It's likely that the fuel tank is rusted and shedding particles into the
filter.  Did you save the old pump?  If so, look into the intake end.  It
may be clogged with rust particles that can be cleaned out and the pump
could be used as a backup.

On Fri, Jan 29, 2016 at 9:42 AM, Rick Cooper <rickdcooper@gmail.com> wrote:

> My fuel pump started buzzing some days ago so I replaced the pump and
> installed a second fuel filter between it and the tank, as a pre-filter.
> The buzzing went away for a few days but reappeared.  So I removed the pump
> again and attempted to clean it by adding input and output hoses, placing
> them in a pail of gas and running the pump.  I also replaced the pre-filter
> and noticed that there were rust particles in its inlet pipe.
>
> Again the buzzing went away and then returned after a few days.  I'm
> guessing this the pump is cavitating.  I noticed yesterday that immediately
> after I refilled the fuel tank, the buzzing was quite diminished though
> still audible.
>
> I'm thinking that the filter in the sump of the tank is clogged.  Could it
> be rusty?  The PO had parked this '87 Westy for a few years, following an
> auto transmission failure.  If that is the problem, what is the solution?
> Or is the cause of the buzzing noise possibly something else?
>
> Thanks, Rick
>