Holley HP125 Fuel Pump Problems

[REVIN KEVIN]

Hey. I have a Holley HP125 fuel pump with a 100 micron pre and a 40 micron post filter 1/2” fuel system with a billet regulator, pump relay kit,and a 1/2” tube sending unit in my 1976 Chevrolet Laguna S3 with a 496 BBC and Holley 950 HP carb. I finally got the car started for the first time a couple of weeks ago. Huge moment for sure after a 7 year build. I did get it started but it only had 2-3 psi and I had to turn it off because it only had open headers at that point. Now that sounded great in my garage but I digress. Now that my 3” oval X-Pipe exhaust is installed, I tried to start it again but no fuel pressure at all. I took the pump apart and it was clean so I put it back in. One of the three bolts on the bottom was loose from Holley but I corrected that. I ran the input hose into a gas can and put the carburetor hose into a cup to check flow. It only pumped a little fuel and then, no more. You can still hear the pump running but it’s not loading up and pumping. Wow, I just said a lot. So my question is, has anyone run this pump and have you had a similar problem? And yes, I do have this question into Holley but they have yet to answer. I have the pump mounted below the tank but the problem is it won’t pull fuel up from the 1/2” sending unit. I just got out from under the car. I took the input of the pump into a container of gas with a custom line that I made and opened up the fuel line to the carburetor. I ran that into a cup in the front. This means that I would be testing the entire line to the front through the regulator. When I did that I filled the about 32 oz cup in the front in about 5 seconds. So, I then connected the rear back to the tank and connected the carburetor back up. No pressure. You can tell that the pump wasn’t trying to load up. I then took the carburetor fitting off and tried again. No flow whatsoever. That tells me that the pump can’t pull from the tank. After I rest my old back I am going to drop the tank and see what could be wrong there. Thanks.