I know this is very generic but remember to always check your return fuel line for clogs when diagnosing engine problems. I know its not a trawler but my john deere fork lift was not running correctly. After a lot of head scratching (I didn't get any fuel from the return) The return from the injector pump was clogged full of crap and it would make the engine stall like it was running out of fuel. Just remember to check your return line when figuring out whats wrong. Have a good day.
Paul
Paul