M38a1 fuel pump vacuum section

[DCAK]

Will plugging either of the openings on the vacuum section on the lower section of the fuel pump effect the operation of the fuel pump?

[4x4M38]

Maybe not the pump but if you have an original engine/carb/crossover/24 volt distributor you might want to rethink that.

As well as vacuum wipers.

[DCAK]

Everything was disconnected when I purchased the jeep except carb to crossover.
Inlet to vacuum on fuel pump open, outlet has a plug in it. Wipers were hooked to vacuum connection below carb on manifold.

[RonD2]

Hi DCAK,
If you're interested in connecting your vent-vacuum system up correctly the manuals are free in the the downloads section of this website.
Parts aren't hard to find.
There's tons of very informative searchable posts about it in this forum.

Are you using the 24-volt waterproof distributor and the YS-950 carb?

Good luck!

[wesk]

DCAK,

Try to keep in mind you are dealing with a mechanical vacuum pump that will suck and blow all the time the pump is operated or at least strain it's lever and diaphragm trying to suck & blow. Solid blocking of intake or exhaust will result in internal damage to the vacuum side of the pump. If you have no desire to harm your pump and simply wish not to use the vacuum half then simply vent it to the atmosphere and allow it to suck from outside and blow to outside. If you wish to take advantage of it's ability to almost double the available intake suction then simply connect the suck tube to your manifold where the wiper tube is now and run the wiper intake tube to the other opening on the pump. The intake vacuum is an inadequate source for your vacuum wipers. If you continue your present direction you will not be happy when driving in the rain and accelerating or climbing a hill at the same time because your wipers will stop operating until you get your intake suction back on the downhill or let off the gas when accelerating.

Not only are the needed manuals on our download page and free for the taking but there a thousand photos in my album with nothing but learning material on them for all the jeeps our site represents and all their systems.

I have the second album on our "Member's Albums" page and in this case here is the sub-album you should review:

M38A1 fuel system:
http://www.willysmjeeps.com/v2/modules. ... _album.php

And it's sub-album "Vent & Fording System":
http://www.willysmjeeps.com/v2/modules. ... _album.php

On another note: If you are using the original military 24V waterproof distributor your vacuum system is required to ensure all explosive gases generated in the sealed distributor are sucked out and sent to the intake manifold.

[DCAK]

Answer to RonD2, I am using the waterproof Distributor and YS-950 carb.
As always thanks for all the good info.