Compression
Check engine mechanical condition using a compression gauge, vacuum gauge or engine analyzer. If using engine analyzer, see engine analyzer manual for specific instructions. Compression pressures are considered within specifications if lowest reading cylinder is within 75 percent of highest reading cylinder.
| WARNING | Because fuel injectors on many models are triggered by the ignition switch, DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine to prevent fire hazard or engine oiling system contamination. |
Exhaust System Backpressure
Using a vacuum or pressure gauge, check exhaust system. Remove Heated Oxygen Sensor (HO2S) or air injection check valve (if equipped). Connect a 0-5 psi pressure gauge, and run engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.
If using a vacuum gauge, connect vacuum gauge hose to intake manifold vacuum port, and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, check exhaust system for restrictions.
PRELIMINARY CHECKS
Ensure following systems and components are in good condition and operating properly before diagnosing problems in fuel injection system.
- Check battery and charging system condition.
- Check all wiring and vacuum connections.
- Check air cleaner and ducting.
- Check state of tune.
- Check fuel delivery system.
- Check cooling system.
- Check inertia fuel shutoff switch.
- Check for hydrostatic lock (liquid in cylinder).
- Check fuel tank contents and fuel gauge accuracy.
- Check for dirt, water or other contamination in fuel.
- Check fuel lines and fittings for leaks.
- Check fuel delivery system for proper pressure and volume.
- Check for inoperative fuel injectors.
- Check for improperly installed electronic equipment such as anti-theft system, CB radio, cellular telephone or stereo.
Engine Does Not Crank
Check for enabled anti-theft system. Check starting and charging system for correct operation. Check for hydrostatic lock (liquid in cylinder). Repair as necessary.
Engine Cranks But Will Not Start
- Check fuel tank contents and fuel gauge accuracy. Check for dirt, water or contamination in fuel.
- Check fuel lines and fittings for leaks. If no leaks are found, check fuel delivery system for proper pressure and volumes. Reset Inertia Fuel Shutoff (IFS) switch (if necessary).
- Check for damaged or contaminated fuel injector wiring harness and connector. Ensure fuel injectors pulse when engine is cranked.
- Check ignition system for strong secondary current at spark plugs. If no spark exists or if spark is weak, go to step 1) of CIRCUIT TEST JD in the «TESTS W/CODES - 5.4L»(ref-23995) article.
FUEL SYSTEM PRESSURE RELEASE
| WARNING | Always relieve fuel pressure before disconnecting any component under fuel pressure. DO NOT allow fuel to contact engine or electrical components. |
- Remove fuel tank cap. Using Fuel Pressure Gauge (T80L-9974-B), release pressure from system at pressure relief valve (Schrader valve), located on fuel injection manifold rail. Place fuel pressure gauge in a suitable container. Using gauge, release pressure from system.
- If fuel pressure gauge is not available, disconnect Inertia Fuel Shutoff (IFS) switch. See INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION table. Remove fuel cap to release fuel tank pressure. Crank engine for 15 seconds to release system pressure.
| Application | Location |
|---|---|
| Van | Behind Right Kick Panel |
INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION
FUEL PRESSURE
| WARNING | Inspect fuel system for leaks or damage before testing fuel pump. |
- Release fuel pressure. Install fuel pressure gauge. Turn ignition on and read fuel pressure. Start engine and read fuel pressure. For fuel pressure specifications, see «FUEL PRESSURE SPECIFICATIONS»(ref-123323) article.
- If fuel pressure is not within specifications, check fuel pressure regulator. With engine running, connect hand vacuum pump and apply vacuum to regulator.
- Ensure fuel pressure changes as vacuum at regulator is increased and decreased. If no pressure change occurs, replace regulator and recheck system. For additional testing information, go to CIRCUIT TEST HC in «TESTS W/CODES - 5.4L»(ref-23995) article.
| Application | Specification |
|---|---|
| Fuel Line Pressure | (1) |
| Fuel Volume | (2) |
| (1) For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. (2) Volume is one pt. (.5L) in 30 seconds. | |
| (1) | For fuel pressure specifications, see FUEL PRESSURE SPECIFICATIONS article. |
| (2) | Volume is one pt. (.5L) in 30 seconds. |
FUEL PRESSURE SPECIFICATIONS
Fuel Injector Resistance
Disconnect injector harness connectors. Using digital ohmmeter, measure resistance between injector terminals. See INDIVIDUAL INJECTOR RESISTANCE table. Replace any injector not within specification.
Fuel Injector Check
Start engine and allow to idle. If engine will not start, crank engine for 10 seconds. Using a stethoscope, listen for clicking sound at each injector. If clicking sound is heard, fuel injector is operating. If clicking sound is not heard, go to step 8) of CIRCUIT TEST HD in the TESTS W/CODES - 5.4L article.
Note. For additional testing and information, see FUEL SYSTEM in SYSTEM/COMPONENT TESTS - 5.4L article.
| Engine | Ohms |
|---|---|
| 5.4L | 11-18 |
| (1) Resistance values are for a single injector. | |
| (1) | Resistance values are for a single injector. |
INDIVIDUAL INJECTOR RESISTANCE (1)
INERTIA FUEL SHUTOFF (IFS) SWITCH
| WARNING | DO NOT reset IFS switch until fuel system has been inspected for leaks. |
- In event of a collision, electrical contacts in inertia switch open, automatically shutting off fuel pump. Fuel pump shuts off even if engine does not stop running. Engine will stops due to lack of fuel.
- Engine cannot be restarted until inertia switch is manually reset. To reset inertia switch, depress button on switch. See INERTIA FUEL SHUTOFF (IFS) SWITCH LOCATION table under «FUEL SYSTEM PRESSURE RELEASE»(ref-23994-S17479693472001010400000) .
Definition
No-start is defined as engine cranks okay, but does not start. Engine may fire a few times.
Before diagnosing problems in ignition system, ensure following systems and components are in good condition and operating properly.
- Battery.
- Timing belt or chain.
- Fuel delivery and injection system.
- All wiring and vacuum connections.
- Air cleaner and ducts.
- Cooling system.
Spark Check
- Perform self diagnostic QUICK TEST to check for ignition-related fault codes, and repair as necessary. See QUICK TEST in «TESTS W/CODES - 5.4L»(ref-23995) article. If no fault codes are retrieved, check ignition system wiring harness connectors for corrosion and tight fit. See the «WIRING DIAGRAMS - 5.4L»(ref-23997) article. Clean or repair connectors as necessary.
- If wiring and connectors are okay, use Neon Bulb Spark Tester (D8IP-6666-A) to check for spark at each spark plug wire while cranking engine. If spark is strong and consistent at each spark plug (one spark per crankshaft revolution), ignition system is okay. If spark is not present, go to CIRCUIT TEST JD in «TESTS W/CODES - 5.4L»(ref-23995) article.
IGNITION COIL RESISTANCE
| Application | Primary | Secondary |
|---|---|---|
| Distributorless Ignition | .5 | (1) |
| (1) Resistance values not available at time of publication. | ||
| (1) | Resistance values not available at time of publication. |
IGNITION COIL RESISTANCE
IDLE SPEED & IGNITION TIMING
Ensure idle speed and ignition timing are set to specification. See appropriate table. For adjustment procedures, see the ADJUSTMENTS - 5.4L article.
Note. Always refer to Emission Control Label in engine compartment before attempting service. If manual and label differ, always use emission label specifications.
| Application | RPM |
|---|---|
| 5.4L | (1) |
| (1) Idle speed is computer controlled and is not adjustable. | |
| (1) | Idle speed is computer controlled and is not adjustable. |
IDLE RPM SPECIFICATION
| Application | Degrees BTDC |
|---|---|
| 5.4L | (1) 8-10 |
| (1) With SPOUT in-line connector unplugged. | |
| (1) | With SPOUT in-line connector unplugged. |
BASE IGNITION TIMING
SUMMARY
If no faults were found while performing BASIC DIAGNOSTIC PROCEDURES, proceed to TESTS W/CODES - 5.4L article. If no trouble codes are found self-diagnostics, proceed to TESTS W/O CODES - 5.4L article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.