I am using a glow plug style vegetable oil pre-heater unit on a Citroen Xantia with a Bosch pump. My fuel mix is 80 per cent new vegetable oil and 20 per cent diesel. It was fine at first, but now it stalls in the morning even as the engine gets hot. I then need to prime the engine/pump with the hand primer to get it started again. Once the engine is at normal operating temperature then I have no problems whatsoever. Surely if there is a blockage in the fuel strainer or injectors or anywhere, then the problem would be there at all times?