Compare fuel pressure gauge readings to specification. See Fig. 167. If fuel pressure gauge readings are
within specification, go to next step. If fuel pressure gauge readings are not within specification, check
and repair fuel system as necessary.
11) Check Ability Of Fuel System To Hold Fuel Pressure
Start engine and allow to idle. Record fuel pressure gauge reading. Increase engine speed to 2500 RPM
and maintain for one minute. Check for fuel leaking from around fuel injectors, fuel pressure regulator
and fuel lines. Repair as necessary. If fuel pressure gauge reading remains within 5 psi (34 kPa) of
specification for one minute, go to step 12). If fuel pressure gauge reading does not remain within 5 psi
(34 kPa) of specification for one minute, check fuel system for faults and repair as necessary.
12) Check Fuel Injector Flow & Leakage
Turn ignition switch to OFF position. Use Rotunda fuel injector tester from Kit (113-00114) to flow test
fuel injectors. Follow injector tester instructions. Fuel injector flow rate should be within specification. If
flow rate for each fuel injector is within specification, fuel delivery system is not the likely cause of
misfire DTC. Go to step 20). If flow rate for any fuel injector is not within specification, clean or replace
defective fuel injector(s).
20) Check Vacuum System
Inspect all vacuum hoses for kinks or damage. Ensure all vacuum connections are clean and tight. Repair
as necessary and perform DRIVE CYCLES. Ensure MISFIRE & FUEL MONITOR PROCEDURES are
performed to verify repair. If vacuum system is okay, go to next step.
21) Check Crankshaft Damper & Pulley Assembly
On models equipped with crankshaft pulley-mounted pulse ring, check crank pulley and pulse ring for
damage or looseness. On models not equipped with crankshaft pulley-mounted pulse ring, remove front
cover if necessary. Check crank pulley and pulse ring for damage or looseness. On all models, repair as
necessary and disconnect battery for 5 minutes to allow PCM to learn new data. If no faults are found, go
to next step.
22) Check Evaporative Emission System
Inspect carbon (EVAP) canister for fuel saturation. Replace carbon (EVAP) canister if liquid fuel is
present. Perform DRIVE CYCLES. Ensure MISFIRE & FUEL MONITOR PROCEDURES are
performed to verify repair. If carbon (EVAP) canister is okay, go to next step.
WARNING:
Always refer to safety procedures to reduce possibility of injury. See
FUEL SYSTEM SAFETY PRECAUTIONS.
NOTE:
A break in step numbering sequence occurs at this point. Procedure skips
from step 12) to step 20). No test procedures have been omitted.
NOTE:
The MISFIRE MONITOR can be affected by evaporative emission system.
2003 Ford Pickup F150
2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline