I want to add a fuel return line to my weber 32/36 on my 77 20r, ive heard about the benefits. But I dont want to return the gas all the way back to the tank. Im wondering if this idea would work, ive got a aftermarket electric fuel pump mounted under the hood(I know its the worng spot but it works for now). So if you look under my hood, you can see the fuel line run up into the engine bay, it goes into a fuel filter, then into the fuel pump, then into the carb. If I was to add a line on the return side of the carb, and instead of going to the tank, just circle it back around and splice it into the main fuel line between the pump and filter. So it wouldnt go thru the filter twice. But when the system was "full of gas" it would just circulate around and when the system "needed more gas" it would draw from the tank as needed to keep the system "full".

 

I don't think that would work.

If the carburetor needed more fuel, it just wouldn't pass as much to the return port to begin with. The return line would need to go back to the fuel tank to deal with the excess fuel, otherwise the return line wouldn't really be returning to anything.

Sorry, I don't know what I am talking about......

 

The fuel pump is rated at 3-4 psi I think, which is good for a weber. But having the fuel line dead end at the carb could be bad because the fuel pump is always running. What would happen if I turned on the fuel pump and pinched the line at the carb? The pump would continue to run. Would the pressure increase over 3psi? Would it reach 3psi and then what happens inside the pump? Would the pump break eventually?

 

You carb is not continuously fed gas by the fuel pump, depending on conditions. It has a needle valve connected to a float and this valve closes when the fuel bowl is filled to the proper level. As the engine runs & uses the gas, the level drops, the float drops with it, and opens the needle valve, allowing gas to flow in. Even at cruising speed (4th or 5th gear) the needle valve isn't always open.

Second, electric fuel pumps almost always have a built-in relief valve, so there really isn't any way your fuel supply line to the carb is going to exceed the rated pressure of the pump.

Return Lines - The Weber 32/36 usually does NOT have a return line, or even a fitting in it for one. The stock Toyota return line system is actually a fuel VAPOR return line, NOT a LIQUID fuel return line. The return line coming off the stock Aisin carb goes to the charcoal canister, with another line off the canister to the metal return line to the tank. Toyota designed it this way to catch & trap fuel VAPORS from getting into the atmosphere. The Charcoal canister was never designed to deal with liquid fuel from the return line. If for some reason the carb developed a stuck-closed needle valve & the carb would flood, liquid fuel would flow thru the return line into the canister & basically ruin it.

People have been running the Weber 32/36 on 20R's for years with an aftermarket electric pump & never had any problems, despite the lack of a return line. You don't need one in this setup. However you should get that fuel pump moved back near the tank if you are concerned with pump life. Underhood temps can exceed 200F and heat will not do the pump much good. It will also work better not having to "draw" gas so far up the feed line, but instead "push" it up the line from the tank. Most electric pumps are designed to work best that way.

 

I guess a good question is what are the "benefits" you've heard about? From the first sentence of the first post.

There's an issue of Webers flooding in extreme off-level situations where a stock carb has an advantage, but otherwise I'm not sure of other benefits.

 

https://www.yotatech.com/forums/f114...n-hurt-248772/

Im not a weber guy but this thread has a very similar discussion