gas coming back out of the tank from the sending unit return line - JeepForum.com
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Unread 07-10-2010, 06:48 PM   #1
cableguy55
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gas coming back out of the tank from the sending unit return line

I have a 79 CJ7 355 SBC all emissions stuff yanked off. After driving a distance of filling the tank i have a ton of gas coming back out of the tank from the sending unit return line. Tried unscrewing the cap to relieve pressure but that doesn't help. The SBC has a mechanical fuel pump also. and when i mean it comes out the return line it sounds like somebody turned on the water hose behind my jeep/(Heep right now ;p

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Unread 07-10-2010, 10:18 PM   #2
wrongway92407
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Maybe I'm missing something but the return line should be connected to the tank! You need to explain how your lines are connected.
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86 CJ7 2.5 detroits, OBA 4.56, air tank bumpers, w/D rings,9500I warn 31x10.5x15, Trxus
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Unread 07-11-2010, 12:59 PM   #3
1986cj
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What is the return line hooked to now, carb side, tank side?
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Unread 07-11-2010, 03:58 PM   #4
Matt_G
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are you using a filter? make sure your filter is hooked up right.
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Unread 07-12-2010, 08:52 AM   #5
cableguy55
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Ok out of the top of the sending unit there is two lines coming out. One is the gas feed and i am assuming the other was a return line that went to the canister. the non feed line is the one that the gas is coming out of. my fuel pump has no return line hook up.
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Unread 07-12-2010, 09:21 AM   #6
1986cj
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Get yourself a Jeep inline fuel filter. The feed line and return line go to it and the other end to your carb.Any excess fuel will be sent back to the tank from there. Part Detail at CSK Auto
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Unread 07-12-2010, 09:24 AM   #7
scrapman
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Are your vent lines hooked up? The tube you are talking about connects to the top of the sending unit an does not go down into the tank far at all if I remember correctly.

So your gas is flowing out of this line from pressure building in the tank, or from the jeep being on an angle enough to let it flow out.

If your vent lines are working, just plug this line. If they are not, you need to get them working.
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Unread 07-12-2010, 09:37 AM   #8
cableguy55
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does the tank vent out the cap?
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Unread 07-12-2010, 09:40 AM   #9
82JeepCJ7
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You could always run this line up high with a filter on it as an aux vent to help prevent vapor lock in the future.
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Unread 07-12-2010, 09:47 AM   #10
scrapman
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Quote:
Originally Posted by cableguy55 View Post
does the tank vent out the cap?
No, it should have a vent line which leads to a roll over check valve behind the drivers side rear fender, and then on the the charcoal canister located up behind the drivers side front fender.
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Unread 07-12-2010, 09:48 AM   #11
cableguy55
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All of that is gone no longer there.
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Unread 07-12-2010, 09:54 AM   #12
82JeepCJ7
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Get a inline roll over valve (Make sure you put it in with the correct side up ) and run the line to a higher spot with a filter on the end. That will duplicate what came from the factory.
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Unread 07-12-2010, 11:20 AM   #13
1986cj
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You are talking about the two lines from the sending unit right? They have nothing to do with venting the tank. One is the fuel outlet line to the fuel pump and the smaller one is the fuel return line from the fuel filter. It is a simple filter get one and put it in the line. On the tank left side you have two nips on the tank (not the ones in the sending unit) that vent the tank. The two lines go to the liquid check valve and one leaves it and runs up to the rollover check valve. This line leaves the rollover valve and runs up to the charcoal canister. These two are the fuel tank vapor vent lines. No the cap does not vent the tank. I failed emissions for a leaking cap and had to go get a new cap to pass. This is from the 1979 Jeep factory service manual.
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Unread 07-12-2010, 11:47 AM   #14
CSP
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Quote:
Originally Posted by 1986cj View Post
You are talking about the two lines from the sending unit right? They have nothing to do with venting the tank. One is the fuel outlet line to the fuel pump and the smaller one is the fuel return line from the fuel filter.
This is the correct.
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Unread 07-12-2010, 06:42 PM   #15
wrongway92407
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&9-81 has 2 hose connections of the sending unit the large one is the outlet goes to the fuel pump. the smaller one is the fuel return line comes from your fuel filter. The jeep fuel filters have one inlet from the fuel pump and 2 outlets, one to the carb and other back to the tank. There are 2 vacuum lines on the left side of the tank those lines go to a liquid check valve one line comes out of the LCV and goes to a rollover check valve and from the rollover valve up to the canister. there valves are located on left rear on the panel that separates the wheel opening from the rear of the body. Those valves may or may not be connected or the lines are rotten if the valves are free and in working order hook then back up, they're supposed to fuel flow in case of a rollover
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My fleet:
86 CJ7 5.7 vortec. 4L60,D44's,OBA,Air tank bumpers w/D rings detroits,4.88,35" bfg, mt's 9500ti warn
86 CJ7 2.5 detroits, OBA 4.56, air tank bumpers, w/D rings,9500I warn 31x10.5x15, Trxus
86 CJ7 bone stock, w/factory 44 never seen the dirt soon to be for sale
87 Wrangler also never seen the dirt.
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