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Primer Pump Connections

Posted: Tue Mar 25, 2014 9:25 pm
by M606BR
I've got a primer pump and I intend to install it in my M38. I noted that both tube nuts attached to the pump are different from the regular inverted flare nuts I use to deal with. How should I do the flaring job in the tubing in order to connect them to the pump?

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Another questions:
1) Besides the inlet ball and spring installed inside the inlet connector of the primer pump, is it really necessary to install a check valve in the "T" in the main fuel line?

2) My primer pump doesn't have the elbow as described in the primer pump from the parts list. Should I install one in my primer pump by removing the inlet connector and replacing it in the other end of the elbow?

Posted: Tue Mar 25, 2014 10:12 pm
by wesk
The tube nuts are compression fittings. You do not flare the tube. You slide the tube through the nut and then through the ferrule (brass sleeve) then insert tube snugly in the receptacle. Then slide the nut & ferrule down into the receptacle maintaining pressure on the tube towards the receptacle and tighten the nut. As you tighten the nut it compresses the ferrule (brass sleeve) which cuts into the tubing and secures and seals it.

https://www.youtube.com/watch?v=aFpZfr0YQ28

Questions:
1-No. I see no check valve next to the "T" on the frame rail. I see a manual shutoff valve for turning the fuel supply off.

2-Yes, unless you have extra tubing length and room above the hand pump to route the tubing. The Elbow gives you a straight towards the firewall route for your tube.

Use the complete instructions in my photo album under M38 fuel system:
http://www.willysmjeeps.com/v2/modules. ... _album.php

You click the photo twice to enlarge it.

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Posted: Wed Mar 26, 2014 12:12 pm
by M606BR
Questions:
1-Yes, the check valve prevent fuel under pressure when the engine is running from forcing it's way past the hand pump's check ball and out through the handle into your lap.
Wes,

Thank you for answering my questions, but I didn't understand well your answer I quoted above. I thought the reason for a check valve attached to the "T" in the main fuel line was to avoid fuel to return to the main fuel line.

I've read the primer pump installation instructions from your photo album and didn't find any mention to the check valve in the "T" in the main fuel line. The instructions only mention a 3/16 x 1/8 male connector to be installed in the "T". Is that 3/16 x 1/8 male connector (P/N 7375063) actually a check valve to be installed in the "T"?

Posted: Wed Mar 26, 2014 7:24 pm
by wesk
Sorry Luiz,

My mistake. I corrected my answer to your question # 1.
1-No. I see no check valve next to the "T" on the frame rail. I see a manual shutoff valve for turning the fuel supply off.
The two check valves that are in the primer pump are the only two.