1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Keep or block off fuel return. Weber 48ida, Carter 4070, Holley fpr

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Old Nov 6, 2011 | 11:14 PM
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Keep or block off fuel return. Weber 48ida, Carter 4070, Holley fpr

I was reading some of you guys block off the fuel return line...and I'm trying to figure out a few things

I am unsure if the fuel cut/check valves are on the return line or not....I see 2 boxes attached to the fuel line. One mounted to the floor in front of the gas tank, and the other mounted close to where the stock fuel pump was (im not thinking of the fuel filter)

I want to know why its beneficial to have no return line at all.

I have no fuel pressure guage but plan on installing one. Where on the Holley fpr can I mount it? Would that be the return line, and is that how you guys block it?


Thanks
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Old Nov 7, 2011 | 09:22 PM
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First you have to make sure you have a return style regulator, not all are. There will be a specific spot to hook up the return if so equipped.

The pressure gauge can mount to any of the other positions that are available.

A return is beneficial with certain pumps to keep them operating cool. It also keeps a more constant pressure when you quickly mash the throttle or let off rapidly.

If you don't use the return you don't have to do anything with it, just plug it.
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Old Nov 7, 2011 | 11:18 PM
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I have a return style regulator...At least there are 3 hoses coming off it. So are the cut/check valves on the return? Can anyone tell me that? I'm wondering why in Kenestu's thread about installing the Carter 4070, people were talking about blocking the return.
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Old Nov 8, 2011 | 06:48 AM
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Doesn't matter how many ports are available on the FPR. That does not determine wheather or not it is a return style. You better google your model and look to see if it is or not.

The return line has only one valve on it. Right after it leaves the carburator it has a one way valve on it. Blow through it to see which way it flows.

To block the return just turn that valve the other way.

The other valves you mention are all on the feed.
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Old Nov 8, 2011 | 03:17 PM
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thank you. so the valves on the feed...are they necessary?

and i will take a closer look at my fpr and see.

thanks again
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Old Nov 8, 2011 | 07:54 PM
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Running a return line makes the fuel pump run quieter, cooler and last longer. It also cools the fuel as unused fuel is pushed from the hot engine compartment back to the cool fuel tank.

Aren't the check valves in case the car flips on it's lid?
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Old Nov 8, 2011 | 08:11 PM
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I've got a stock nikki carb with no return, my motor came with it blocked, why would that be?
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Old Nov 10, 2011 | 07:39 PM
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Check and cut valves release excess pressure or vacuum in the fuel tank and, like DriveFast7 said, to stop fuel flow in case the vehicle is overturned. (Chapter 4 Fuel & Emissions)
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