After media scrutiny and watchdog complaints, former congressman William D. Delahunt has decided to help the town of Hull with an offshore energy project without taking $72,000 in pay from $1.7 million in federal earmarks he secured while still in the US House. The Quincy Democrat made the surprise announcement Thursday night, when he told Hull officials and members of the town-run Hull Municipal Light Plant that he would do the work he received under a no-bid contract for free.