I have a Holley red pump with a Holley 4/12 - 9 psi regulator. This regulator is not a bypass style.



When the engine is cold:

The pump outlet pressure is about 8psi The pressure after the regulator is about 5.5psi

When the engine is warmed up:

The outlet pressure of the pump is about 6.5psi. The pressure after the regulator will not go higher than 3psi.

The pump is getting 14 volts.



It's been like this since the engine was started. Last weekend the thing didn't want to idle. I looked at the pressure and it was barely above 0psi. So the problem seems to be progressing.

I'm using the stock tank at the time. I have a 5/16 line from the tank to the fuel filter with a 3/8 line from the filter to the pump and 3/8 hose, -6AN Hose or -6AN tubing after the pump all the way to the carb. I have a 90* elbow on the inlet of the regulator. The only other 90* bend is at the carb inlet. All other bends are about 135*. The filter is one of the MR gasket universal deals with nipples for 1/4, 5/16, and 3/8 hose. The fuel line does not run near any significantly hot spot. I can touch and hold the line without burning myself. It has nothing to do with the fuel level in the tank. The results are the same if the tank is half full or almost empty. I've used different gauges to rule out a faulty gauge.

Does this sound like a bad regulator? I want to have the pressure at 5.5psi because that is what the Edelbrock manual says is most efficient for the carburetor. I realize that the system isn't ideal but I don't understand why I can't get 5.5psi at the carb if I have 6.5 at the pump outlet. I'm not even able to achieve the 4.5psi minimum of the regulator!



I've contacted Holley's e-mail tech support. As someone who provides e-mail and phone tech for vintage BMW motorcycles, I'm not impressed.


Lawrenceville, GA