Checks
| Action
|
DEFINITION: The
vehicle has a momentary lack of response when depressing the accelerator pedal.
The condition can occur at any vehicle speed. The condition is usually
most severe when attempting to make the vehicle move, as from a stop
sign. An extremely severe condition may cause the engine to stall.
|
Preliminary
Checks
| Refer
to Important Preliminary Checks in
Symptoms - Engine Controls
.
|
Fuel System Checks
|
| | Inspect for low pressure during
moderate or full throttle acceleration. If the fuel pressure drops below
specification, there is possibly a low or high pressure regulator
fault or a fuel system restriction. |
| • | Test for proper EVAP purge system operation. |
| • | Inspect for proper installation of the gas distribution adaptor
(GDA). |
| • | Inspect for air leaks at the GDA. |
|
Sensor Checks
|
| • | Test for proper TP sensor operation. A TP sensor that does not
respond quickly and accurately to throttle plate movement may cause this
symptom. |
| • | Test for proper MAP sensor operation. A MAP sensor that does not
respond quickly and accurately to manifold pressure changes may cause
this symptom. |
|
Ignition System Checks
|
| | Important:: A higher secondary ignition voltage is required to operate the vehicle
on CNG than on gasoline. A vehicle that operates normally on gasoline
does not indicate a fully functional ignition system.
|
| • | Check for proper secondary ignition system voltage output using ONLY
the J 26792
Spark Tester. |
| • | Inspect for fouled spark plugs. |
| | If fouled spark plugs
are indicated the reason for the fouling must be found and corrected. |
| • | Test for faulty spark plug wires. |
| • | Test for an open ignition system ground (if equipped). |
|
Additional Checks
|
| • | Review service bulletins for control module (AF ECM, VCM / PCM
or ECM ) programming updates -- re-flashing. |
| • | Inspect for manifold or air induction system leaks. |
| • | Test for proper generator operation. |
|
