Fuel questions

ROBCDN3 · Post by **ROBCDN3** » Wed Sep 28, 2016 6:17 pm

This is a couple of questions for tech support. First does a new fuel filter install before or after the fuel pump? Second questions is why is there a vent line from the air breather to the fuel line ? Any and all please jump in. Cheers Rob 71 M38a1c

4x4M38 · Post by **4x4M38** » Wed Sep 28, 2016 6:28 pm

Rob,
The M38A1 has the fuel filter installed in the tank. From there the
fuel line goes directly to the carburetor.

All fuel tanks have to be vented sonehow. The jeeps equipped with
fording ventilation equipment vent the fuel tank to the air cleaner.
When fording, the air cleaner has an extension to the intake raising
the air intake as well as venting to above the windshield.

On vehicles not equipped with fording ventilation equipment (later A1's)
or vehicles that had it removed have a vent fitting installed right at the
fuel tank.

See Wes' photo pages regarding fording ventilation.

Take care,

ROBCDN3 · Post by **ROBCDN3** » Wed Sep 28, 2016 6:43 pm

Thanks Brian. This fuel filter is an add on as a secondary to the tank filter. On the vent line coupled to the fuel line this just seems strange to me. Introducing air into the fuel flow. Cheers Rob 71M38a1c

4x4M38 · Post by **4x4M38** » Wed Sep 28, 2016 8:02 pm

Rob,
If your in tank filter is working properly you do not need a second one.
You may be causing a restriction in your fuel line.

Venting the tank. Take a straw and put one end in your mouth and
hold a finger over the other end.

Now suck on the straw.

That's what happens if you don't have some way
to introduce air into your tank.

Take care,

Post by **wesk** » Wed Sep 28, 2016 9:08 pm

Rob,
In a normally plumbed M38A1 with or without the full fording system there is no vent line connection to the fuel line that runs from the fuel tank to the fuel pump. What connection between the vent system and the fuel delivery system are you referring to?

ROBCDN3 · Post by **ROBCDN3** » Thu Sep 29, 2016 11:00 am

Yes Brian thanks again for your analogy.
Wes. I had two line tyraped together and one went to the air breather(I have a pancake style same as the 151`s) The other line droped down to a tee and was for the dash primer pump. So thanks ,the question what tee made me cut the tyraps and trace the lines and make a positive analysis.The one way valve at the tee was fouled at the check ball and probably leaking back to the primer pump which in turn was leaking back to the manifold. So out withall that crap and we will see if she is still stinky at start up. Cheers Rob 71 M38a1CDN3