Thanks, PEH and phantoms,

I've read the posts on the fuel strainer, but I didn't see anywhere the size socket wrench needed to remove the strainer on a Mercedes '84 SD300. I think it has to be a socket wrench owing to the small space I have to work where it comes out of the tank.

I am about to do the test you suggested to see how much fuel comes out of the line when it is taken off the strainer, but I am almost positive it is plugged with fungus, since I just replaced my filter and prefilter and still had power loss. I had used biobor a few weeks ago. It helped, but the problem came back. Added doses of biobor didn't help, but it may be because I refueled before adding the biobor and it didn't mix well. I am now trying to get my tank level down in case I need to empty it, so I don't want to put more fuel in again, so added doses of biobor don't seem to be helping because they may not be mixing.

In any case, I am prepared to remove and clean the strainer - I plan to either siphon or drain my half tank of diesel. All I need is the wrench size (the 1 1/4 inch one I bought is too small).