Fuel Line Question 5/16 to 3/8

[mkcharger]

My fuel sending unit is bad and I am looking at switching over to a 3/8 unit from a 5/16. My old unit has only one line to it and I noticed that the 3/8 has two lines. Could someone please give me a description of how the return line is run, does it connect to this extra line on the 3/8 sending unit, and how does the vent on the filler tube connect in. Thanks

[mkcharger]

thanks

[cudaken]

 Must be a vent or maybe if a new Mopar (To me anything after 70 is a newer Mopar) to the charcoal canster. But they where in the engine compartment I believe. Never had one, all my Mopar's ar 70's and older.

                       Cuda Ken

[derailed]

The 5/16 return line ran from the sending unit up to a charcoal canister attached to the motor on my 68. Right now i have the return line plugged off because i dont have a canister. The vent on the filler tube just runs from the top of the tube down through a grommet and into the trunk floor

[8WHEELER]

Here is the picture again of the vapor separator for 68-70 440 HP and Hemi cars bolted to the fuel pump.
You do not need a return line if you are just upgrading to 3/8 line. They sell 3/8 sending with only the
one 3/8 outlets I have got one off ebay and I think YO and others sell them as well.

Dan

[Just 6T9 CHGR]

Originally on an HP big block car the main line from the tank to the pump is 3/8"....out ot the pump to the vapor seperator gets cut down to 5/16" as well to the carb.

The return line back to the tank from the seperator is 1/4" in diameter.....it runs parallel to the main line

[mkcharger]

Thanks for all the responses. I just need a little clarification to the vent on the filler tube. Am I right in saying that it is not connected to anything and just runs through the trunk floor.

[Just 6T9 CHGR]

Yes the vent tube on the filler neck is not connected to anything.   The return line is connected to the sending unit on the tank.

[Tom_440]

The vent tube is connected to the filler, runs through the trunk pan, and into the frame rail (where it "vents" into your garage)

[Shakey]

Originally on an HP big block car the main line from the tank to the pump is 3/8"....out ot the pump to the vapor seperator gets cut down to 5/16" as well to the carb.

The return line back to the tank from the seperator is 1/4" in diameter.....it runs parallel to the main line

Waking sleeping dogs here but....

How is the line cut down from 3/8 to 5/16 at the fuel pump?

[Just 6T9 CHGR]

Excuse the worm clamps

[AmadeusCharger500]

What is the purpose of the vapor separator?
What will happen if the return is just blocked off.
Was the separator used on all cars?
Will the unit for the late 60's cars work for the early 70's cars?

[Just 6T9 CHGR]

What is the purpose of the vapor separator?
What will happen if the return is just blocked off.
Was the separator used on all cars?
Will the unit for the late 60's cars work for the early 70's cars?

Straight from the FSM.....

[firefighter3931]

Excuse the worm clamps

Oh, the horror   

Ron

[Just 6T9 CHGR]

Excuse the worm clamps

Oh, the horror

Ron

Did ya notice the correct one on the 3/8" line to the pump though?? 

[firefighter3931]

Did ya notice the correct one on the 3/8" line to the pump though?? 

Yep, looks "correct"   

Ron

[Shakey]

Excuse the worm clamps

I figured the pricey KV hose made up for the gear clamps.

[Just 6T9 CHGR]

You wouldnt believe how much "wite-out" I had to use to do that

[ChargerRob]

Chris, Where is your fuel filter located/mounted. Do you have a pic?

Thanks, Robert

[8WHEELER]

Chris, Where is your fuel filter located/mounted. Do you have a pic?

Thanks, Robert

The fuel vapor separator is a fuel filter. I run an extra mopar fuel filter 4in before the fuel pump. The main
reason I run another fuel filter is so if the fuel vapor separator '' fuel filter '' gets clogged it will cost about
$65.00 to replace. So I run a fuel filter just before the pump to save money, better filter and save time.

Dan

[ChargerRob]

Thanks, Dan