Holley Fuel Regulator not adjusting

[03BlkZ]

Hello I just installed a new Holley 12-840 fuel press reg on my 70 C10 with a 350. I am running a summit carb and it is needing around 5 psi of fuel pressure. My Delco mechanical pump is putting out 9 psi So I installed a regulator. Problem is that it is not adjusting properly. Initially it was reading 6.5 psi. I tried to lower it a little and nothing happened. I drove it for about 20 minutes and then the pressure showed 2 psi. I tried to bring it back up and nothing happened no matter how far I adjusted it. I shut it off and let it sit for about 30 minutes the restarted and it was a 5.5. Anyone else experience this? I feel like I remember reading something about holley having a ball valve issue maybe. I don't know.
Thanks,
Brent

[HO455]

I would take it apart and inspect it for debris and smooth operation. It sounds like you may have debris in the fuel lines.

[Guy67UK]

Also get your gauge checked, if you are using a fluid filled gauge the readings can be affected by heat from the motor, headers etc which could be why after leaving the vehicle for 20 minutes changed the reading..

[dmjlambert]

The behavior you describe of the regulator makes me wonder if the pressure adjustment should be made with no pressure in the system, adjust part of a turn then start up and test the pressure, repeat. The manual doesn't mention that, but it would not surprise me if it worked that way. It may be worth a try. Others with more experience may know better than me, so if my idea is just wacky you all can just tell me.