Piper Arrow electric fuel-pump

Anybody know how for long the electric fuel-pump
in a fuel-injected Piper-Arrow IV can be
operated for.?
indefinitely ? or intermitantly ?

The POH is somewhat vague as it says that the
electric pump can be turned-off in cruise and
I haven't spotted a limitation in the POH yet.

The reason I ask, is that I normally turn it off
when in mid climb, but on a recent long trek
I had some adrenalin surges when the engine
started getting rough.
The fuel-pressure was low and varying, hence
causing excessive leaning, thus rough running.
Turning on the electric pump got the fuel
pressure back to normal values and 'ops normal'

After some experimenting in-flight, I determined
that the the problem only happened when I was
using the right-tank, which implies that there's
some obstruction in that fuel line or in the
fuel selector.

So., any views on how long the electric fuel
pump can/should be run for ?