HELP.. Too much fuel pressure coming from new regulator

Hello to all, I have recently swamped a Holley 650 DP onto my 306, and havent even started the car yet with the carb and the new fuel system. The OLD fuel system gave me no issues what so ever and consisted of a Holley Red pump (7psi) and 1 single 12-803 regulator and a Carter carb with vacuum secondaries. I changed this to a different system because I want a Holley carb with mech secondaries and Im also install a NX nitrous plate system and they recommend 8-12 psi to the fuel pressure solenoid which is more than the red pump can pump out.....

My new system consists of a Holley Blue pump (14psi) and 2 - 12-803 pressure regulators which are suppose to be adjustable from 4.5 to 9 psi, 9-10 being the limit. The regulators are currently mounted together on a bracket and fed by the same single 3/8" line fromly came from the red pump where the blue pump is now: except the line is split into TWO 3/8 feed lines to the regulators with some brass fittings. I am trying to get the car running well on the carb only first then Im adding the nitrous, SO I have fuel going to the bottom inlet ports on both, and one has both outlet ports on the side blocked off with a plug and the other regulator has one blocked off and one barbed fitting and hose running to the carb.

MY ISSUE IS... That I am getting **14 PSI** out of the regulator with the key on and the pump running..... So I was like well maybe I have A bad regulator, so I swapped the carb fuel line to the other while moving the block off plug back to the suspect one and yet again **14 PSI** on that one also.... W T F....... So then I tried to adjust them while monitoring the pressure with my Snap On gauge to eliminate the Holley gauge and the SnapOn gauge reads 14psi all the time on both of the regulators regardless of where the adjuster is, all the way in or all the way out. THESE ARE BRAND NEW, One came with the Blue pump i bought from Advance Auto, the other was purchased from Jegs.....So then I thought I might have a new Blue pump that is kicking too much pressure and bypassing the diaphragm in the regulator so I tested it and the pump and feed line and found the both to be 14 PSI... REALLY???? By the way the SnapOn gauge is right, reads the same as my Matco gauge, the Holley gauge, and 2 Mr Gasket gauges.... So Iit sounds like I have 2 bad regulators but what are the odds of that.................... THOUGHTS

Anyone have any thoughts or seen this before???????????????

So I ordered another brand new Holley 12-803 regulator and put it in today and same ****, 14 PSI out of the regulator. I know that the pressures are suppose to be adjusted with the engine running but that reg is not suppose to go above 9 PSI and I cannot even begin to run that much to the carb cause it will blow past the needle and seat. What in the HE double L is going on here this makes no sense.

mustangtw5901 said:

I know this thread is a few months old, but I am experiencing a similar issue and wondering if the op got it figured out and what it was? I have a holley black fuel pump with twin holley regulators up front, one feeding a nitrous fuel solenoid and one feeding a holley 600 carb. The regulator feeding the carb is brand new. When I turn the ign on with the fuel pump running, the pressure goes way too high. I'm seeing 14psi+ from both regulators. No matter what adjustments I make, I can't seem to get the pressure down. Are the holley regulators crap or what?

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I went through 6 different new regulators and 2 new pumps and could not resolve the issue.... Holley was no help, one idiot over there even told me to wire in a toggle switch for my fuel pump so it doesnt turn on with the key and blow past the needle and seat before the engine started..... I couldnt believe he said that, I called back and spoke to someone else and told them I was told that and he couldnt believe it. I tried everything I could think of and just got tired of it..... So...I gave up and sold my nitrous, I want a blower anyway. My next step was going to be to buy a Aeromotive regulator. I couldnt get any less than 14 psi regardless where the regulator was set.