The tank we built was for the veggie oil and it has not even been used as yet, because the car will not run on the diesel fuel. I will have a kid make up a diagram to post so you guys can see the route for the fuel. We have 2 three way values to change from diesel after the veggie is heated. The pump was changed to pull the diesel through the diesel filter and then into to first value that would switch from diesel to veggie. It goes then through the pump into the injector assembly. The air must be getting into the diesel system somewhere before the pump. I had a owner of the same type of 300, running veggie and copied his route. He said to replace the stock pump, because it is usually not working well after all these years. We will take some pics and make the diagram asap. Thanks so much for the help.

Barney