Fuel Vent Line on M38

rgmutchler · Post by **rgmutchler** » Fri Mar 13, 2020 3:04 pm

I am in the process of installing a wiring harness and in that process once I got the fuel gauge working I looked at the fuel tank vent.
I am having some problems determining how it is routed. It appears that it follows the path of the fuel tank sender wire and then exits out a hole in the left top of the firewall. (hole #18 in Ryan's book). After coming out that hole it goes across to the air cleaner.

So when I look at the route the lower cowl support has one hole in it and I used it for the fuel tank sender wire and loom. But I don't find a separate hole in the lower cowl support for the 3/16 vent line. I replaced the lower cowl support and maybe it wasn't replicated in the replacement part.

In any case I don't want to route the line around the lower cowl support.

This picture shows the path the fuel sender wire through the lower cowl support.
I have spent a lot of time in the picture albums and the manuals looking for a picture. I am not saying there isn't one, just that I haven't found it. So any comments or info is appreciated.

BobW · Post by **BobW** » Fri Mar 13, 2020 6:09 pm

Here is what my 1952 looks like. It is probably original. Your Jeep has an early serial number so it could have been different then.

RonD2 · Post by **RonD2** » Fri Mar 13, 2020 7:48 pm

Hi RG,
If it helps, mine are exactly like BobW's photo.

I also snuck a ground wire into the loom with the sender wire. It goes from the sender body top plate to the same ground used for the gauge panel.

Wes' advice.

rgmutchler · Post by **rgmutchler** » Fri Mar 13, 2020 9:03 pm

Thanks guys, I was pretty sure that had to be the answer. I guess I will drill some holes and let the vender that I bought the lower cowl from in case he wants to research the second hole for the tank vent.

RonD2 · Post by **RonD2** » Fri Mar 13, 2020 10:09 pm

RG,
I edited my post to add a photo of mine, right after your post.

And if you'd like some measurements let me know and I'll see what I can do.

Post by **Ryan_Miller** » Sat Mar 14, 2020 6:20 am

Ground wire is a good idea!

I did the same thing. The fuel sending unit really needs it to work reliably in my experience.

rgmutchler · Post by **rgmutchler** » Sat Mar 14, 2020 8:13 am

Thanks Ron, it would be good to know how far below the hole for the sender unit wire the hole for the vent tube is. Of course a lot will depend on the clearance to get a drill in there.
As to the grounds i have added some and it does help. I have grounded the gauge cases to each other and then have a ground up under the dash.

RonD2 · Post by **RonD2** » Sat Mar 14, 2020 6:42 pm

Hi RG,
Sorry for the delay. A little tricky getting good measurements with stuff in the holes, but this should be pretty darn close.

I left one critical measurement off the drawing: the bottom edge of the bottom hole is 9-9/16 inches above the drivers floor, measured straight (not following the curve) up the slope of the rear edge of the cowl support brace.

Measured a different way, the straight line vertical distance from the bottom edge of the bottom hole to the drivers floor is 9-1/8 inches.

Hope this is clear enough to help. Please let me know if you need anything else I can do.

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Post by **wesk** » Sun Mar 15, 2020 2:11 am

RG Take a look at the passenger side cowl brace.

We tend to forget these jeeps were built with the available option of left or right drive for export purposes.

rgmutchler · Post by **rgmutchler** » Sun Mar 15, 2020 11:09 am

Ron, Thanks for the measurements.

Wes, I looked at the right lower cowl support. It doesn't have any holes in it but then it is a replacement part also.

RonD2 · Post by **RonD2** » Sun Mar 15, 2020 11:28 am

It never ocurred to me to look at the right side! So I just did and can confirm it has the same measurements as the left. Much easier to measure without stuff in the holes. Thanks Wes!

Wes' photo also reminds me that I need to locate and punch (not drill) the holes for my floor drains.....