What's your extra filtration and water separator setup like? Are you heating your WVO?
I don't believe in modern common rail emission controlled diesels and would never own one. Vane type Diesel pumps are too sensitive to fuel lubricity and viscosity for long term WVO use, IMO. The Mercedes piston type Diesel pump is superior for that, because the pump body is lubricated by engine oil instead of the fuel. The pistons are easy to change out.
Where I work they use Biodiesel. They have equipment that sits around for several years, and it gets gummed up. I got one of their old diesel mowers,, and have been trying to clean it out and get it running. I finally got it last summer and was able to mow all summer with it. But it sat over the winter and when I went to start it up the other day, the electric fuel pump was locked up again.
I have pulled the complete fuel tank out and cleaned it. I tried anyway. Whatever this sticky stuff is that comes out of the Bio, diesel doesn't touch it. Brake cleaner has a hard time with it. The only thing that seems to dissolve it is 911 in the red can.
This tractor has a suction filter in the tank, the electric fuel pump, then a separator filter, then a cartridge filter and then it enters the injection pump, and then it has a return to the tank. I added a second suction filter and when I went to start it this season, the filter I added was totally plugged(it's the glass see through type). I cleaned it out and thought it would go but no, the fuel pump was stuck and it burnt it up.