Important: Before diagnosing this condition, check service bulletins for programmable read-only memory (PROM) updates.

DEFINITION: Involves a momentary lack of response as the accelerator is pushed down. This can occur at any vehicle speed. It is usually the most severe when first trying to make the vehicle move, as from a stop. Hesitation, sag, or stumble may cause the engine to stall if severe enough.

1

Were the Preliminary Checks performed?

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Go to Step 2

Go to Symptoms - Engine Controls

1. Measure the fuel system pressure. If the pressure is not within the 379-393 kPa (55-57 psi), service the fuel system as needed.
2. Inspect the throttle position (TP) sensor for binding or sticking. The TP sensor voltage should increase at a steady rate as the throttle is moved toward wide open throttle (WOT).

Is a repair necessary?

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Go to Step 3

Go to Step 4

Repair or replace any components as needed.

Did you complete the repair?

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System OK

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1. Inspect the manifold absolute pressure (MAP) sensor response and accuracy.
2. Inspect the fuel for water contamination.
3. Inspect the evaporative emission (EVAP) canister purge system for proper operation.

Is a repair necessary?

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Go to Step 5

Go to Step 6

Repair or replace any components as needed.

Did you complete the repair?

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System OK

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1. Disconnect all of the fuel injector harness connectors.
2. Connect an injector test light between the harness terminals of each fuel injector.
3. Note the test light while cranking the engine.

Does the test light blink on all connectors?

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Go to Step 8

Go to Step 7

1. Repair or replace the faulty fuel injector drive harness, the connector, or the connector terminal.
2. If the connections and the harnesses are good, replace the engine control module (ECM) for an internal open in the fuel injector driver circuit.

Did you complete the repair?

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System OK

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Measure the resistance of each fuel injector. The resistance will increase slightly at higher temperatures.

Is the fuel injector resistance within the specified range?

11.6-12.4 ohms

Go to Step 10

Go to Step 9

Replace any of the fuel injectors with a resistance that is out of specifications.

Did you complete the replacement?

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System OK

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Perform an injector balance test. Refer to Fuel Injector Balance Test with Special Tool .

Is a repair necessary?

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Go to Step 11

Go to Step 12

Replace any restricted or leaking fuel injectors.

Did you complete the repair?

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System OK

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Measure the fuel system pressure after a cold start or during moderate or full throttle acceleration.

Is the fuel pressure within the specified range?

379-393 kPa (55-57 psi)

Go to Step 14

Go to Step 13

Repair the restriction in the fuel system or replace the faulty fuel pump.

Did you complete the repair?

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System OK

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1. Inspect for faulty ignition wires.
2. Inspect for fouled spark plugs.
3. Inspect the ignition system output on each cylinder with a spark tester.

Is a repair necessary?

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Go to Step 15

Go to Step 16

Repair or replace any ignition components as needed.

Did you complete the repair?

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System OK

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1. Measure the generator output voltage.
2. Repair or replace the generator if the generator output is less than 12-16 volts.
3. Inspect the exhaust gas recirculation (EGR) valve operation.

Did you find and correct the condition?

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System OK

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