At 09:46 PM 2/13/2013, neil n wrote:
>I'll be curious to see if the pump noise ceases. But as you say, low
>flow rate on that return pipe so improving flow on it may not make any
>difference.

I thought you were joking about pump noise.  If the pump is
cavitating, it will be because of a problem on the inlet side.  If
the kinked line is causing noise it will show up right at the kink
(but I very much doubt it is with such a low flow rate).  Get out
your stethoscope and listen to it.

If the pump itself has worn to the point where it's noisy, letting it
pump kerosene through short hoses into and out of a quart can ought
to show that up.

Are you familiar with the cavitation noise?  A bit hard to describe,
but sort of a high-pitched buzzing/singing.  If God forbid the
bearings are chattering, it will scream in pain and have low output
and probably high draw (since the shaft is rolling around the inside
of the bearing instead of rotating in it).  Dreadful horrifying sound.

Is the pump resting on something that will transmit noise around the
rubber mounts?

Does pumping fuel from a coffee can via a short hose kill the
noise?  If so, look to the tank inlet filter or other obstruction in
the inlet line.

Yours,
David