VISUAL INSPECTION
Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. Inspect air induction system for possible vacuum leaks.
MECHANICAL INSPECTION
Note. Perform the following procedures in order. Skipping steps or procedures may lead to misdiagnosis.
Crankcase Pressure Test
This test is performed to measure crankcase pressure. Crankcase pressure is an indication of how well cylinders are sealing. Perform TEST 11: CRANKCASE PRESSURE TEST under ENGINE PERFORMANCE DIAGNOSTIC PROCEDURES in SYSTEM & COMPONENT TESTING - EEC-V - DIESEL article.
Compression Check (With Scan Tool)
Perform KOER CYLINDER CONTRIBUTION SELF-TEST under QUICK TEST in SELF-DIAGNOSTICS - EEC V - DIESEL article. Service any DTCs that are present. The following are possible causes for failing this test
- Broken Compression Rings
- Burnt Or Bent Valves
- Bent Push Rods
- Bent Connecting Rods
- Damaged Rocker Arms
- Faulty Fuel Injector Assembly
Compression Check (Without Scan Tool)
Check engine compression. If compression is less than 350 psi (2413 kPa) and differs from adjacent cylinder by more than 50 psi (345 kPa), repair engine mechanical condition.
Electric Fuel Pump Pressure Test
- Remove fuel line from outlet side of fuel pump. Install fuel pressure adapter between fuel outlet line and fuel pump. Connect fuel pressure adapter to 0-160 psi (0-1103 kPa) gauge at engine pressure tester. Run engine at idle and check for leaks from line to gauge. Measure fuel pressure with full load on engine. If fuel pressure measures less than 45-80 psi (310-552 kPa), check fuel regulator valve for debris.
- If fuel regulator is clear, replace electric fuel pump. After replacing fuel pump, recheck fuel pressure to verify that a restriction downstream of pump is not causing high fuel pressure which will cause pump to fail again.
Fuel Pressure Test
- On Econoline, remove doghouse cover and remove 1/8" pipe plug from top of left head. On Excursion and Pickup, remove 1/8" pipe plug from top front of right head. On all models, install Gauge Bar (014-0061). Run engine at idle and check for leaks from line and gauge. Measure pressure with full load on engine. If pressure is not 45-80 psi (310-552 kPa), replace fuel filter. Recheck fuel pressure, if fuel pressure is still less than specification, replace left head check valve on Econoline or right head check valve on Excursion and Pickup. Check valve is located between fuel inlet line and cylinder head.
- On Econoline, remove alternator and bracket if necessary. Remove 1/8" pipe plug from top front of right head. On Excursion and Pickup, remove 1/8" pipe plug from top rear of left head. On all models, install Gauge Bar (014-0061). Run engine at idle and check for leaks from line and gauge. Measure fuel pressure with full load on engine. If fuel pressure is not 45-80 psi (310-552 kPa), replace right head check valve on Econoline or left head check valve on Excursion and Pickup. Check valve is located between fuel inlet line and cylinder head.
NO-START DIAGNOSIS
Note. No-start is defined as engine cranks okay, but does not start. Engine may fire a few times.