My Jeep YJ Wrangler 2.5L (MPI not TBI) engine has no fuel pressure when it cold. Installed a new fuel pump and pressure regulator, swapped relays. When the Jeep is parked inside it runs and has fuel pressure. When we put the gauge on to check fuel pressure at the rail, inside we get around 39 psi. When we let the Jeep sit outside overnight and check pressure we have none. Any ideas? Thanks.