Fuel Rail


Removing the Fuel Rail

  • The procedure for removing and replacing the fuel rail, injectors, and pressure regulator varies depending on the vehicle.
  • On some applications, certain components must be removed to gain access to these components.
  • The system must be relieved of any and all pressure before the fuel lines are opened to remove any of the components.
    • Connect a 12-volt power supply to the cigarette lighter and disconnect the battery negative cable. If the vehicle is equipped with an airbag, wait one minute.
  • Before removing the fuel rail, wipe off any dirt from the fuel rail with a shop towel.
  • Then loosen the fuel line clamps on the fuel rail, if so equipped.
  • If these lines have quick-disconnect fitting, grasp the larger collar on the connector and twist in either direction while pulling on the line to remove the fuel supply and return lines.
Fuel supply and return lines connected to the fuel rail. Courtesy of General Motors Corporation - Oldsmobile Division.
  • Now, remove the vacuum line from the pressure regulator and disconnect the electrical connectors from the injectors.
Quick disconnect fuel line fittings. Courtesy of Oldsmobile Motor Division - GMC.
  • The fuel rail is now ready to be removed.
  • On some engines, the fuel rail is held in place by bolts; they need to be removed before pulling the fuel rail free.
  • When pulling the fuel rail away from the engine, pull with equal force on each side of the fuel rail to remove the rail and injectors.
  • Prior to removing the injectors and the pressure regulator, the fuel rail should be cleaned with a spray type engine cleaner. Normally the approved cleaners are listed in the service manual.
Do not use compressed air to flush or clean the fuel rail. Compressed air contains water, which may contaminate the fuel rail.
Do not immerse the fuel rail, injectors, or pressure regulator in any type of cleaning solvent. This action may damage and contaminate these components.
  • Clean all components with a clean shop towel as they are removed.
Cap injector openings in the intake manifold to prevent the entry of dirt and other particles. Also, after the injectors and pressure regulator are removed from the fuel rail, cap all fuel rail openings to keep dirt out of the fuel rail.
  • Be careful not to damage fuel rail openings and injector tips.
  • Check all injector and pressure regulator openings in the fuel rail for metal burrs and damage.

Installing the Fuel Rail

  • If the same injectors and pressure regulators are reinstalled, replace all O-rings and lightly coat each O-ring with engine oil.
  • Install the pressure regulator in the fuel rail and position the vacuum fitting on the regulator in the original direction.
  • Install the snap ring above the pressure regulator.
  • Install the injectors in the fuel rail.
  • Install the fuel rail while guiding each injector into the proper intake manifold opening. Be sure the injector terminals are positioned so they are accessible to the electrical connectors.
  • Tighten the fuel rail hold down bolts alternately and torque them to specifications.
  • Reconnect the vacuum hose on the pressure regulator.
  • Install the fuel supply and fuel return lines on the fuel rail.
  • Install the injector electrical connectors.
  • Connect the negative battery terminal, and disconnect the 12V power supply from the cigarette lighter.
  • Start the engine and check for fuel leaks at the rail and be sure the engine operation is normal.

Relieving Pressure from Fuel System

A very simple procedure for bleeding pressure from the fuel system is as follows:

  • Disconnect the fuel pump electrical connector or remove the fuel pump relay or fuse.
  • Crank the engine briefly to drop the fuel pressure or run the engine until it stalls.

There are other methods used to bleed pressure from the fuel system.

  • One other way is to energize the fuel injector by applying positive voltage to one of the injector terminals and a ground to the other.
12 volts should not be applied to an injector for longer than 5 seconds.

Another pressure bleeding procedure is to:

  • Disconnect the battery ground cable.
  • Remove the filler cap from the fuel tank.
  • Some systems have a Schrader valve that can be used to bleed off pressure from the system before disassembly (A Schrader valve is the kind that is found on tire valve stems).
  • Remove the threaded cap from the fuel pressure test port on the fuel rail to find the Schrader valve.
  • Use a special hose that has a pressure relieving tool on the fuel rail end to drain fuel to a gas can.