2-cycle engine question

Background: Homelite chainsaw runs, but it's not oiling the chain. The oiler
seems to require pressure from the engine, which (1) pressurizes the oil
reservoir and (2) operates a diaphram pump.

The pressure for these actions seems to come from a port drilled into the
crankcase. From my vague knowledge of 2-cycles, I think there would sometimes
be pressure there (during the exhaust stroke?) - that's why it needs reed
valves?

My question is, if there is crankcase pressure, would that be affected by
whether the spark plug was installed or not? When I spin the engine with a
drill (plug removed), I do get some action on the pump diaphram, but not very
much. I'm wondering if this is part of the problem, or just a symptom of
cranking with the plug out.

Thanks,
George

I may show my ignorance, but as I remember it, there is pressure on the
crankcase
when the piston is going down (the power stroke). The exhaust gas exits via
a
port in the side of the cylinder, usually.

The downward travel of the piston creates pressure in the crankcase against
the reed
valves which forces the mixture into the cylinder.

As the piston goes back up, vacuum is created and a fresh charge is drawn
into
the crankcase through the reed valves.

So there is alternating vacuum and pressure in the crankcase.

If your piston rings are good, the crankshaft seals are not leaking, and
the reed
valves are working as they should, I don't think the spark plug being out is
going to decrease the pressure in the crankcase enormously.