Fuel Check Valve?!

J

JeepsterCJ5

New member
Ok......... so I just finished putting the 360 in my CJ5 got everything back in place and bolted down. I can fuel it by priming the carb.. it runs great.. but I'm not getting any fuel to the carb through the lines. A friend of mine said the check valve might be bad, but I can't find them anywhere on any parts site to buy. I am replacing the fuel pump tomorrow but if that doesn't fix it I'm stuck again.
My question is... does anyone know where to find them.. or even better eliminate the damn thing!..lol
Please help!! I'm going through withdrawals.. I have been down since March lol No wheeling all summer it's like torture!!
 

Are they talking about the rollover valve? I'm still learning about Jeeps but Isn't there on tucked up underneath by the gas tank?
 
Rollover valves are only found on the later models. CJ's don't have them. For that matter, I've never heard of a check valve either on the CJ's fuel lines. Make sure the fuel lines are free of kinks and restrictions. Also, check the rubber fuel lines for cracks or loose clamps as this may not let the lines prime with fuel.


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The lines are good.. and the check valve is mounted on the drivers side in the rear behind the tail light.. it's a stock feature it's even in the chiltons manual.
I'm just not sure if its really necessary.
but I think I finally figured out the third line...
one fuel .. One return... one canister
 

SteelHeadz said:
Rollover valves are only found on the later models. CJ's don't have them. For that matter, I've never heard of a check valve either on the CJ's fuel lines.

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Hey Mickey I think you are not totally correct on the lack of a rollover/check valve on a CJ. In fact there are two. From the tank first comes the liquid check valve followed by a "rollover" check valve. (1977 Jeep Tech Service Manual, Page 4A-18, Fig 4A-17)

Now, I said not totally correct, and you are not totally wrong either as both the valves are on the emission vapor side of the tank that leads to the charcoal canister, not the supply line.
 
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Wow, good to know. I didn't see any roll over valve on my fuel tank when i took it out to weld on the filler neck.:???:
 
If we are referring to the check valve located directly behind the drivers tail light, is this a necessity? I have finally determined that my jeep stalls due to over pressirization of the fuel tankm therefore flooding me out. right now the vent lines are free from the canister and I have not had the issue. Can I replace the gas cap with a vented cap and run the vent lines back into each other?
 

What do you me by free of the canister? As in not attached to the canister? Also, has the return fuel line from the fuel filter been removed? This could be a sourse of pressure build up. The return line should be on the upper outlet nipple of the filter to work properly.

I may be wrong but I drought if you can even buy a vented gas cap in the US today. The whole point of the charcoal canister is to create a closed loop fuel system to prevent gas vapors from entering the atmosphere. (pollution and the ozone layer issues) The vent tubes on the tank end up at the canister. The vapors are collected in the charcoal and then the next time the engine is started the vapors get sucked off into the carburetor and are burned. The Liquid Check Valve works to prevent liquid gas from entering the line and compromising the integrity of the charcoal. Once the charcoal is saturated with liquid gas the canister is done. The rollover check valve as the name indicates prevents gas from entering the line in the event of a rollover. Again liquid gas in the charcoal is not good but also once upside down if not checked gas could leak out of the system and be a fire hazard.
 
Saddle Tramp, yes the single vapor vent line from the top of the liquid vent canister is not attached. The connector it is supposed to go is broke. The single vent line which is supposed to go to the charcoal canister loops behind the passenger front fender. I would assume the PO removed the charcoal canister when he performed the engine swap as there is no charcoal canister. I have been trying to locate both of these items to put all back to the way it should be. I have not even been able to find them at any of our local junk yards.

As far as return line from the fuel filter, there are 2 filters on the jeep, neither has a return line, they are both clear plastic with an inlet and outlet.
 
Sounds to me like your problem primarily stems from not having a fuel return line as it is designed to eliminate fuel vapor issues. The picture is what you should have for a filter and only one filter is necessary, not two as you currently have. The supply line is coming into the filter on the right side of this picture. Note the two out flows. The top one goes to the return line. The return line connects to the extra nipple in the sending unit on the top of the gas tank. The lower outflow line on the filler goes to the carb. It is not uncommon to hear of guys removing the return line during a mod but in the end the line always needs to be restored in order for the engine to run properly.
 

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  • AMC-CJ I6 & V8 Fuel Filter.jpg
    AMC-CJ I6 & V8 Fuel Filter.jpg
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Saddle Tramp,
Thanks for the explanation and pic. I will stop by the auto parts store and see if I can acquire one of the proper filters. My jeep still does not have a charcoal canister nor does it have the liquid fuel vent canister. Any idea where I can find these. I have gone as far as calling my local jeep dealer and was told they are unaware of what I am talking about?
 
I'm glad we got saddle tramp back on the right track...lol but I'm still stuck. I put a new fuel pump on and it didn't resolve the issue. I learned a bit from reading through saddle tramps problem, and I am gonna post a pic of my check valve and (other unknown part) behind my tail light.
But the question remains... can this be eliminated.. or can I find another.. the parts stores around here look at me like I just asked for a flux capacitor for a Delorian.
 

The item behind the taillight is known as " liquid fuel vent canister" It is part of the vapor venting system for the gas tank. My 82 has two vent lines from the tank to this canister, then off the top of this canister comes a single vapor vent line to the passenger front to where the charcoal canister is supposed to be. I have been told that both the liquid fuel vent canister and charcoal canister were part of the smog control system. Mine are currently bypassed as I cannot find them anywhere.

Question: have you verified the new fuel pump is drawing fuel from the tank? There are two fuel lines along the frame, one is to supply fuel the other is part of the vent system. Are you on the right line?
 
Here is a picture of the emissions Controls on the CJ fuel tank. My scanner is down so I had to just shoot a picture of it. Also, I crawled under my 1978 CJ5 to verify what I had going on. Mine is set up as described below.

The two valves behind the drivers’ side tail light are the two valves we have been talking about, the Liquid Check Valve and the Rollover Check Valve. In the picture you see two hoses coming out of the tank and going into the bottom of the first and larger valve; this is the liquid check valve that prevents liquid gas from entering the system. From there one hose leaves the Liquid Check Valve and goes to the other smaller valve; this is the Rollover Valve. 82CJ7JEEP is incorrect when he called the first valve the Liquid Fuel Vent Canister. No such animal is mentioned in my 1977 OEM Tech Service Manual unless things changed for 1982 but it is easy to see why many different names for these pieces are floating around.

From the Rollover Check Valve a hose then goes to the Fuel Vapor Storage Canister aka the Charcoal Canister in the engine bay. The book calls it by both names.

I agree with 82CJ7JEEP in that if you have a new fuel pump and still are not getting any gas to the carb you must not be getting fuel out of the tank. Likely culprits are:

  • The pump is bad (even new it could be but not likely)
  • There is an air leak between the gas tank pick up and the pump.
  • The filter on the tank pick up is clogged or the pick up is bad.
  • The after the pump to the carb hose & filter system has troubles.
  • As 82CJ&JEEP asks, are you trying to draw fuel on the return line.
Have you tested to see if you are getting gas at the pump?
 

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  • 1977 JEEP Fuel Tank Emission System.jpg
    1977 JEEP Fuel Tank Emission System.jpg
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Well I know that the pump is good.. I took it off my old 304 which was a running motor.. not sure the pump was the issue though.
i bypassed the rollover check valve.. and still no fuel.. wondering if I should bypass the liquid check valve too.. but the last pic posted is the same one I show in my manual.
 

OK.. think I found the culprit... unfortunately I think it's the lobe one cam is wiped.. I'm almost 100% on this.. so I"m just gonna buy an electric pump and bypass it...
 
I would check out the tank and make sure the pick up is OK before starting the electric pump wiring. You will have to drop the tank to do it but if the pickup is clogged or broken an electric pump isn’t going to help. It could even be a crack in the hose at the top of the pick up.
 
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