44 IDF conversation, return line mandatory?

[MIGHTY 8]

Hello,

I’m aware of reasons why some installations decide on returning the fuel back to the tank, but I wanted to see what is the general consensus with those here?

Particularly since my car was FI OEM, versus stock carburetor from the factory.

Thank you,

[SteinOnkel]

I have built dual carb setups without a return line. However, this depends heavily on the rest of the setup. Particularly what sort of pump is used, if there is a fuel pressure regulator and where the lines go in relation to hot engine parts. This vehicle was in Germany where fuel quality is generally much higher than say for example on the West Coast. This is critical because if you are not running a return line the fuel can begin to boil causing vapor lock.

Your car should already be plumbed for a return line so I would suggest using that. Also, I have found that the stock fuel filter from a 70's Jeep Grand Cherokee has a built in pressure regulator and a return line fitting. It is readily available off the shelf and costs about $5. My Weber 32ADFA on my spider seems to love it, it puts out exactly 3.5psi. Whereas the brand new fuel pump was more like 6 psi and would overwhelm the float at idle. I have not used it on a dual carb setup yet.

[zonker]

I have built dual carb setups without a return line. However, this depends heavily on the rest of the setup. Particularly what sort of pump is used, if there is a fuel pressure regulator and where the lines go in relation to hot engine parts. This vehicle was in Germany where fuel quality is generally much higher than say for example on the West Coast. This is critical because if you are not running a return line the fuel can begin to boil causing vapor lock.

Your car should already be plumbed for a return line so I would suggest using that. Also, I have found that the stock fuel filter from a 70's Jeep Grand Cherokee has a built in pressure regulator and a return line fitting. It is readily available off the shelf and costs about $5. My Weber 32ADFA on my spider seems to love it, it puts out exactly 3.5psi. Whereas the brand new fuel pump was more like 6 psi and would overwhelm the float at idle. I have not used it on a dual carb setup yet.

I recommend keeping the fuel return line as well. Did the same setup on my single carb spider, used a 2.2 Dodge Omni fuel filter with return line with the oem inline one way valve. Works great.

[MIGHTY 8]

Thank you,

I had a return line once it was converted and it ran fine. Then I ran into several problems which were readily resolved by deleting the return, and it ran fine.

I have once again reverted to using a return line which was running fine again. However, I have now a renewed issue (stuttering, uneven acceleration) which I thought I could troubleshoot by.....once again bypassing the return.

I shall attempt to try other solutions and keep the return line as it seems recommended to,do so.

[Nut124]

I have been running dual carbs for 20 years w/o the return line. I use an electronic fuel pump and an adjustable requlator in the trunk. Fuel pressure at carbs must not exceed about 3.5 PSI.