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Fuel return line?


dynosoar1

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Hey guys I have a question regarding my fuel return line from my tank. At least I'm assuming that's what it is. It runs from the center of my tank through a flex hose down through a hard line that travels along the underside of the driver side of the car all the way up the frame rail to the front of the car near the grill. I first noticed the issue when the car sat after I drove it and I had a puddle of gasoline near the rear suspension it turned out the cloth covered flex hose had cracked so I replace that with all new fuel line to the Hardline. After driving it again the next day I had no issues until I came out at night and noticed another puddle below my pedal box and gas was leaking along the frame rail. This time I discovered a hole in the Hardline right next to the pedal box, see attached picture. The thing is the next thing I noticed that where that Hardline terminates up near and under the battery shelf near the grill the line just terminates with an open-end? So it would seem that that line is basically doing nothing but allowing gas to escape from my tank. I can cut out the Hardline and the section that is broken and replace with a flex line I suppose but would it be better to just cap off that return line at the tank I'm not really sure if it's even needed for the carbureted car? Hoping someone can advise me on this. Car is a 1973 2002 carbureted 2 Barrel 32 / 36. Photos show tank hard-line under driver side Terminus of the Hardline up under the battery Shelf with no plug or line in it's just open and the hole in the Hardline next to the pedal box

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13 minutes ago, jgerock said:

That is the vapor recovery line that runs under the car. Believe there was a charcoal canister connected to it in the engine bay, then to the carburetor.

 I believe for my year, 73, the charcoal box was in the trunk and vapor line ran from gas inlet (see picture 1) to box in trunk, which is missing (see picture 2).  Unless there were two vapor lines, one from fuel inlet and one from tank. 

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Yup, that’s fuel return line that rusted out. Replace it with same size tubing front to back from your local auto parts store. There are members here will tell you to get rid of it all toghter. Me, like to keep it to original design was intended.

76 2002 Sienabraun

2015 BMW F10

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8 minutes ago, Buckeye said:

Yup, that’s fuel return line that rusted out. Replace it with same size tubing front to back from your local auto parts store. There are members here will tell you to get rid of it all toghter. Me, like to keep it to original design was intended.

Can I just cap this off for now?  And where is it supposed to terminate on the carburetor?  I dont see a spot it would connect to.

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Um, I thought that hard line under the drivers side was the SUPPLY line, and the plastic hose through the passenger compartment was the return line? At least that's how it is in my 74 tii.

 

Are 73 normal 02's different?

1974 2002 Tii-SOLD

1978 911SC Coupe

1988 Landcruiser

2020 M2 CS

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15 minutes ago, NYNick said:

Um, I thought that hard line under the drivers side was the SUPPLY line, and the plastic hose through the passenger compartment was the return line? At least that's how it is in my 74 tii.

 

Are 73 normal 02's different?

Plastic line through passenger compartment is main fuel line.  Its plastic and designed to melt without spewing fuel everywhere in event if fire. 

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27 minutes ago, NYNick said:

At least that's how it is in my 74 tii.

 

The hard line is the supply in a tii and it terminates along the frame rail by the battery, because it has to take 50+ psi fuel pressure.

 

The vent in the trunk went to a plastic vapor recovery tank under the package shelf.

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6 minutes ago, Einspritz said:

 

The hard line is the supply in a tii and it terminates along the frame rail by the battery, because it has to take 50+ psi fuel pressure.

 

The vent in the trunk went to a plastic vapor recovery tank under the package shelf.

Right. Just replaced the entire thing.

1974 2002 Tii-SOLD

1978 911SC Coupe

1988 Landcruiser

2020 M2 CS

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The fuel line showed is a fuel return line originally installed on carburetor models. It had a diversion valve installed originally, not needed with Weber carbs. 

For safety’s sake plug this at the top of the fuel tank. Do not use as a vent line. Big problem with a full tank of gas ️ 

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4 hours ago, DBMW02 said:

The fuel line showed is a fuel return line originally installed on carburetor models. It had a diversion valve installed originally, not needed with Weber carbs. 

For safety’s sake plug this at the top of the fuel tank. Do not use as a vent line. Big problem with a full tank of gas ️ 

Yes I found that out prior to this post.   Just got my Haynes book today and now see what it was.  I was thinking of plugging it off below the car, but you think at the tank is better?  Justvworry that if plug ever failed, trunk gets pumped full of gas, rather than roadway.  What do you recommend for using to plug this?

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My fuel return line rusted through by the pedal box.  I cut that section out and put fuel hose there.

 

The original fuel diverter valve bled-off the fuel pressure once the car was shut down... which is a good thing, imho. 

 

I use a Jeep fuel filter (with two outlets) to serve this purpose; since my valve had been considered 'extra' by a previous owner, who removed it.

 

There is a shit-ton of information on the topic in the archives.

     DISCLAIMER 

I now disagree with some of the timing advice I have given in the past.  I misinterpreted the distributor curves in the Blue Book. 

I've switched from using ported-vacuum to manifold, with better results. 

I apologize for spreading misinformation.  

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12 hours ago, DBMW02 said:

The fuel line showed is a fuel return line originally installed on carburetor models. It had a diversion valve installed originally, not needed with Weber carbs. 

 

You have a couple of options, you can fix what you have left or bypass it completely. You do need to do something, because as is, it will syphon gas when the tank is full, (don't ask me how I know).  Because the hard line has a hole in it at the pedal box, plugging it at the tank is the easy fix.  Just cut the rubber line, stick an appropriate size bolt it and clamp it down.

 

If you wanted to return it to stock you will need to cut out the hole in your hard line or replace it with a new one, buy a return valve (See picture), and connect it between your fuel pump and carb and connect return line to it.  You will also need a vacuum connection to make it work.

 

Mark92131

ReturnValve.jpg

1970 BMW 1600 (Nevada)

 

 

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