Originally Posted by teejayevans
Most probably an old Walbro 6xxx series, search for Walbro and FRB-13 which is a replacement.
I got a response from Yanmar North America. They directed me to Boatswain's Locker in Costa Mesa, CA. The service rep there was very helpful and actually spent a good bit of time looking through the old PacSea orders, which only went back to 1999.
After much looking, we figured out that it was a Walbro 2401 bellows style pump, which has since been discontinued. The closest thing is either a Walbro FR series reciprocating pump, the FRD-1 or the FRB-13 as Tom noted, both have USCG approval, the FRB-13 has the salt spray test approval in addition.
Stewart-Warner also has a 235A-D pump which fits the bill.