Packard Forum Index » Pre-War (1899-1942)

After being unable to solve my fuel supply issues with an electric fuel pump, I am installing the original fuel/vacuum pump after finding out I need the vacuum pump for the wipers. This is probably a dumb question, but the one port on the vacuum pump in marked "in" - does the 'in' port go to the fitting on the intake manifold, or, does it go the wiper motor. dealing with vacuum, I am a little confused on what 'in' is.

If it is marked as most pumps would be the IN port would go to the wiper. The pump is in series between the wiper motor and manifold so normally the pump valves will let the stronger manifold pull air right thru the pump. Under engine load when the manifold becomes weaker than the pump then the pump valves will start to function. Their configuration blocks the manifold and the now stronger pump will pull air in from the wiper motor and exhaust it out to the manifold.

To verify it is labeled as most are you can manually operate the pump and place your finger over each port. The port with suction would go to the wiper motor.