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Unread 08-27-2015, 05:08 PM   #1
blamc70
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1981 CJ7 
 
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PCV line connections

I'm working on my 1980 CJ7 (with a 1981 258 engine) that I recently purchased. I've replaced the valve cover with an aluminum one, and put on a new "T" shaped PCV, in place of the old "L" shaped one that was on there previously. I'm finding that the PO did a lot of things that were maybe not exactly correct... so I'm trying to figure out what things I need to correct as I go along. This is my first CJ, so it's all new to me!

My question is regarding the hose that goes to the back side of the PCV... the "smaller" side. I know that this should go to the third port (from the firewall) on the charcoal canister. However, my canister is presently "plumbed" differently than the diagrams I've seen. Currently, starting on the side nearest the firewall, the first port on the canister is going to a tee at the front of the carb, with lines off of each end of the tee going to ports on the front of the carb. The second goes to the fuel tank vent. The third goes to the fuel filter return. The final port on the canister is going to a tee, with one end going to a port on the fuel pump, and the other going to the bottom part of the carb.

Given that, where should I connect the line from the back side (smaller side) of the PCV? Should I add a tee on one of the existing lines off of the canister? Or should I move one of the canister lines somewhere else, and connect the PCV directly to the canister?

Hopefully I've explained what I'm seeing clearly enough! Any suggestions would be very much appreciated!

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Unread 08-27-2015, 05:16 PM   #2
Matt1981CJ7
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It sounds like a PO fubar'd the canister plumbing.

The fuel filter return should go to the fuel tank, not the canister. There's a considerable amount of gas that goes thru that return line. It will saturate and ruin your canister, if it isn't ruined already. I'm not sure why anything related to the canister would be plumbed to the fuel pump.

I suggest you consult your factory service manual and connect things properly.

Matt
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Unread 08-27-2015, 08:07 PM   #3
blamc70
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Thanks Matt. How can I tell if my canister is ok?
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Unread 08-27-2015, 08:18 PM   #4
blamc70
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I'm sorry I realized I just said that wrong. The final line is not going to the fuel pump from the T, it's going to the lower half of the distributor. Sorry about that.
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Unread 08-27-2015, 08:29 PM   #5
Mike Romain
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Ouch. The top line on the canister valve goes to the valve cover side nipple on the carb with a T fitting to the distributor.
The line below that goes to the PCV valve T.
The other two lines sound right.
The gas filter has a return line that needs to sit at the top of a level filter and it goes back to the gas tank.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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Unread 08-28-2015, 04:47 PM   #6
blamc70
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Ok, I think I'm starting to get the picture, based on feedback here, and the info I'm finding in the service manual.

My CJ7 currently has a fuel filter that does NOT have the 2nd outlet. What I believe to be the fuel return line (?) is, as previously indicated, connected to the charcoal canister on the 3rd port (from the firewall), which is where the smaller port from my PCV *should* be connected. Assuming that is correct, I believe what I need to do is replace the existing fuel filter with one that has 2 outlets, and connect the smaller, top outlet to the fuel return line, then connect the small port from my PCV to the charcoal canister on the 3rd port. Does that sound about right?

Please refer to the 2 pics here. One is of my existing fuel filter, and the other is the space between the charcoal canister and the engine. You can see the green line, which is connected (correctly I believe) to the 2nd port from the firewall on the canister. The line that I *think* is the fuel return line I have marked with blue tape. I've traced it back as best I can... it runs right beside the green line all the way down the drivers side to the back at the fuel tank. It's difficult to tell where exactly it is connected to to be honest.

What do you guys think? Have I got it right?

Thanks!
20150828_170705_resized.jpg   20150828_170806_resized.jpg  
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Unread 08-29-2015, 05:13 AM   #7
Mike Romain
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That sounds better. The green line is the gas tank vent and the return runs beside it. When you hook up the return, watch it very carefully, lots are disconnected because they sprouted leaks. Mine just sprouted one and it emptied my gas tank on me. It must have got a syphon action going. I thought it would just stop leaking when I shut it down, was going to fix it later, but nope, drained her dry.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-30-2015, 09:27 AM   #8
blamc70
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You called it! Once I connected everything correctly, I discovered a fuel leak. So for now, I've temporarily reconnected the way the PO had it, until I can get the tank pulled and see what the problem is. I suspect maybe the fuel line near the tank.

I suppose the only way I'm going to get to the top of the tank is to drop it... oh well, yet another thing to add to the list!
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Unread 08-30-2015, 09:45 AM   #9
Mike Romain
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Quote:
Originally Posted by blamc70 View Post
You called it! Once I connected everything correctly, I discovered a fuel leak. So for now, I've temporarily reconnected the way the PO had it, until I can get the tank pulled and see what the problem is. I suspect maybe the fuel line near the tank.

I suppose the only way I'm going to get to the top of the tank is to drop it... oh well, yet another thing to add to the list!
You can leave the PCV set up for the vent canister and just block the return line for now. The return line is supposed to com off the top edge of the filter so any vapours produced on a hot shutdown get blown back to the tank preventing vapour lock.
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86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
Some Canadian Bush Jeep Runs and Build Photos: http://mikeromainjeeptrips.shutterfly.com (10 new albums added Sept 16/10)
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Unread 08-31-2015, 07:28 AM   #10
blamc70
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Thanks Mike... I did that yesterday at your suggestion and at least have it running again with no fuel leak. I'll check into dropping the tank in the next few weeks to see about fixing the leak! I do appreciate all of the suggestions and help!
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