packrob

Before the pro restoration the fuel system worked just fine. I had an electric fuel pump installed as an auxiliary (separate fuel line). When operating on the mechanical fuel pump alone, the fuel filter bowl is almost empty and at speed the engine starves until the electric pump is engaged. When electric FP is engaged the bowl if full. I had the mechanical pump rebuilt by Terrill so I am confident it is working properly but I have not checked the pressure. Any ideas why the engine starves when using the mechanical pump only?