B275 CAV fuel pump problems...help.

This weekend, I was purging the fuel system on my 1961 B275 diesel (B414 Engine) to get rid
of the summer diesel that I had left in it (I know, I'm a bonehead).
It recently hit -45C with the windchill. Anyways, this weekend it was
only about -5, so I figured everything would be less frozen.

Here is my problem: I followed the directions for purging the fuel
system, and I get fuel flowing through the filter to the pump. I
can't get fuel out of the LOWER purge screw on the fuel pump. The
upper purge screw is fine, I get fuel coming out using the manual
pump on the other side of the tractor. When I try to start the
tractor (after having loosened off two of the fuel line connections
to the injectors in order to finish bleeding the system), it catches,
but then seems to die of starvation...

I have checked the air intake, I have defrosted all the fuel lines, I
have drained the fuel tank and refilled it with winter diesel, I have
emptied the contents of the fuel filter and refilled with fresh, I
have taken off every single (almost) line and blown it out. The fact
that I don't get fuel coming out of the lower purge screw seems to
tell me that there may be something wrong with the pump.

Has anyone got any ideas, or run into this problem before?

Phil,
Finch, Ontario

Thanks for the help, but that is the problem...I can get fuel out of the top air bleed screw with no problem. If I loosen off the injector unions, air and fuel SHOULD escape when either the engine is turned over OR the manual fuel pump is actioned. My neighbour told me to loosen off two of the injector unions, and that turning the engine over SHOULD force air and fuel out of the injector unions...but I can't even get fuel out of the injector union with the manual pump...The engine will catch (if I use the glow plugs) but then starve after a few seconds of very rough running.
I'm stumped.

Her's a pic of the fuel injector pump...

1)adequate fuel, fuel shut-off fully open, engine stop control in stop position
2)loosen air vent screw at water trap until fuel free of air bubbles flows from vent screw. tighten.
3)loosen spill pipe banjo bolt at top of fuel filter canister. Use hand pump til fuel free of bubbles, tighten banjo while fuel still flowing
4)Loosen injector pump inlet pipe and use hand pump til fuel free of bubbles, tighten while fuel still flowing
5)loosen lower vent screw on injector pump body and use hand pump til fuel free of bubbles, tighten while fuel still flowing
6)loosen upper vent screw and use hand pump til fuel free of bubbles, tighten
7)turn engine 1/2 turn , bleed the lower vent screw again as above.
8)push engine stop control in to run position
9)loosen all injector unions at the injectors,
move the governor lever to full open. Turn the engine with the starting motor til fuel free of bubbles from all unions, tighten unions.
10)start the engine
if it runs smooth you are done. If not loosen each injector union for a few seconds, in turn, while running.

This is atwo man job more or less as you need someone to hand pump it and one to loosen and tighten the vents or other connections while fuel still flowing.

This well better get you going as I just spent 20 minutes typing it. If it ran before this should do it.

Thanks for the description...with the exception of the air vent screw at the water trap (which I don't have), the procedure that you outlined is exactly what I have in my owners manual...which is exactly what I did.
What I'm wondering is why there is no fuel coming out of the bottom vent screw on the injection pump. Assume that I have done everything else up to there with no problems...
Does this indicate a problem with the injector pump?
I'm assuming that it shouldn't take 4 minutes of pumping the manual fuel pump to get fuel from the injector pump inlet pipe to the lower vent screw on the injector pump housing...?

Thanks,
Phil