pg_dump on older version of postgres eating huge amounts of memory

I'm in a bit of a bad spot.  We have a number of remotely deployed
postgres servers.  We are very happy with the depenability of postgres,
but have recently run into a problem with pg_dump in SOME of the servers.

When doing a pg_dump databasename > file.dmp pg_dump eats up all the
memory, and is eventually killed because it takes
up a huge amount of memory.  The dump file is always 0 bytes.  It works
perfectly fine on our other server.

When we run pg_dump in verbose mode, it is trying to get the trigger
information.

Does anybody have any clue what could
be happening?  Or even how I can help determine the problem?  The machines
are only accessable to us by modem dialup.

Postgres Version 7.1.2 ( Yes, I know it's ancient - but again - these are
a number of servers remotely deployed... )
Redhat 7.1 ( see above ).

I know this is an old version of postgres, but I would really appreciate
any help I can get trying to track this down.

Steve