How do we set up the return line for our cars?

[QWKDTSN]

I have no idea how this is supposed to work. All right, with a 4bbl Holley with a dual-inlet fuel line, where's the return? I'm using a Holley Blue with the regulator. Does one side of the regulator go to the carb and the other back to the tank as the return, or what? My fuel cell has an inlet for the return but there's nothing in my instructions for the carb or the fuel pump about return lines. It must have a return because the carb can't be fed with a constant amount of fuel all the time. Help!

[72zcar]

Hey, whats happening.

Do i need a return line?

I am also running the holly blue with a regulator. I blocked off the second outlet from the regulator and ran a single line to the carb.

 

I am not running a return line... am i doing this wrong? It seems to run good, but does seem over fueled. After a hard rip up the street at idle there is a little black smoke. Is this because there is no return line?

 

250 lb coilovers and shocks on all four corners from ground control are done, no test drive yet for the springs but it looks good sitting there and does seem happier.

 

http://www.72zcar.50megs.com/ old pics before the tires and coilovers, new pics after sunday.

[ZROSSA]

I may be a bit off becuase i dont know anything about holleys,BUT..... I have never seen a carbed car with a fuel return line. Thats why they run low pressure fuel pumps.

 

Douglas

[blueovalz]

Carbs guys are fine with a single line. You can use a second line from a regulator at the carb back to the tank if you want to go to that much trouble (and with the correct regulator). I've never ran a return line on a carbed motor though.

[John Scott]

You can get away with no return line. The preferred method is having a return. This way you always have a constant pressure at the carb, a constant supply of fresh fuel, and your fuel pump runs with less effort, only when its needed instead of constantly pushing against a dea head style regulator. You'll need a return style regulator, and usually a line that equals the pressure side or larger to return. I use the 1/2" fitting on the drivers side of my fuel tank for return The Mallory site has a good article on this. www.centuryperformance.com/fuel.asp

JS

[Guest Anonymous]

Just for the sake of putting in my .02, If I recall correctly, most, if not all of the early 80's japanese cars had carbs AND return lines. Makes for a more consistant fuel supply/pressure.

FWIW

Larry

[Guest Anonymous]

Ummm, the early Z was a carb'ed car, and unless I'm horribly mistaken (entirely possible), I have a plugged off return line that was original (or was this a vapor line, it came from the SU's)? It may not be big enough, but there is also the Moroso (I think it was them) kit that goes up by the gas fill door and the return line dumps in up there in the pipe section between the fill and the tank.

 

Regards,

 

Lone

[Guest Anonymous]

I'm having an over-fuel problem with my Zcar V8 conversion as well. I installed a fuel pressure regulator, but it looks like I got a defective one. No matter what, the adjustment will not lower the pressure to 5.5, which is what the carb requires. I bought another 'deadhead' type of regulator and am waiting for it to arrive. Looks like I should have gotten the return line type. It's more expensive and more trouble to install, but I think it would cure my flooding problems. The pressure at the carb is now at 12, way too high!

[Guest gprix1]

Just a thought here. I'm thinking it would be fairly easy to fab a short piece of metal tubing with a fitting for the return line brazed or welded on in the middle. Then splice it into the filler hose at a location that is at least an inch or two above the highest point of the gas tank.