Trying to pump pure veggie oil into Peugeot Boxer using old Bosch 15-60 130 Combi Boiler Pump but its not .?

Can hear it working, put an elbow fitting & 19mm plastic tube on the end that pumps out of the container & a straight fitting & 19mm plastic tube into vehicle tank. Ive primed it from oil in a jug & when nothing pumping through, opened the bleed screw in centre of pump, but still not pumping You can see air bubbles on a minor scale in the plastic pipeline,to show some kind of life but its not doing what i'd hoped for. Has anyone any experience of a similar quest.