The 85 to early 88 Classic 900 is fitted with a fuel pump system featuring a duel pump design. The main pump feeds off of an internal bucket that sits in the tank. A smaller feeder pump fills this tank. This design allows the vehical to have a constent fuel level even when engaged in active driving.
Failures of this system tend to occure in the feeder pump. The filter to the feeder will fail allowing contamination to disable the feeder pump. In this case the filter and the mounting bracket for the feeder pump are the same item. Geneally this means if the filter fails it is a dealer only item. However with some cleaver Mcgyvering the filter and bracket can be sperated and an after market filter sock can be fitted.