads for the original submerged tank pump, which allows me to turn it on at-will with the override switch I previously installed.

 

Ranger Biodiesel Swap - Fuel Tank Modifications

The original fuel pump, pressure regulator, and bypass hose are submerged inside the tank, and the fuel system only has a single hose to the injection system on the engine. 

The pump itself isn't rated for diesel or biodiesel, and I want to install a recirculating fuel system with an external pump and separate fuel return line to the tank, so it was necessary to dismantle the stock components and make modifications.

I started by removing the fuel pump and regulator assembly from the sending unit, and pulling the pump wires out of the bulkhead fitting. I sealed the holes in the bulkhead with marine epoxy, spliced the pump wires to a 6ft extension, and coiled them up for later use with an external pump.

I replaced the fuel pump and regulator with a custom pickup tube made from the following components:

- 3/8" ID SAE30R10 Submersible Fuel Line (6")

- McMaster-Carr P/N 5357K36 - 3/8" Barb x 1/4" MNPT Hose Fitting

- McMaster-Carr P/N 1610T14 - 6061 Aluminum 1-3/4" Dia, 3" Long

I turned the aluminum bar on a lathe to surface and chamfer the ends, then drilled a 3/8" through-hole and tapped to 1/4" NPT on one side.

The turned aluminum bar fits into the space vacated by the submerged pump, and is secured by the stock clamp. Once completed, I reinstalled the modified sending unit in the tank.