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Author Topic: fuel pump identification and fuel line/vacuum lines  (Read 267 times)

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Offline MikeP

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fuel pump identification and fuel line/vacuum lines
« on: September 17, 2019, 02:37:07 PM »
so i need help with figuring out this fuel pump and would m38 fuel lines hook up to it if im going to be using an m38 fuel tank also whats the thingy behind the exhaust pipe and does it need to ever be attended to and what the line coming from the bottom of the engine block the line from the manifold is for the wipers
1950 willys cj3a

Offline scoutpilot

Re: fuel pump identification and fuel line/vacuum lines
« Reply #1 on: September 18, 2019, 12:07:51 PM »
Very hard to determine with all that gunk on it.
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Offline Rus Curtis

Re: fuel pump identification and fuel line/vacuum lines
« Reply #2 on: September 18, 2019, 12:25:33 PM »
Mike,
Yes, a good cleaning will do wonders to help figure out what's going on.  But, I'll attempt to provide some info - understanding I'm not that familiar with the L-head - and hopefully more info will follow. 

My approach is to study images of other engines (or any component, for that matter) to help me understand what I should be seeing.  If you have a Service Manual (SM), it will help a bit.  In Section D, there are some images of what the L-Head should look like. 

I am not fully comfortable with searching in and around the CJ-3A website and cannot find a dedicated link to illustrate helpful images on the flat head.  I did notice a link back to the CJ-3B website on Joe Caprio's CJ-3A and that was pretty good:



I also found a bunch of images of Andy Gil's rebuild:



This shows a different type fuel pump (glass bowl) and I suspect there's more images available but I'm not quite up to speed on searching for them here yet.

Based on what I've seen (and can remember) I'll offer some opinions:

1.  That fuel pump looks like a dual function or Fuel And Vacuum Pump.  It appears to have a metal bowl on top and the bottom, covered in gunk, looks like the vacuum portion.  The metal tube attached to the pump is probably the line to your carb.  The other fitting (with the severed rubber line still visible) is probably from the hard line that attaches to the tank (supply line).  Down at the bottom of that image, there appears to be a metal tube with the remnants of a rubber line.  This is probably the line from the tank.   Whether an M38 fuel line would attach or not will probably depend on the type fittings the tank has.  If that line is a 1/4" fuel line for both the 3A and M38, then it seems possible the fittings would be the same size.

2.  The "thingy" behind the exhaust pipe.  Are you referring to the rubber hose just in the picture frame on the right that is aft of the exhaust or the protrusion on the side of the engine block underneath the exhaust?  Rubber hose?  Don't know, would need to see where it goes.  The protrusion on the engine block?  That's the oil pump and I don't believe you'll need to do anything to it as long as you've got oil pressure.  If you do any engine rebuilding, then you'd have to follow the SM steps to ensure realignment.

3.  The line coming from the bottom of the engine block looks to me like the pressure line for your oil pressure gauge.  Follow the metal tube through the firewall and you should see it attached to the oil gauge (or lined up to the hole where the gauge would be.

4. "The line from the manifold is for the wipers." Edited: If you are referring to the rubber hose running in front of the fuel pump that crosses the front of the engine, that makes me think someone disconnected the hose from the vacuum pump at the bottom of the fuel pump.  My bad.  I slipped into the F-head thinking again (about the fourth time while thinking through this post- but didn't catch this until now). Y'alls manifold is on the driver's side.  Manifold vacuum varies while driving and the vacuum pump on the bottom of the fuel pump provides help to keep the wipers sweeping more consistently (this part still applies).  Study Caprio's  3A and it shows the entire wiper vacuum plumbing.


Added:  Great detail on your images but, had you stepped back a bit to capture more in the image, viewers would most likely be able to jump in with even more information to issues that would help.
« Last Edit: September 21, 2019, 09:38:38 AM by Rus Curtis »
'54 CJ-3B "Green Gruntt"
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Offline MikeP

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Re: fuel pump identification and fuel line/vacuum lines
« Reply #3 on: September 20, 2019, 11:54:03 PM »
thats some amazing info and ill see about getting the numbers off the fuel pump saturday since i dont work
1950 willys cj3a

Offline MikeP

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Re: fuel pump identification and fuel line/vacuum lines
« Reply #4 on: September 21, 2019, 12:23:38 PM »
so i used up a whole can of brake clean just to get the pump clean enough with scraping to reveal the only 2 letters i could see which is AC or CA depending on how you look at it
1950 willys cj3a

Offline scoutpilot

Re: fuel pump identification and fuel line/vacuum lines
« Reply #5 on: September 21, 2019, 12:30:21 PM »
You will wind up taking the pump off because the model number is stamped into the mounting flange.
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Offline MikeP

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Re: fuel pump identification and fuel line/vacuum lines
« Reply #6 on: September 21, 2019, 01:34:50 PM »
well i took off the pump even though i didnt want to yet cause im saving every penny for the willys overland tub kit but i got the numbers and they are 9353
1950 willys cj3a