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Home >> GMC >> 1995 >> Forward Control 7.4 N >> Repair and Diagnosis >> External Pages >> Different car >> Section 91 (Engine Controls - System/Component Tests - 5.9L Diesel) >> Fuel System >> Fuel Control >> Fuel Injector
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Fuel Injector

WARNING: This page is about a different car, the 1995 Dodge Pickup and 1995 Dodge Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
  1. A defective fuel injector may cause a fuel knock, poor engine performance, Black smoke, rough engine idle, and poor fuel economy. Since a leaking high-pressure fuel line can cause the same symptoms, check for a leaking line before checking for a defective fuel injector.
  2. To check for defective fuel injector, start engine. With engine idling, loosen high-pressure fuel line nut at fuel injector. Use care when working around high-pressure fuel lines, as fuel is under extreme pressure and could penetrate skin, causing personal injury.
  3. Listen for a change in engine idle speed and then tighten high-pressure fuel line nut to 22 ft. lbs. (30 N.m). If fuel injector is operating properly, engine idle speed should decrease when high-pressure fuel line nut is loosened.
  4. Repeat procedure on each fuel injector. If an injector is suspected to be faulty, remove injector, and test it with a diesel fuel injector tester. Replace injector if it does not open when pressure is at about 3822 psi (26,252 kPa).
  5. Ensure all high-pressure fuel line nuts are tightened to 22 ft. lbs. (30 N.m). Bleed fuel system. See REMOVE/INSTALL/OVERHAUL - 5.9L DIESEL article in the ENGINE PERFORMANCE section.