Hard Start
Checks
| Action
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DEFINITION: The engine cranks OK, but does not start for a long time. The engine
does eventually run, or may start but immediately dies.
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Preliminary Checks
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| • | Make sure the driver is using the correct starting procedure. |
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Sensor Checks
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| • | Check the engine coolant temperature (ECT) sensor using a scan tool and
compare the coolant temperature with the ambient air temperature on a cold engine.
If the coolant temperature reading is 5°C (41°F) more or less than the ambient
air temperature, check for high resistance in the coolant sensor circuit or a shifted
sensor. Refer to
Temperature Versus Resistance. |
| • | Check the throttle position (TP) sensor. A sticking throttle shaft or
a binding throttle linkage will causes a high TP sensor voltage (open throttle indication).
Under these conditions the PCM may not control the idle. Monitor the TP sensor angle
with the scan tool. The indicated angle should be aproximately 11% with throttle
closed. |
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Fuel System Checks
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| • | Check for no Crank Signal to the PCM (C1-11) if the vehicle is slower
to start in cold weather. Observe the Starter Switch parameter on a scan tool while
cranking the engine. The PCM provides slightly more fuel for engine start up when
receiving the Crank input. |
| • | Check the fuel pump check valve. A faulty in-tank fuel pump check valve
will allow the fuel in the lines to drain back to the tank after stopping the engine.
This condition is especially troublesome on hot soak restarts. In order to check for
this condition perform the following steps: |
| 1. | Turn OFF the ignition. |
| 2. | Disconnect the fuel line at the fuel filter. |
| 3. | Remove the fuel tank filler cap. |
| 4. | Connect a radiator test pump to the fuel line and apply 102 kPa
(15 psi) of pressure. The check valve is OK if the pressure holds for 60 seconds. |
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Ignition System Checks
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| • | Check for the proper secondary voltage output with a spark tester (J 26792
or equivalent). |
| • | Check the spark plugs for any of the following conditions: |
| - | Wet (fuel fouled) plugs. |
| - | A terminal screw that is bent or loose (rotate and pull). |
| - | A ceramic insulator that has cracks, carbon tracking or deposits (red
or black dust) |
| - | A tip insulator that has cracks, carbon tracking, deposits (oil, carbon,
glazing, fuel additive), or is loose (rattles). |
| - | A center electrode that is loose (wiggles side to side) |
| - | An incorrect spark plug gap that is too large or too small. |
| - | Platinum pads that are missing. |
| • | Check for bare or shorted ignition wires. |
| • | Check for loose ignition coil connections. |
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Additional Checks
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| • | Check the IAC system for proper operation. An IAC valve that is positioned
incorrectly, can hinder normal engine start up. |
| • | Check the Service Bulletins for any updates. |
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