Dodge ZB 2005 Service Manual page 1214

P0300-MULTIPLE CYLINDER MIS-FIRE —
TEST
5 Turn the ignition off.
Remove the Spark Plug.
Inspect the Spark Plug for the following conditions.
- Cracks
- Carbon Tracking
- Foreign Material
- Gap size out of specifications
- Loose or broke electrode
NOTE: Lightly tap the bottom of the spark plug on a solid surface. The
electrode in the spark plug should not move.
Were any of the above condition present?
Yes → Replace the Spark Plug.
→ Go To 6
No
6 Warning: The fuel system is under a constant pressure (even with the engine
off). Before testing or servicing any fuel system hose, fitting or line, the fuel
system pressure must be released.
Install a fuel pressure gauge to the fuel rail.
Start the engine and observe the fuel pressure reading.
NOTE: Fuel pressure specification is 379 KPa +/- 14 KPa (55 psi +/- 2 psi).
Choose a conclusion that best matches your fuel pressure reading.
Within Specification
Below Specification
Above Specification
7 NOTE: Before continuing visually and physically inspect the fuel delivery
system for external leaks or damage. Repair /replace as necessary.
Turn the ignition off.
WARNING: The fuel system is under a constant pressure even with the
engine off. Before testing or servicing any fuel system hose, fitting or line,
the fuel system pressure must be released.
Install special tool #6539 (5/16 ) or #6631 (3/8 ) fuel line adapter.
Install the fuel pressure gauge.
Start the engine and allow the fuel system to reach maximum pressure.
Turn the ignition off.
NOTE: Fuel specification is 379 KPa +/- 14 KPa (55 psi +/- 2 psi).
Using special tool #C4390, Hose Clamp Pliers, pinch the rubber fuel line between the
fuel pressure gauge and the engine.
Monitor the fuel pressure gauge for a minimum of 5 minutes.
NOTE: The pressure should not fall below 241 KPa (35 psi)
Does the gauge fall below the listed specification?
Yes → Replace the leaking Fuel Injector(s).
→ Go To 8
No
ACTION
Perform POWERTRAIN VERIFICATION TEST VER - 5.
Go To 7
Go To 12
Replace the fuel filter/pressure regulator.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
Perform POWERTRAIN VERIFICATION TEST VER - 5.
DRIVEABILITY - GAS
Continued
93
APPLICABILITY
All
All
All