HARD START OR EXTENDED CRANK AFTER HOT OR COLD SOAK

1985-86 6000, SUNBIRD, FIREBIRD AND FIERO VEHICLES EQUIPPED WITH 2.8L PFI ENGINES

Some 1985-86 6000, Sunbird, Firebird and Fiero vehicle with the 2.8L MPFI engine may experience a hard start condition after a hot soak (2 or more hours) or cold soak (overnight). This condition may be injector related, and should be diagnosed using procedures defined in the following steps.

NOTICE: THIS HARD START CONDITION SHOULD NOT BE CONFUSED WITH ROUGH IDLE OR POOR ACCELERATION DUE TO RESTRICTED FUEL INJECTORS. VEHICLES WITH ROUGH IDLE OR POOR ACCELERATION SHOULD BE SER- VICED USING PROCEDURES FOR ON-VEHICLE CLEANING OF INJECTORS DEFINED IN PREVIOUS SERVICE BULLETINS.

1. Attach a fuel pressure gage to the fuel rail pressure fitting. Turn ignition to "on" and pressurize fuel system.

2. If the fuel pressure leaks down more than 10 PSI in 2 minutes with the fuel feed and fuel return lines restricted, proceed to step 3. If the pressure does not leak down, perform procedures in Chart A-7, Fuel System Diagnosis, in Section 6E3 of the Service Manual.

3. Locate and replace leaking injectors using the following procedure.

- Connect fuel gage, J-34730-1 or equivalent to fuel pressure valve. Wrap a shop towel around fitting while connecting gage to avoid spillage. Route bleed hose into an approved container and open valve to bleed system.

- Remove plenum, cold start valve and remove fuel rail bolts. Leave fuel lines connected.

- Reconnect cold start valve. Connect one end of a hose to the nozzle of cold start valve and route the other end into a gasoline container.

- Lift fuel rails out just enough to leave injector nozzle in the ports.

CAUTION:

BE SURE INJECTOR(S) ARE NOT ALLOWED TO SPRAY ON ENGINE AND AND THAT INJECTOR RETAINING CLIPS ARE INTACT. THIS SHOULD BE CAREFULLY FOLLOWED TO PREVENT SPRAY ON ENGINE WHICH COULD CAUSE A FIRE HAZARD.

- Pressurize the fuel system.

- Lift each side of fuel rail up and observe for leaking injectors or cold start valve. Replace any parts that leak in excess of the following rates:

Component Part Maximum Leak Rate * -------------- ----------------- Injector 1 drop / min. Cold Start Valve 1 drop / min.

* Injectors and cold start valve should be wiped dry with a clean shop towel prior to timing the injector leak rate.

Use applicable labor times and operation numbers.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.