Relationship between vacuum wipers and fuel pump

[Lenny]

I thought that the wipers worked off intake manifold vacuum. Now I'm learning that the "vacuum"section of the fuel pump has something to do with this too. I have also heard that some people have gone to civilian fuel pumps without losing much in the wiper function. Can someone please explain to me how this wiper system/fuel pump actually works? If I did go civilian on the fuel pump will I lose all wiper function? Some people say the vacuum wiper system was so poor to begin with anyway there wasn't much difference with or without the military fuel pump. Thanks, Lenny

 

[SturmTyger380]

Some cars from the 50's had vacuum wipers that ran only off of the intake vacuum. In these cars when you were stopped the wipers ran fine but when you opened the throttle the intake vacuum would drop and the wipers would slow down.

To help this situation the car manufacturers added a vacuum pump to boost the intake vacuum. So the vacuum comes from your intake and gets boosted by the pump. Your fuel pump has a gas pump side and a air pump side that is run off of the same cam on the engine.

If you are not into keeping your M37 as pure as possible you might think about buying a kit to convert it to electric wipers. They are much more reliable. Alan

 

[Lenny]

So Alan if I'm understanding this correctly, the vacuum originates at the intake manifold. It is then plumbed to the OUTPUT of the vacuum section of the military fuel pump. Then from there the INPUT of the military pump goes to the wipers? If that is what is going on then that would seem to make sense to me. Lenny

 

[SturmTyger380]

If yours is connected correctly the vacuum pump is always sucking on the lines that go to the wipers. So the input so to speak is actually from the wipers. The air goes into the air vacuum pump and out to the intake port.

(Army 2 1/2 ton trucks used air pressure from the brake system, Their wipers run on air pressure not vacuum.) Alan

 

[Lenny]

Yes, that makes perfect sense. I spoke to Dan at Midwest Military a short time ago. He tells me that the vacuum side of these pumps rarely fails. So I think what I'm going to do is pull the pump and see if I can manually test the vacuum section on the bench. If that looks good then I'll order a rebuild kit from them and do the fuel section myself. I've rebuilt carbs so I'm sure that I will be able to do this.

I also have a deuce and I'm also familiar with the air wipers on that too. Thanks Alan and to the other guys who responded for the advice and help. I really appreciate it. Lenny