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Deceleration Fuel Shutoff

To reduce exhaust emissions and fuel consumption, the control unit shuts off the fuel supply whenever the throttle is closed and engine rpm is significantly above idle.

This control function can be checked by measuring differential pressure regulator current under deceleration conditions. For this test the engine should be warm-engine oil temperature at least 140°F (60°C).

To test:
1. Connect an ohmmeter to measure differential pressure regulator current, as described in 6.1 Air Flow Measurement and Fuel Metering.
2. Disconnect the harness connector from the coolant temperature sensor.
3. Switch the ignition on. Differential pressure regulator current should be between 90 and 110 mA.


If differential pressure regulator current reads negative, reverse the test leads.

4. Start the engine.
5. Open the throttle to raise the engine speed to at least 3000 rpm, then let it close suddenly. Differential pressure regulator current should briefly read in the negative range.

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