99 tahoe fuel pressure runs about 50psi i understand this is low pressure bleeds off fairly quickly. You turn it on comes up about 58psi then drops to 50psi. Idles about 50psi. Some throttle comes up a little but never over 60psi which i understand the spec is 60-66psi. Thought FPR, replaced no help. So i took the fuel lines out of injector spider and ran a test straight off the pump. Pressure came up to about 10psi when on and immediately dropped to 0psi. Fuel pump check valve? She is running fairly rough at at idle. Thanks for any advice.