Was motoring along at 6.5 knots when all of a sudden rpms started dropping drastically. Thought at first the alt kicking in but it kept dropping and i thought i was going to lose it. It eventually levelled out but at much lower power setting. Then it would recover. Just for grins, i rebuilt this engine a few years ago and whole new fuel system including tank. Filters are all fresh. Has been workin for last few yrs.. The second time it happened, i noticed power was absent from the whole engine panel..i finally drop the hook and start to think how the hell could loss of electrical power could cause the loss of rpm on a basic diesel engine that has no requirement for electrical power. And then it hit me that i installed an electric lift pump tied to the key switch. OK, rpm loss i had figured out. Power that supplies the panel goes through a fuse block on the front of the engine and then to the panel. I pulled the fuse block off. The block is a plastic case that holds 5 fuses. If one blows. Disconnect load side and move to new terminal assuming problem fixed. The fuse that was being used was a bit weird as the plastic around the fuse wire was melted and some of the connectors were distorted. I went through the whole system and no signs of anything getting hot. So i move the wire terminal to a new fuse. The lugs were a little loose and dirty so i cleaned and crimped a bit. Started it up and it ran fine for rest of the week out. Fortunately, my fuel tank is only about a foot below the injector pump and i think the injector pump kept things going during the issue but a reduced power. Im thinking of running a dedicated 12v wire directly to the pump through an appropriate switch..key switch or other switch would power pump. Not both. Engines with electric lift pumps should have a backup plan in case of power failures...maybe the newer ones do...