Injection Pump Timing

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 GMC C3500 HD, and 2002 Chevrolet RV Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

Original factory injection pump timing is usually marked with a static timing mark (a line scribed across both the pump mounting flange and front cover). This static timing mark should be used as a reference. If timing mark is not present on mounting flange, scribe a line to assist in how far injection pump needs to be rotated. To check and adjust injection timing, perform the following procedure.

Start engine and allow it to reach normal operating temperature. Connect scan tool to Data Link Connector (DLC). Set scan tool to OUTPUT TEST/INJ PUMP mode. Activate TDC TIME SET. The DES INJ TIME value will read zero.
NOTE: If engine stalls when TDC TIME SET is activated, turn engine off. Loosen injection pump nuts. Slightly rotate injection pump toward driver's side of vehicle. Tighten injection pump nuts. Repeat step.
With engine running at idle, ensure ACT INJ TIME displays 3.5 degrees. If timing needs adjustment, turn engine off. Adjust injection pump. A.039" (1.0 mm) pump movement equals about a 2 degree timing change.