okay....I've searched and searched. Nada. Here's what I currently have installed. No changing things. I wanna drive it! ProComp electric fuel pump mounted on the frame right by the tank 3/8 line to original steel line. Steel line to filter to Holley regulator Regulator to my "odd-ball" carb.....we'll discuss that PITA later. I want to run a return line with just the setup I have. Is it possible? I realize that a return line from the other port on my FPR will steal fuel from my carb.....but if the line is considerably smaller.....say 3/16....won't that still allow enough gas to get to my carb? will gas flow like electricity and "find the path of least resistance"? if not...what about some sort of spring loaded swing style check valve ..... or even a pressure relief valve? Just to add a bit more resistance until the carb just cant take anymore? thanks ahead of time guys. Stu
What kind of regulator are you running? Some of them are already setup to handle a return line such as this one from Mallory: http://static.summitracing.com/global/images/instructions/maa-4309.pdf With this setup fuel is only returned to the tank when the pump is providing more than the carb needs, such as part throttle driving. Devon
I think the secret is in the style of regulator. Im not sure the old school regulator you have is the correct one if you want to run a return line. I would think you need a regulator that will bleed off pressure.
Yep, if your current one isn't the return-style, it would be a great upgrade if you really have the need for a return line. The correct regulator will guarantee full fuel flow when the demand is there; your other plan as described would always be bleeding some volume of fuel back to the tank even at high rpm WOT. Devon
I realize now that the FPR I purchased is not what I needed......but I have it. it's a Holley 1 in 2 out adjustable regulator. I'm just trying to keep this a SUPER budget build. trying to work with what I have. Is what i'm attempthing possible? Or do I now own a FPR I can't use?
No, it's possible but you will have the limitations I described above, making the setup much less than ideal for the amount of effort you're going to go through. I would either stay with the current setup and forget about a return line, or make the upgrade with the right part for best functionality. Keep an eye open for a good used return-style regulator for a cost savings. Watch ebay, racingjunk.com, etc., post in "parts wanted" here on V8Buick. Devon
http://www.fordmuscleforums.com/mustang-pages-1965-1973/492450-holley-blue-regulator-12-803-a.html the second post here claims that the 12-803 has an internal bypass. I just want to be as easy on my pump as possible!
The standard 12-803 regulator will attempt to dead head the pump during low demand operation, so the pump's internal pressure relief valve will open, keeping the electric motor from stalling. Using the correct return-type regulator takes that task away from the pump. For what it's worth, many folks do not run a return line and get good life out of the pump. Devon
just thought of this..... my fuel pump is a ProComp and has different springs to set the running psi. based on that fact....does this mean it has a bypass mode?
Yes, it's the same internal pressure relief valve I mentioned earlier. Some are fixed, some can be adjusted like yours. To know what's really happening with fuel pressure at the carb though, you'll need to plumb a gage near the inlet and see what's happening at max demand, which is high rpm at wide open throttle, like a max effort down the quarter mile. Devon
