Beleaguered Grumman Corp. can look for continued bad news from Washington. Despite strong pressure from the New York congressional delegation, Defense Secretary Richard B. Cheney is standing firm in his plan to end production of Grumman's F-14 fighter. Instead, the Pentagon wants the Navy to buy a new version of McDonnell Douglas Corp.'s F/A-18. Long Island-based Grumman has already announced plans to trim its work force by 7% this year. Although New York members have won support for a plan to order the Navy to buy 12 new F-14s, Cheney has the clout to stop the move.