I have a 1984 300D. It runs great for a while with plenty of power, then a short time later it runs like it is sucking air. I changed both filters , it drove the same. To try and isolate problem I ran a feed line and my return line to a small bottle as if to do a diesel purge. I started the car and noticed there is no fuel coming from return line. If I pump primer pump I get fuel thru return. Thanks for your help. This is my first post but have been reading forum about 3 years. I have always been able to solve my problems by searching.

If when you pump the hand primer you get fuel return but do not get fuel retrurn when you crank the engine I would be thinking the maybe the fuel supply pump is not working correctly. Loosen the banjo bolt up by the secondary filter fuel inlet and crank the engine and see if you get some strong spurts of fuel. Things that can happen to the supply pump: gunk inside can keep the valves from sealing, valve springs can break or rust through, valves can wear out, the pump piston return spring can break and there is a small O ring inside of the pump where a rod pusnes on the pump piston. Less likely but easy to inspect there is a tappet and roller that rides on the IP cam that can wear out.

__________________
84 300D, 82 Volvo 244Gl Diesel

I forgot to add that If it is the supply pump not working (at least back in 1986; the last time I worked in fuel injection) there used to be a seperate rebuild kit for the supply pump. It has all the valves, O rings and gaskets in it. Right behind where your hand primer pump is there should be a plate with the supply pump number on it. You will have to ask the local fuel injection shop concerning availability and price.
Not a good pic but you can see the number plate.

__________________
84 300D, 82 Volvo 244Gl Diesel

Thankyou, I removed the banjo bolt and cranked engine, didn't get much fuel. I have an old lift pump, will try replace with that.

I replaced lift pump and still, same problem.

Were you getting your fuel from the fuel tank?

__________________
84 300D, 82 Volvo 244Gl Diesel

You might try running a hose from the primary filter into a clean antifreez container (or some other container with a small neck so fuel will not splash out when you are moveing) filled with enough diesel and drive the car for a couple of miles. (There should be room over by the window washer water container.) This will bypass any problems that might be caused by the fuel tank and tubing (restricted or clogged tubing, tank screen or tank vent).
Also is there any other symptoms: smoke, leaks, unusual sounds. "It runs like it is scuking air" did that mean it was loss of power and running erratic or just loss of power?
Will the engine start normally and idle OK?

__________________
84 300D, 82 Volvo 244Gl Diesel