Possible Causes

• Broken compression rings.
• Leaking or bent valves.
• Bent push rods.
• Bent connecting rods.
• Damaged rocker arms.
• Faulty fuel injector assembly.

See 7.3L V8 TURBO DIESEL article in ENGINES for engine mechanical diagnostic procedures. If base engine condition meets specifications, injector may not be functioning correctly and will need replacement. Fuel injector solenoid and wiring should have been checked in previous tests.