Merc vacuum wiper pump

Hi guys the dual action fuel/ vacuum pump on my 50 merc didn't have the vacuum pump plumbed in can anyone tell me which port goes to where please.
Cheers guys Charlie

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I need to look that up myself this week. Mine is 55 Olds motor, but same dual pump. I thought I tried looking at one once and my head hurt, as I thought the pump lines hooked to manifold and wiper motor?

It's easy to tell which is suction on the pump, just hold your finger over the open fitting at idle

I might find out in my manuals.

 

I believe the intake for the pump goes to the manifold. The suction from the pump goes to the wipers. The manifold vacuum ****s through the pump and then on to the wipers if that makes sense.

 

BJR has it right. One hose from pump to manifold, another from pump to wiper motor. The pump should be marked which is which.

As long as you have vacuum the engine vacuum holds the pump open and it does nothing. When vacuum drops, as when climbing a hill, the pump kicks in.