M38 Vacuum Lines

j3shane · Post by **j3shane** » Wed Jan 27, 2016 12:08 pm

The vaccum lines for my M38 are all disconnected and not routed properly, or missing all together. I saw the chart for the proper line routing so that will help.

My M38 has a Solex carb and the civy fuel pump with two tubes that curve up - they aren't connected to anything. The vacuum for the intake is capped off and the vacuum line coming from the air filter tube is hanging.

From the diagram it looks like the air out from the fuel pump goes to the intake manifold. Is this required to be connected?

It looks like the air intake tube connection connects to the carb. I don't see a connection on the solex for it. Is it needed?

Started runnig bad when you give it gas so I am replacing the plugs, putting a new solex on it, putting a fuel pressure reg on it, and checking the timing. Just wanted to fix anything that was vacuum related that could be causing issues as well....

4x4M38 · Post by **4x4M38** » Wed Jan 27, 2016 1:56 pm

If you have vacuum leaks it can cause problems like you are describing.

Can you post a couple of photos?

j3shane · Post by **j3shane** » Wed Jan 27, 2016 4:27 pm

It will be a few days before I can get picks but basically there is no vacuum connected to the motor at all, or wipers. The vaccum connections to the fuel pump are not connected to anything and not sure where to connect to the Solex carb. Will post pics when i get them. Thanks

Post by **wesk** » Wed Jan 27, 2016 11:24 pm

There are no vacuum connections that go to the carb on a M38 no matter which carb you use.

The civvy vacuum/fuel pump is plumbed the same as the military. Inlet air port is connected to the vacuum wiper T and outlet air port to the intake manifold. If unsure which port is which run the engine and the inlet air port will suck and the outlet air port will blow.

Will need to see photos of the top and both sides of your engine and the firewall to offer workable advice. To add photos to a post here you will first need to put your photos on a host web site. Then you link the photos to your post using the photo's URL. If you wish to open a photo album in our member's photo album page request one here: http://www.willysmjeeps.com/v2/modules. ... wforum&f=9

skyjeep50 · Post by **skyjeep50** » Thu Jan 28, 2016 11:46 am

Here's a pic of my M38 engine with a Solex carb. The copper lines connected to the military vac/fuel pump are original. You can see what Wes referred to - line to the intake manifold and up to the wiper "T". If you don't have the vac/fuel pump you also won't have air flowing through the lines to the distributor - helps keep the waterproof distributor cool.