I'm not real familiar with 240s... I'da figured a fuel pump would sorta be an all or nothing thing, but perhaps not. My '79 started cutting out frequently, and it sounds like the fuel pump is making more noise than it should...

Is that a likeley culprit?

If you're quick you can save it. I'm guessing either the pre-pump (in the tank) is not working, or its hose has disintegrated. Not getting fuel from the tank makes the main pump suck air and make noise. Too much of that eventually wears it out -- I hear.

First, fill the tank completely. The reason for this is to bring the tank to a level where gravity feed alone will keep the main pump supplied. Does it still make noise? If so, I think I guessed wrong. If it is much smoother then, make sure the pre-pump's fuse is good (#5 I think) then listen for it. Either way, if the fuse is OK, you'll be needing to pull the fuel tank sender assembly to fix the pre-pump and hose. Buy a new filter sock, sender o-ring seal and hose before beginning. You may also need a pre-pump, and a good length of 5/16" ID fuel hose (not fuel injection high pressure) depending on the rust you may find in the fuel return pipe.

There is a tool that makes removing the big bung nut easier. Just be safe around fuel; no sparks allowed.
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Art Benstein near Baltimore

Funny you should mention that... Ever since I got the car, I've pretty much known that the pre-pump pickup line has been broken... it has always cut out when at 1/2 tank or less. But last week, it continued to do it even with a full tank...

But maybe it broke completely and is sucking air? Perhaps I best start with that... The noises are definitely coming from the main pump, but it could just be the sound of air

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-Matt '70 145s, '65 1800s, '66 122s wagon, others inc. '53 XK120 FHC