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Makes 🢒 GMC_Truck 🢒 2004 🢒 GMC W-Series Commercial (Crew) W4/W5 🢒 Bulletins 🢒 Info - Fuel Injection Pump Timing Procedure

Info - Fuel Injection Pump Timing Procedure

Subject:Fuel Injection Pump Timing Procedure

Models:1999-2004 Chevrolet W-Series Medium Duty Tilt Cab Models
1999-2004 GMC W-Series Medium Duty Tilt Cab Models
1999-2004 Isuzu NPR/NQR Commercial Medium Duty Models
With 4HE1-TC Engine


This bulletin is being issued to remind technicians of the correct timing procedure for the fuel injection pump on 4HE1-TC engines.

  1. Remove the number 1 cylinder glow plug. Rotate the engine until compressed air is felt out of the glow plug hole.
  2. REMOVE THE VALVE COVER AND MAKE SURE THAT THE CAMSHAFT TIMING MARK IS IN LINE WITH THE SURFACE OF THE HEAD. Refer to Section 6A6-52 of the 1999-2001 Service Manual-4HE1-TC Engine.

    3. Object Number: 1350391 Size: SH
    (1)13° Mark
    (2)9° Mark
    (3)7° Mark
    (4)Additional Mark (DO NOT USE THIS MARK)
    (5)Pulley Mark
  3. Align the crankshaft damper pulley timing mark (5) with the 13° mark (1). Note that the timing mark is located on the third landing/center landing of the damper pulley. Do not confuse this mark with the other mark (4). DO NOT USE THIS MARK (4) AS TIMING REFERENCE.
  4. Remove the timing inspection plug from the side of the cylinder block.
  5. Install the O-ring to the injection pump bracket.
  6. Align the injection pump bracket slit with the timer slit. Refer to Figure 18 on page 6C3-13 of the 1999-2001 Service Manual (4HE1-TC Engine for NPR/NPR HD/NQR/W3500/W4500/W5500 Models).
  7. Install the injection pump assembly to the cylinder block.

    8. Object Number: 1350392 Size: SH
    (1)8° Mark
    (2)13° Mark
    (3)Timing Inspection Hole
    (4)Pointer
  8. After mounting, make sure the 13° mark (2) is in position through the timing inspection hole (3).
  9. Lightly tighten the pump mounting nuts and bolts. Verify that there is no play between the cylinder block and the injection pump.
  10. Mount the injection pump bracket and retighten only the cylinder block side of the bolts.
  11. Turn the crankshaft in a clockwise direction until the timing mark on the crankshaft damper pulley is aligned with the 8° position. Verify that the injection pump 8° timing mark (1) lines up with the pointer (4) in the timing inspection hole.
  12. Tighten the bolts and nuts to the specified tightening specification. Refer to Section 6C3 of the 1999-2001 Service Manual (4HE1-TC Engine for NPR/NPR HD/NQR/W3500/W4500/W5500 Models).
  13. Rotate the engine two revolutions in a clockwise direction to 8° BTDC (without passing the 8° BTDC mark) on the crankshaft pulley. Verify again that the injection pump 8° timing mark (1) is aligned at the pointer mark (4) in the timing inspection hole.

Important: Refer to the Section 6C3, Fuel Injection System, of the 1999-2001 Service Manual (4HE1-TC Engine for NPR/NPR HD/NQR/W3500/W4500/W5500 Models) for any additional information.