fuel return line

how important is the fuel vapor return line on a airconditioned 401. why is it not on the non air cars?
do i even need it?

 

Well, It is very important,,,, and yes , yes, yes, you do need it....
It isnt a vapor return line,,,, it actually is a liquid fuel return line and what it does is to take the fuel in a loop back to the tank.... allowing the tank to be a heat sink and cool fuel arriving up to the front of the car all the time... eliminating vapor lock that would happen if you were driving the car in heavy traffic on a hot day with the air on....
Now , that said, if you are running a car at the strip, and have taken the air off, and are looking for some more fuel pressure,,,, dont use it....

 

i'm keeping the air on the car and will drive on the street alot.
i maay also run up to the race track on a weekend or two.

and i added dual quads. do i still want it?

 

Yep,,,,

 

will i get enough fuel pressure to run both carbs?

 

Donno,,,, if not ,,, install a carter electric fuel pump back at the tank... that will supply plenty...72 gph....no way you will use that much.....:Brow: :Brow:

 

robbmc performance makes high a performance one. i use one nice unit. i have 2x4 and a return line keeps up fine.

 

Does anyones fuel return bang or knock near or at the fuel tank?

I own a 65 Riv. Mine knocks, especially when cold.

If someone has had the same problem, what is the fix?

Thanks,

Marty

 

Agreed.

The ones I've seen use a restriction inside that 1/4" nipple; while liquid fuel does pass through the tube, the restriction is intended to let the fumes (vapor) out without passing too much liquid fuel.

Since fuel use is based on horsepower created, it doesn't make any difference HOW MANY carbs you have. Either you have enough pump to provide the fuel needed to generate the horsepower...or you don't.

 

Just a curious thought but has anyone ever tried putting a shut-off valve of some sort on the return line so they can shut it off at the track? Seems like a possible solution but maybe it's just my way of thinking

 

where do i need to run this return line from btw

 

Well , on a 64-65-66 the line runs from a opening in the frame crossmember over on the rt. side if you are standing in front of the car looking under the hood... and it goes thru the frame and comes out and runs along the frame secured by some clips and goes all the way back to the diff hump and then over toward the center of the car.... from there a rubber line hooks up to the tank sending unit...i am sure that some one on the board has a diagram....

 

I have one on mine.its plastic. i did it for the cold weather to get the fuel warmer.i have my exhaust blocked in the intake and with fresh air hood scoop its to cold whens its 40 or 45 out. i didnt turn it off at the track in only lowers the pressure about 1/4 lbs.with a 3/8 fuel line and the hp pump no fuel problems.

 

where does it hook in at the front to the carb or what

 

yep, ''da Wizzard'' is right about it being called a '' vapor return line'', but unless it was going into vapor lock , it would be a fuel return line... actually it is both...
on a nail head there is a double nipple coming out of the inline fuel filter that goes back to that line....

 

ok well im running a electric pump and inline filter so i just need a y at the filter running back to the tank right

 

Look again at Larry's picture,the return fitting is at the pump and at the sending unit/fuel supply fittings on the gas tank.If your pump doesn't have the second port for the return line and your tank has only one hose coming out of it you will need some parts.

If the second fitting at the tank is there but sealed somehow,uncap it and run the line.If you are running an electric pump then you may have to incorporate a regulator with a return line port.Hope that helps.

 

Yep, there is something to what Hector has said about checking the whole system out... I was not having any problems with my fuel supply on my 65 GS when I tore it down... when I started trying to start back up ,, no fuel,,, checked the lines with compressed air,, no air thru them... found 2 different dirt dauber nests built in the lines :Brow: ....dont assume that lines are ok,,, check to see if they are open and intact....:laugh: