Dual Carb with fuel return line Options

[bbrock]

Unless the tanks differ, the part in the center is a baffle, not a reservoir (note the holes in the side).

Further, the tank pulls (finger filter) and returns (the other hole) within this baffle.

This photo was a result of my pouring in some Stabil without ensuring the paper disc was removed from the mouth of the bottle. I was quite unpleased (I got it out with a flexible grabber).

Yes, it is a very well engineered reservoir. The pump is constantly scavenging fuel from inside the reservoir and dumping it back in which will serve to keep the supply line submerged. The holes are needed to allow the full tank to be used. Without them, the supply line would start sucking air as soon as the fuel dropped below the lip of the bowl. I've actually watched mine with a low tank and pump running and it does indeed keep the level inside the bowl higher than outside. Don't know if it still works with low pressure carb pumps since it depends on return fuel being added faster than it drains through the holes.

[ndfrigi]

Ok I'm an idiot what is the key to the diagrams ( the circle the rectangle and the square with the triangle)

1. Big Rectangle : fuel tank
2. Small rectangle : fuel filter
3. small round : fuel pump
4. pentagon shape : fuel regulator
5. then Carbs

I think that is what I understand.

[Front yard mechanic]

Ok I'm an idiot what is the key to the diagrams ( the circle the rectangle and the square with the triangle)

1. Big Rectangle : fuel tank
2. Small rectangle : fuel filter
3. small round : fuel pump
4. pentagon shape : fuel regulator
5. then Carbs

I think that is what I understand.

Thanks makes sense now . I'll try B. My regulator does not have a return port

[bbrock]

The Webers (and Dells) do not offer an in/out port. Therefore, it will be "teed" outside the carbs.

I was also curious about what Mark offered: where did you find a pressure regulator that will knock the stock EFI pump down to 3-4 psi? I'd suggest much more system pressure than that and you risking over-riding the float/needle valve.

I run single-line on the race car with Dells.

I'm running this Malpassi bypass regulator. So far it has worked perfectly holding the pressure at the carb at a steady 3.5 psi. It has been so steady, that I finally pulled the pressure gauge after monitoring pressure for 3K miles without seeing any variation in pressure at all. I'm running SS lines.

The important key is using a bypass regulator that bleeds off enough volume of fuel from the supply to maintain pressure rather than choke down pressure like in a typical dead end regulator. I almost went the PMO route because it is supposed to do the same thing, but now glad I didn't after reading Mark's post.

[nathanxnathan]

I'm running this Malpassi bypass regulator. So far it has worked perfectly holding the pressure at the carb at a steady 3.5 psi. It has been so steady, that I finally pulled the pressure gauge after monitoring pressure for 3K miles without seeing any variation in pressure at all. I'm running SS lines.

The important key is using a bypass regulator that bleeds off enough volume of fuel from the supply to maintain pressure rather than choke down pressure like in a typical dead end regulator. I almost went the PMO route because it is supposed to do the same thing, but now glad I didn't after reading Mark's post.

Are you using the "boost reference" port or just plug it and it works as just a regulator with a bypass?

[NARP74]

Same question for @BBrock and which configuration are you using?

[slivel]

My configuration is:

1. Tank
2. Filter
3. Pump
4. Bypass regulator
5. Low pressure regulator
6. Carbs

I have a Holley Blue high-volume pump followed by this bypass regulator:
https://www.holley.com/products/fuel_system.../parts/12-803BP
The bypass ranges between 4-9 psi which is too high for my Webers so I have a low pressure regulator in the engine compartment. I'm using this one:
https://www.holley.com/products/fuel_system...rs/parts/12-804
My bypass line is in the frunk and dumps into the tank. This was to keep cool fuel flowing through the high-volume pump which would get hot during idle or low flow part throttle settings.

[bbrock]

I'm running this Malpassi bypass regulator. So far it has worked perfectly holding the pressure at the carb at a steady 3.5 psi. It has been so steady, that I finally pulled the pressure gauge after monitoring pressure for 3K miles without seeing any variation in pressure at all. I'm running SS lines.

The important key is using a bypass regulator that bleeds off enough volume of fuel from the supply to maintain pressure rather than choke down pressure like in a typical dead end regulator. I almost went the PMO route because it is supposed to do the same thing, but now glad I didn't after reading Mark's post.

Are you using the "boost reference" port or just plug it and it works as just a regulator with a bypass?

I just left the "boost reference" port open. I believe that is what the instructions specified if it wasn't being used. And yes, it works just as a bypass regulator in that configuration.

Same question for @BBrock and which configuration are you using?

I believe I'm using option C, but it might be D with a Tee just after the regulator output. I'll check tomorrow and confirm.

[bbrock]

Same question for @BBrock and which configuration are you using?

I believe I'm using option C, but it might be D with a Tee just after the regulator output. I'll check tomorrow and confirm.

Forgot to check yesterday but I'm using option D. I like C better but didn't have the fitting to run through the 3-4 carb so I could eliminate the Tee (actually a wye in my case).