As posted by OP, Onan discontinued using the fuel filter at the carb. They offered a fitting to replace the filter. The replacement carburetors have a metal tube to connect the fuel line to carb. Onan considered this filter redundant, since they have a filter installed in fuel pump inlet under the base. And they were prone to leak, and Onan now has a much better filter p/n 149-2341-01, available to use at fuel pump inlet. I would not use the plastic in-line filter in gen compartment (imho)