Plastic Classic Forum

Has anyone ever heard of a diesel engine that doesn't have a return line going back to the fuel tank? I have a Volvo MD2B and can't find any return line.

Yes. Some of the older diesels, like your Volvo and some of the old Yanmars (among others, I'm sure) do not send a fuel return back to the tank. My old Yanmar SB12 was set up like this, though I forget the details of how the excess fuel was dealt with.

Somewhere, internally or externally, there's a passage for excess fuel to be reintroduced into the supply system, however. All diesels' fuel pumps supply (by design) more fuel than the engine can use, so the excess must be dealt with somewhere.

With this type of diesel would it be possible (and safe) to use a portable tank as would be used for an outboard motor?

Yes--temporarily, of course, which I know is your intent.