fuel tank vent problem - Page 2 - JeepForum.com

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post #16 of 34 Old 06-11-2009, 12:34 PM
CSP
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Yep the check valve came to being with the '78 model year.

The valve previous to that acts as a liquid check valve and rollover valve. The output should go directly to the evaporative canister.

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post #17 of 34 Old 08-02-2009, 08:40 AM
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Quote:
Originally Posted by keith460 View Post
The two vent lines should go to the factory liquid check valve as pictured.

Keith, where can you purchase the liquid check valve and also the rollover valve?? No luck in finding them on my end.

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post #18 of 34 Old 08-02-2009, 08:59 AM
Curt Reinhardt
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I just purchased a new combo liquid and roll-over check valve with mounting bracket from this company.

George's Jeep Parts
1044 Second St.
Osyka, MS 39657
601-542-0013
http://www.willys.net/html/fuel.html

It looks like the bottom one but is a combo and has a "tee" imput for both lines instead of a single imput.
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post #19 of 34 Old 08-02-2009, 09:05 AM
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Quote:
Originally Posted by RetiredSERE View Post
Keith, where can you purchase the liquid check valve and also the rollover valve?? No luck in finding them on my end.

Dave
See post #10 as it has the shortcut to the website for the Rollover Check Valve.

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post #20 of 34 Old 08-02-2009, 09:09 AM
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my jeep has no return line from the filter back to the tank. does this cause me to use up more gas than i should?
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post #21 of 34 Old 08-03-2009, 08:38 AM
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You would never notice any difference in gas consumption if you were to install a return line.
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post #22 of 34 Old 08-03-2009, 12:23 PM
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Originally Posted by 26679cj5 View Post
my jeep has no return line from the filter back to the tank. does this cause me to use up more gas than i should?
No, the return line returns any fuel vapor back to the tank to prevent vapor lock.

Jim
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post #23 of 34 Old 09-20-2010, 08:47 AM
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Hi, hate to bring up an old thing, but I was looking for info on why my 83 CJ7 acts like it's running out of gas, especially after some off road action. I pulled the top of the carb off to confirm, and sure enough, little to no gas.

The Jeep had been sitting for years when I got it. I went from axle to axle last winter, going through it, etc.

I dropped and cleaned out the fuel tank, replaced all rubber lines, rebuilt the carb, new fuel pump, filter, and so on. That was almost a year ago. It ran great until recently.

It began two or three weeks ago. Last week, after the symptoms were getting worse, and after pulling the top off the carb, I replaced the pump again. Cheapo AutoZone one, was still under warranty. It started running like a top again. This week, the problem has come back. What the @&$Y*&???

That's how I got here. Anyone???
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post #24 of 34 Old 09-20-2010, 09:04 AM
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Just went out and looked. My stuff doesn't look like the stuff in the picture. I have a black, plastic tank. Two lines, feed and return, to the sending unit, and two lines that "T" in to one, going to what I am guessing are check valves that are inserted to rubber grommets in the top of the tank.

Maybe the cheap gas with alcohol in it has eaten up my rubber pickup line inside the tank? It's less than a year old.
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post #25 of 34 Old 09-20-2010, 09:56 AM
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Quote:
Originally Posted by SuperDave2112 View Post
Just went out and looked. My stuff doesn't look like the stuff in the picture. I have a black, plastic tank. Two lines, feed and return, to the sending unit, and two lines that "T" in to one, going to what I am guessing are check valves that are inserted to rubber grommets in the top of the tank.

Maybe the cheap gas with alcohol in it has eaten up my rubber pickup line inside the tank? It's less than a year old.
The pick-up line in the tank from the sending unit will be steel with a plastic strainer/filter on the end. When your problem happens, have you ever opened the gas cap to see if you hear a sucking sound? If so, your tank vents are not venting. You could also have a fuel pump going bad.
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post #26 of 34 Old 09-20-2010, 12:33 PM
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Quote:
Originally Posted by scrapman View Post
The pick-up line in the tank from the sending unit will be steel with a plastic strainer/filter on the end. When your problem happens, have you ever opened the gas cap to see if you hear a sucking sound? If so, your tank vents are not venting. You could also have a fuel pump going bad.
I have a steel tube that is about ten inches long, then a rubber hose on that, then a little filter. I guess in my head I remembered it being a lot more hose. I went and pulled the old sender out of the extra tank, and it all came back. It's actually the original one.

Anyway, yes, I have experienced the swwwwiiiissshhhh sound when removing the cap. The valve in the cap is supposed to let air in, but not out, right? I believe I'll go pry back the little tabs and 86 the valve and see what happens. It's so intermittent. Very frustrating. Guess I'll take the 7 year old with me to the river and see if it does it some more.
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post #27 of 34 Old 09-20-2010, 01:05 PM
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I don't believe the cap on these CJ's have any venting built into them. That is why I asked you the question.

The venting is done from the 2 rollover/check valves that are on top of your tank. They y into a single line which goes up to your charcoal canister to vent the gas tank. If this line is stopped up, you will get the symptoms you were describing.

The next time your problem happens, open the gas tank cap and see if the problem goes away. If it does, you have a gas tank venting problem.
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post #28 of 34 Old 09-20-2010, 01:13 PM
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Thanks, Scrapman! I will.

My cap has a valve in it. Guess I should say had, now. I was a safety inspector years ago, when we had them here. It was one of the things we checked on the list. Anyway, and this sounds pretty stupid to do, but if you put the valve to your lips, you should be able to suck, but not blow. My cap took a lot to suck. A lot of resistance. Better go find me some new check valves.
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post #29 of 34 Old 09-20-2010, 02:24 PM
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I just re-read your first post where you say you dropped the gas tank and replaced the lines. It is very easy to crimp the lines in between the body and the top of the tank.

When I dropped mine, I thought i was very careful to route the lines. I drove it about 5 miles and back, parked it, and it would not start again. No fuel in carb. I took the line off of the fuel pump coming from the tank, and tried to blow air back through it with my mouth. The line was crimped closed.

I loosened all the bolts holding the tank as far as I could, and tried blowing again. I easily blew through the line this time. Got a flashlight and pushed the lines around on top of the tank until I could tighten it up with no crimped lines.

Might be something to check.
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post #30 of 34 Old 09-20-2010, 07:45 PM
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I had the "out of fuel" problem when it was not out. Worked for months to find it. Turned out to be many things and the older CJs are seeming to have the problem.

To avoid a lot of explanation here, I will relate you to another thread that covers most of it. Problem may not be what you think.

http://www.jeepforum.com/forum/f8/cj...-fuel-1101974/

That link pertains to a 78 CJ, yours is a little newer, so the lines may not be as old, but the other factors could be the problem.

There are some other threads that address the problem as well if you want to search it.
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