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Early 1952 M38A1. Appears to be original military fuel/vacuum pump.
Fuel pump provides 4 psi (at cranking speed with spark plugs removed) at pump outlet fitting.
However, no fuel exits the top carb fitting when using fuel pump priming lever to fill float bowl.
Why no fuel up to carb when using lever?

Lever could be loose on the shaft, shaft could be disconnected from diaphragm link (Item Y below). It is also not uncommon for the pump to be rebuilt and the manual handle could be completely disregarded during the rebuild and only left in position to fill the hole.