Fuel Regulator not holding pressure

[scott2683]

When I bought my duster it had a Tanks Inc. tank and pump, so I don't have the specifics of the pump. it's ran to a holley 12-841 pressure regulator (with return), and then to an edelbrock 750 CFM carb on a 360 magnum engine.

The car had been running really well with no carb issues. I got it out a couple days ago, and it started developing an issue where it would die or bog badly every time I hit the gas and I could smell raw fuel. It would fire right back up, and I would have to get the RPM's up in order to overcome the hesitation.

I'm under the hood checking everything out and I notice that the gauge on the regulator says it's at 9 pounds. Seems a little high, so I do some googling, find out that edelbrock recommends 5.5, so I adjust it down, and BOOM .... hesitation is gone, and the cars idling better too. I continue to let the car run for a few more minutes, and within 5 minutes it's right back to 9 pounds again. I don't think it's an issue with my return line being too small, I'm running 3/8" fuel line.

So I'm trying to decide what my best option here is. I've read reviews on the holley 12-841, and it seems a few people have issues with them and can't get them to adjust.
Should I buy a rebuild kit and see if that fixes the issue or should I just invest in a better pressure regulator that can handle more pressure? Does anyone have any ideas on what the cause could be? I've always had a mechanical fuel pump on my mopars so I'm not sure what my best course of action would be.

 

[devilchicken]

I have the same basic setup you have and I went with a Aeromotive pressure regulator for mine and so far had no problems and I looked on tanks inc and this is what they had to say on the subject of in tank pumps and carbs, It looks like you might need to see what pump you have in the tank as it might be too much for a carb, hope this helps


It is becoming more and more common for people to use an in-tank electric pump to feed a carbureted engine. Many new engines simply do not have the provisions to use a mechanical fuel pump. Sometimes there is no room to have a mechanical fuel pump in the engine compartment. Others simply want to clean up the look under the hood and do so by removing the mechanical fuel pump.

Any of our in-tank pumps can feed a carbureted engine provided that a bypass regulator is used. Because an EFI fuel pump can produce a large amount of flow, a bypass regulator is necessary in order to return the excess fuel back to the fuel tank. When shopping for a bypass regulator make sure that you buy one that is specific for carbureted applications. This is because most carburetors only require around 6 psi to operate. Typical EFI bypass regulators run between 40-80 psi while most carbureted bypass regulators are adjustable from 4-10 psi. Keep in mind that since the pressure requirements of a carbureted application is lower that an EFI application the flow rate of your pump will be higher. This means that the fuel pump is capable of supporting higher horsepower. For most applications our TBI or 2 series fuel pumps provide enough flow for a carbureted engine.

 

[scott2683]

Thanks for the reply and the insight. I have read a lot of good stuff about Aeromotive pressure regulators. That may be the route I go with this setup. I need something dependable.

 

[toolmanmike]

Sounds like the Aeromotive regulator is built for the job. The Holley regs were designed to regulate low pressure like what the Holley red pump puts out. 7 psi. It's easy for a regulator to do it's job when the input pressure is only a few pounds of the output pressure. Go with the Aero.

 

[diymirage]

what size fuel and return line?

i have heard that if the return is smaller it may not handle the volume of fuel being send back, causing pressure to spike

 

[scott2683]

That's what I've read too but it has 3/8" fuel line. I'd think that should be plenty.