Bleed pressure at service test port. This method will require collection of fuel as pressure is relieved. Use of a suitable container is required.

Locate service test port on fuel rail and remove protective cap.
CAUTION: DO NOT ALLOW SMOKING OR THE USE OF OPEN FLAMES IN THE AREA WHERE WORK ON THE FUEL OR EVAP SYSTEM IS TAKING PLACE. ANYTIME WORK IS BEING DONE ON THE FUEL SYSTEM, DISCONNECT THE NEGATIVE BATTERY CABLE, EXCEPT FOR THOSE TESTS WHERE BATTERY VOLTAGE IS REQUIRED.
Connect Gauge Bar (53476) to Fuel Gauge Pressure Adapter (309725) using a flexible hose from Gauge Bar Set (SA9127E).
Make sure needle valve on pressure adapter is closed (Off).
NOTE: Do not use any tools to tighten the adapter to the fuel line pressure port. If the adapter will not seal with finger tightening, then the seal is defective or damaged and needs to be replaced. Excessive torque on the adapter will damage the fuel line test port.
Connect pressure adapter to fuel line test port.

Fig 1: Connecting Fuel System Pressure Tester
Courtesy of GENERAL MOTORS CORP.
Route drain hose from pressure adapter into a suitable container or route fuel back to fuel tank.
Open valve on pressure adapter and bleed off pressure (and fuel).

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

Method 2