Fuel Injection Pump Timing Adjustment Procedure (EFI/MFI)
WARNING: This page is about a different car, the 2003 GMC Sierra, 2003 GMC Cab & Chassis Sierra, 2003 Chevrolet Silverado, and 2003 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
- Connect scan tool. Operate engine until coolant temperature is greater than 170°F (77°C). Leave engine running. Using scan tool, activate TIME SET (if time set has been activated correctly, DES. INJ. TIME on scan tool will read 0.0 degrees).
- If engine does not stall, go to next step. If engine stalls, loosen pump nuts. Slightly rotate pump toward driver-side of vehicle. Tighten nuts. Repeat step 1.
- Observe ACT. INJ. TIME value (this is the current timing). If timing is not 3.5 degrees BTDC, shut engine off. Loosen pump nuts. Rotate pump as necessary (one mm = 2 degrees). Tighten pump nuts. Start engine. Observe ACT. INJ. TIME value. If necessary, repeat adjustment procedure until average fluctuation of ACT. INJ. TIME is 3.5 degrees.
NOTE:
ACT. INJ. TIME value on scan tool will fluctuate. Average reading should be 3.5 degrees.