CRF450R Fuel Pump Problem
The fuel pump and filter fit into the bottom of the pump housing. The intention is to capture fuel in a small reservoir that prevents the fuel from sloshing around and ensure that only fuel and no air is pulled past the filter into the fuel pump. The problem is that the filter is positioned too close to the bottom of the fuel pump housing. It is so close that the fuel filter is pushed against the bottom of the housing which then jams the inlet tube inside the filter against the bottom of the housing. This prevents the inlet tube from drawing fuel from an open cavity fed from the entire filter. Instead the fuel must come through a very small portion of the filter right at the inlet tube. The many layers of filter material then tend to clog the small inlet tube opening..
You must move the fuel filter higher (up towards the electric pump) to prevent the filter inlet from touching the bottom of the housing. We also add some tie straps wrapped around the filter to force it into a round shape. This allows the filter material to pull away from the inlet tube. This ensures the filter inlet tube is centered between the filter layers and not jammed into them. This modification is so successful that it does not even require a new filter element, although you should purchase a new filter anyway. We can perform this modification for you if you send the pump in when we are servicing your suspension.
The fuel filter has multiple layers of filter material.