Diagnose This! Pressure Problem – July 2008

Each month in Diagnose This! we present a real-life service scenario with clues as to what the ultimate diagnosis was. If you think you know the answer, be the first to e-mail Dsmith@rrpub.com with the correct response for free Truck Parts & Service merchandise. The answer will be revealed in a future issue of the magazine.

This month’s Diagnose This! is submitted by ASE master technician and owner of Fleet Guardian, Damon Russell.

Vehicle: 2002 Peterbilt Model 330

Key component: Caterpillar 3126 engine

Scenario: Vehicle developed sudden stalling problem accompanied by “Check Engine” light illuminating. A scan of the electronic control module (ECM) showed fault code 164-11 – injection actuation pressure fault – occurring 76 times during the past two engine hours. Technicians changed the engine oil and the vehicle was retested. The same fault remained.

Clues: Graphing scan data showed proper pressure on acceleration, exactly matching desired pressure. The fault could not be duplicated with no-load throttle snaps, as shown in Photo 1.

A new injection pressure regulator (IPR) was installed and the injection pressure sensor was compared with specs and was verified OK.

Injection pressure testing with CAT ET would duplicate the fault every time, see Photo 2.

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