BB-

I just did mine today.

Looped return. Let me explain.

return goes to a tee with a spring type check valve closest to tank side of tee.

ball valve on the other side going to a second tee.

second tee goes to suction side of lift pump. crude diagram below


inject pump-lift pump-----teee------selector----diesel filter---tank
^
ball valve
v
injector return--tee----check valve----return--selector-tank

this way the balll valve between the tee can be closed for air purging during a filter change and left open during normal running.

It works well looping most fuel as needed by the engine and surplus fuel pumped by the lift pump is returned to the tank of choice depending on the selector valve choice.

You must change the stock filter to suction side of selector valve to reduce change over time and cross contamination of fuels.

i will try to draw a diagram easy to understand and post it.

Mercedes love running veggy oil but it does make slightly less power but it burns cleaner than dino fuel.


Steve