Service Procedure
INSPECTION INSTRUCTIONSInspect the fuel injection pump model number and serial number located on the fuel injection pump identification plate. The fuel injection pump must be retimed and the PROM replaced if either of the following is true:
- The model number is DB-2329-4894 and the serial number is less than 6633950, or
- The model number is DB-2829-4895 and the serial number is less than 6617332.
If neither of the above are true, only the PROM must be replaced.
PROM REPLACEMENT
(Required For All Vehicles)
1. Disconnect negative battery cable.
2. Remove glove box insert.
3. Remove ECM.
4. Remove ECM access cover
5. Remove PROM from ECM.
6. Install new PROM and reinstall access cover.
7. Reinstall ECM.
8. Reinstall glove box insert.
9. Reconnect negative battery cable.
RETIMING PROCEDURE
(Required Only For Some Vehicles - See Inspection Procedure)
Notice:
Perform this retiming procedure with the engine off.
1. Loosen 3 pump retaining nuts and advance (toward driver side of vehicle) fuel injection pump timing 1 mm (equivalent to 2 degrees of crankshaft rotation).
2. Stamp a new timing line on front cover to match timing line on iniection nump flange.
Also, stamp a letter "O" across the joint flange of both the engine timing cover and the injection pump to show the correct timing by alignment of both halves of the letter "O".
Notice:
Page 6C2-8 of the 1991 C/K Truck Service Manual provides further details regarding this procedure.
FOR ALL VEHICLES
Install Campaign Identification Label when all campaign repairs are completed.