Results 1 to 3 of 3

Thread: Fuel Pressure Drop

  1. #1

    Default Fuel Pressure Drop

    I have a dual quad Terminator Stealth system being fed by a Holley 340 log in tank pump though -10AN PTFE line and a 10 micron post filter (PN 162-570). Return is from a 12-845 regulator through -8AN back to the tank.The tank is vented.

    Here's the scenario: I set the pressure to 43 psi while the car is running and keep an eye on it through the handheld that is being fed fuel pressure info through a sensor placed on the fuel feed log on one throttle body. Pressure is fine for about 20-30 minutes, but then fall. When the pressure reaches about 32 psi, I adjust it up again to 45 psi and pressure immediatly begins to fall; about another 10 psi over about 20 minutes of running time. Do you think the pump is failing? Are there any other potential causes?

  2. #2
    Join Date
    Feb 2018


    Take a look at this thread: I was having somewhat similar issues and have since resolved the issue. Also, I'm assuming you're using the the higher pressure version of that regulator or have changed the spring. Having changed a few components in stages and observing the results, I personally think that not using the Holley dead-end style fuel supply and plumping it similar to a fuel rail installation is the way to go. Although there are obviously many users running the out of the box fuel supply with no issues.

  3. #3


    Thanks for responding. Yes, I'm running the EFI spring in the regulator. At this point, I've solved most of the pressure drop issues. Part of it was a restrictive (too small, too many bends) return line; 6 psi of pressure to return it to the tank. The other issue was that the diaphragm was upside down. After fixing that and replacing the lines, most of the issue went away, but I was getting about an 8-10 psi drop under demand. I installed a 450 LPH pump to replace the 340 LPH pump; which had borderline capacity for my setup. Only issue I have now is that I can see a 2-3 psi drop when the pump has demand. I may have to run the return system similar to what you're doing and adapt to the 2x4 setup. That's a great idea. Thanks!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
About us
Holley has been the undisputed leader in fuel systems for over 100 years. Holley carburetors have powered every NASCAR® Sprint® Cup team and nearly every NHRA® Pro–Stock champion for four decades. Now, Holley EFI is dominating the performance world as well as our products for GM's LS engine. Holley's products also include performance fuel pumps, intake manifolds & engine dress–up products for street performance, race and marine applications. As a single solution, or partnered with products from other Holley companies - Hooker Headers, Flowtech Headers, NOS Nitrous, Weiand, Earl's Performance Plumbing, or Diablosport - Holley products can give you the edge you need over the competition.
Join us