GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Monte Carlo 🢒 Engine 🢒 Engine Controls - 3.1L 🢒 Hard Start

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DEFINITION: Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately dies.

Preliminary
    •  Refer to Intermittent Conditions Before Starting.
    •  Search for bulletins.

Sensor/System
    • Check Engine Coolant Temperature (ECT) sensor for being shifted in value. Connect a Scan Tool and compare Engine Coolant Temperature with Intake Air Temperature on a cold engine. The ECT and IAT should be within ± 3°C (5°F) of each other. Check the resistance of the ECT sensor if the temperature is out of range with the IAT sensor. Refer to the Temperature vs Resistance Table. If the ECT sensor resistance is not within the specification, refer to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage or DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage .
    •  Check for 24X Crankshaft Position and Camshaft Position Sensors on scan tool. If both are not responding, check the sensor feed circuit (Both sensors use a common feed circuit).
    •  Check Mass Air Flow sensor for proper installation and conditions. A MAF sensor with a damaged honeycomb may cause a hard start. Refer to Information Sensors/Switches Description .
    •  Using a scan tool, check IAC operation. Refer to Idle Air Control (IAC) System Diagnosis .
    •  Check the EGR system for proper sealing/connections and operation. Refer to Exhaust Gas Recirculation (EGR) System Description .

Fuel System
    • Check the fuel pump relay circuit for proper operation. Refer to Fuel Pump Electrical Circuit Diagnosis .
    • Check for low fuel pressure. Refer to Fuel System Pressure Test .
    •  Check for fuel contamination. Refer to Fuel Tank Leak Check .

Ignition System
    • Check for proper ignition voltage output using the following steps:
       -  Clip the J 26792 spark tester to engine ground.
       -  Connect one end of a spark plug wire to the J 26792 spark tester; leave the other end of the spark plug wire to the coil being tested.
       -  Connect one end of another spark plug wire to the other coil tower; connect the other end of the spark plug wire to ground.
       -  Crank the engine while observing the J 26792 spark tester; a spark should be observed.
       -  Repeat the above steps for each coil.
    •  If adequate spark is not present at the coil(s), check for the following conditions:
       -  Coil(s)--Cracks, carbon tracking/arcing, or a resistance value outside the specified range.

Coil Resistance
5000-8000 ohms (5K-8K ohms)

       -  Spark Plug wires--Signs of arcing/cross firing, cracks, carbon tracking, plug boot damage, pinched, improper routing, or a resistance value outside the specified range.

Spark Plug Wire Resistance
600ohms per foot (1 968ohms per meter).

    Important: :  Spraying the secondary ignition wires with a light mist of water may help locate an intermittent problem. Ignition components will arc to ground when a secondary component is faulty.

       -  Defective module.
       -  Ignition System Wiring--Loose ignition module feed or ground connection, or damaged system wiring.
    •  Remove spark plugs and check for the following:
       -  Fouled plugs
       -  Cracks
       -  Wear
       -  Improper gap
       -  Burned or damaged electrodes
       -  Improper heat range or reach
    •  If spark plugs are gas or oil fouled, the cause of the fouling must be determined before replacing the spark plugs.

Engine Mechanical
    • Excessive oil in combustion chamber--Leaking valve seals. Refer to Base Engine Misfire Diagnosis .
    •  Low cylinder compression. Refer to Engine Compression Test
    •  For incorrect basic engine parts. Inspect the following:
       -  Cylinder heads
       -  Camshaft and valve train components
       -  Pistons, etc.
       -  Refer to Base Engine Misfire Diagnosis .