Step 11 - After the gauge hose has been removed, install the fitting dust cap.
Step 12 - Using a clean shop towel wipe the area
free of fuel. Once testing is complete, inspect the area for fuel leaks.
Helpful Information Some vehicles are not designed with a fuel pressure test port, in which case
a fuel filter adapter must be used for the gauge connection. A fuel pressure regulator is controlled by a diaphragm and spring combination
in conjunction with intake manifold vacuum. When a fuel pressure regulator diaphragm
ruptures, it allows raw fuel to enter the vacuum feed line and into the engine.
This condition creates a rich
black smoke from
the tail pipe on start up and while running. Remove the vacuum line from the regulator,
if fuel is present, the regulator has failed. Some GM (CPI Injection) are designed with an internal regulator in which the
intake manifold must be removed to access.. Best Practices