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I'm just getting around to hooking up my wipers. Everything was disconnected when I got the car. My vacuum pump on the fuel pump is not operating, so I have connected the wiper motor directly to the vacuum port on the intake manifold. The wiper motor moves very slowly about halfway and then stay there. My question is, does the vacuum from the manifold provide enough vacuum to operate the wipers, or must the fuel pump vacuum be operating for them to work. I'm trying to decide whether my next step is the fuel pump or the wiper motor.

I would send my fuel pump to J Gould for a rebuild and the wiper motor to Ficken wiper service for the same.

To answer you question directly, an engine in good condition and tune should have 18-20 inches of manifold vacuum, more than adequate to give good wiper operation at all times except under heavy acceleration. The vacuum booster pump only provides vacuum boost under conditions of acceleration. So if you engine is up to snuff and at idle the wipers fail to function properly when connected diretly to the intake manifold, either you've got some vacuum leaks along the line or the motor needs rebuilding.