I’m sure there are other ways to do it but, if you have a rebuildable pump, disassemble the diaphragm assembly and disconnect the fuel lines. Have someone crank the engine and observe the pump arm to see if it moves. Others will be along shortly with a better way.

Martin
'62 Chevy C-10 Stepside Shortbed (Restomod in progress)
'47 Chevy 3100 5 Window (long term project)
‘65 Chevy Biscayne (Emily)
‘39 Dodge Business Coupe (Clarence)
“I fought the law and the law won" now I are a retired one!
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USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)