HARD OR NO START AFTER HOT SOAK. Cadillac Fleetwood 1984

HARD OR NO START

VEHICLES AFFECTED: 1981 DE VILLE, BROUGHAM, ELDORADO AND SEVILLE, 1981-1984 LIMO

Some 1981-1984 vehicles equipped with the V8-6-4 engine may experience either a hard or no start condition when the engine has reached normal operating temperatures and is turned off and allowed to sit for a 30 to 45 minute period in high ambient temperatures (hot soak). This condition may result from fuel vapourizing in the fuel meter assembly due to the transfer of heat from the engine to the throttle body assembly. A new thicker service throttle body gasket (P/N 1642864) is available through General Motors Service Parts Operation to address this condition.

Before replacing the throttle body gasket, the following procedure should be used to verify proper fuel system operation.

CAUTION:

WHEN TAKING THE FOLLOWING FUEL PRESSURE READINGS, BE SURE THE FUEL PRESSURE GAUGE IS SECURELY ATTACHED TO THE PRESSURE TEST POINT. BE CAREFUL TO ROUTE THE PRESSURE GAUGE HOSE AWAY FROM THE EXHAUST MANIFOLD, ANY OTHER HOT SURFACES, AND ANY SHARP EDGES THAT COULD CUT OR DAMAGE THE HOSE. FAILURE TO DO SO MAY RESULT IN A FUEL LEAK WHILE DIAGNOSING THE CAR.

1. Install a 0-100 kPa (0-15 PSI) fuel pressure gauge (from J-29658, J-35314 or equivalent) to the service fuel pressure tap. Note fuel pressure with the engine running. Fuel pressure should remain steady within the 60-80 kPa (9-12 PSI) range. If not, refer to DFI chart #4 "Fuel System Diagnosis" in the 1981 Service Information Manual.

2. Monitor and record the fuel pressure after the engine is turned off. Again record fuel pressure after a 30 minute hot soak. The final pressure should be within 15 kPa (2 PSI) of the starting fuel pressure. Should the fuel pressure drop more than 15 kPa (2 PSI), restrict the fuel feed and return lines and repeat test to evaluate fuel pressure drop. If the fuel pressure continues to drop more than 15 kPa (2 PSI) in 30 minutes, fuel is leaking internally within the fuel meter pressure regulator assembly. If the fuel pressure does not drop more than 15 kPa (2 PSI), fuel was leaking internally in the fuel pump or fuel pump coupler.

3. Check for a low fuel pump output pressure by disconnecting the fuel return line at the throttle body and install a plug in the throttle body opening. Note fuel pressure. Fuel pressure should increase to 100 kPa (15 PSI) or greater, if not replace the fuel pump.

4. Insulate the throttle body from the engine by installing the new service throttle body gasket P/N 1642864.

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.