Fuel pressure low

Hello,

Common problems on the second generation CSFI system include leaky O-ring seals, leaky fuel pressure regulator, leaks in the fuel pulsator or damper inside the fuel tank (causes a loss of fuel pressure), and leaky or gummed-up spray nozzles.

Please take care when working with flammable liquids!

To diagnose which side of the fuel system, supply or regulated, is faulty we will need to check the fuel pressure at the outlet of the fuel filter first. so, disconnect the outlet pipe at the fuel filter and fit a suitable fuel pressure gauge to the filter. Universal fuel pressure gauge kits can be purchased online or from spares retailers. See 2nd image below.

How to use a fuel pressure tester.
https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

You should see a reading of around 70-100 PSI at the filter outlet, this is unregulated direct feed from the in-tank fuel pump. If this pressure is not reached, then there is a problem with the in-tank pump.

At the fuel rail pressure port, we should see a steady fuel pressure of 58-65 psi. A lower pressure would indicate a leak at either the poppet style injectors or fuel pressure regulator.
To access you will have to remove the top part of the intake plenum. See picture below, it shows the upper intake plenum removed, exposing the injector body and 6 injector feed lines.

To test the fuel pressure regulator, attach the fuel lines again and pressurize the system. Then remove the vacuum pipe at the fuel pressure regulator and check if any fuel leaks out of the pipe. At the same time, you can check if any of the poppet type injectors are leaking. Carefully remove each from the lower intake plenum and see if fuel is dripping from the nozzle tips.

When refitting the fuel supply lines to the injector main body take care to assemble the O-rings and washers in the correct order. See image 3 below.

Please let us know how you get along.

Cheers, Boris