Problem With Diesel Fuel Line

[gerry_wolff]

I am using biodiesel and have been advised to add an ancillary fuel filter with a clear case so that it is easy to see any dirt coming through the fuel line. This is because biodiesel is thicker than ordinary diesel and tends to pick up the dirt at the bottom of the fuel tank.

I have added the ancillary filter before the main filter and also a 'primer' to help pump the fuel through when changing or installing the filter. Although the car starts and runs OK, there are two problems:

* The bulb of the primer collapses.

* The ancillary filter becomes half filled with air.

The supplier of the primer says that the bulb should not collapse and suggests that there may be something preventing the fuel coming through from the tank as easily as it should. He suggests there may be some additional coubik filter in the tank and that this may have become partly blocked.

I would be grateful for any advice about this problem. Is there an extra filter in the tank and, if so, how can I clean it or remove it? Is there any way of preventing the ancillary filter becoming half filled with air? Is there a fuel pump and, if so, is it possible that this is not working properly?

With thanks.

Gerry