How To Test GM Fuel Pressure Regulator

Application

GM’s 2.2 liter four cylinder engine entered service in 1990, initially with throttle body injection. In 1992 this went to multi-point fuel injection (MPFI) and in ’94 to sequential fuel injection (SFI.) The engine was used in a range of cars and light trucks including the Chevrolet Cavalier/Pontiac Sunfire, the Beretta, Corsica and S-10. In 2003 it was replaced by the 2.2 liter Ecotech.

These instructions relate specifically to the SFI engine, although the general principles will apply to other variants.

Tools required

A set of metric sockets and a flat bladed screwdriver are recommended. A T30 Torx driver is needed to remove the regulator from the fuel rail.

Removal procedure

1. Relieve the pressure in the fuel rail by pulling the fuel pump relay then attempting to start the engine.
2. Disconnect the air intake temperature sensor in the inlet duct running from filter box to ‘resonator,’ (the plastic molding sitting above the valve cover.)
3. Remove the intake duct.
4. Remove the resonator:
   1. Beneath the resonator a hose clip secures it to the throttle body. Loosen the screw.
   2. Undo the securing bolt at the front left (as you look at the engine.)
   3. Pull off the PCV hose.
   4. Lift off the resonator. The rubber collar that goes around the throttle body may pull off with it.
5. Under the resonator a black metal plate covers the fuel rail. Remove this by undoing the two nuts over studs securing it to the valve cover AND the three fasteners at the rear. Lift off the plate.
6. The fuel rail is now exposed and the regulator can be seen at the right end. Place a rag under the regulator to catch any dripping gas, then undo the large nut securing the fuel line to the regulator.
7. Pull off the vacuum hose at the left end of the regulator.
8. Undo the bolts holding the fuel rail in place and lift it out, carefully pulling the injectors from their ports.
9. Turning the rail reveals the Torx screw holding the regulator in place. Undo this and pull the regulator free.

Regulator replacement

1. Lubricate the ‘O’ ring in the rail with gasoline then fit the replacement regulator.
2. Replace the fuel rail, carefully guiding the injectors back into their ports. Lubricate with gas. Insert and tighten the fuel rail bolts.
3. Reattach the vacuum hose and fuel line. Tighten the retaining nut.
4. Refit the black cover plate.
5. Take the collar from around the throttle body and fit this to the base of the resonator. (This is easier than trying to guide the resonator into it.) Then replace the resonator on the engine, ensuring the integrity of the throttle body connection. Tighten the screw clamp.
6. Replace the inlet duct and reconnect the air temperature sensor.
7. Replace the fuel pump relay.

On first turning the key the fuel pump needs a few seconds to pressurize the rail. After this the engine should start and run smoothly.