Checking/Adjusting Injection Timing
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 1996 GMC Vandura Special, 1996 GMC Vandura, 1996 GMC Savana Special, 1996 GMC Savana Camper Special, and 1996 GMC Savana. However, it is still accessible from the selected car via links, so may be relevant.
Original factory injection pump timing is marked with a static timing mark, a line scribed across both the pump mounting flange and the 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.
- Start and warm engine to normal operating temperature. Connect Tech 1 scan tester. Set scan tester to OUTPUT TEST/INJ PUMP mode. Activate TDC TIME SET. The DESIRED INJ TIM 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 1).
- Ensure engine is running, then check "MEASURED INJ TIM" for proper timing specification. See DIESEL INJECTION PUMP TIMING table. If timing needs adjustment, turn engine off to avoid engine damage, then adjust injection pump. A 1-mm pump movement equals about 2 degrees timing.
DIESEL INJECTION PUMP TIMING (DEGREES BTDC @ RPM)
| Application | Man. Trans. | Auto. Trans. |
|---|---|---|
| 6.5L (VIN F, P & S) | 3.5 @ Idle | 3.5 @ Idle |