Is greasecar still looping the veg line? if they are looping it back on itself the only hope to clear the line is to alternate between veg and diesel every 4 or 5 seconds. This will purge the air to your diesel tank.

Alternatively, if you have the know-how I would recommend plumbing a return line for the veg right to the veg tank.

Re Biodiesel for cheap. Buy Methanol by the drum. It's as cheap as a dollar a gallon that way.

__________________
-----------------
1980 300D 300K KM - parting out
1979 300D 375K KM - parting out
2 300Ds for sale