C 20 3/4 Ton Pickup 2WD V8-379 6.2L DSL VIN C FI (1983)
The injection pump cannot be modified on the vehicle. The following procedure should be used:
1.
Remove the injection pump per Service Manual procedures. Be sure to note the relationship of the timing marks on the pump and front
housing. The pump must be reinstalled to its exact previous position.
2.
Send the pump to an ADS (Association of Diesel Specialists) Service Center for the altitude performance adjustment. The ADS Service
Centers will be advised by Stanadyne Corporation Bulletin as to injection pump recalibration procedures.
3.
Reinstall the pump per Service Manual procedure. The pump must be installed to its original timing setting. If the original timing
relationship was not retained, refer to bulletins detailing the timing procedure to follow.
ALTITUDE ADJUSTMENT LABEL
When LOW ALTITUDE vehicles are adjusted for high altitude operation, a SUPPLEMENTAL emission control information label must be
placed next to the existing underhood emission control information label. Wash off the area with soap and water, dry thoroughly, and apply
the new label (P/N 14057201).
The label should be ordered as regular parts and accessories through the General Motors Warehousing and Distribution Division system.
When ordering these labels via rapid entry, use order type CSD. Orders also may be placed on a PC 66 and mailed directly to GMWDD,
6060 West Bristol Road, Flint, Michigan 48554, attention Ship Direct Department.
After performing these adjustments, dealers should advise customers that, IF THE VEHICLE IS RETURNED TO CONTINUOUS, LOW
ALTITUDE OPERATION, THE PUMP MAY BE RECALIBRATED TO LOW ALTITUDE SPECIFICATION PER THE ABOVE
PROCEDURE AND THE SUPPLEMENTAL LABEL REMOVED.
Vehicles designed for principal use at high altitude perform satisfactorily at low altitude without excessive smoke levels and need not be
adjusted for extended operation at low altitude.
Technical Service Bulletin # 83I41VI
Date: 830201
Diesel Engine - Excessive Exhaust Smoke, Rough Running
Number:
83-I-41
Section:
VI
Date:
FEB., 1983
SUBJECT:EXCESSIVE EXHAUST SMOKE ROUGH RUNNING DIESEL ENGINES 1980-83 PASSENGER CAR
TO:
ALL CHEVROLET DEALERS
Diesel engines that exhibit excessive exhaust smoke and run rough after cold starting may usually be corrected by dynamic timing. If timing
does not correct this condition check the housing pressure cold advance (HPCA) for proper operation (1981 thru 1983 models). Also check
for a sticking advance piston in the injection pump (1980 thru 1983 models).
To check for a sticking advance piston, push in on the bottom of the face cam lever on the right side of the injection pump. This will retard
the timing and cause the engine to run rough if the advance piston is free. If there is no change, the piston is sticking.
Technical Service Bulletin # 83I16
Date: 821201
Diesel Engine - High Altitude Adjustment
Number:
83-I-16
Section:
VI
Date:
Dec. 1982
Subject:
HIGH ALTITUDE ADJUSTMENT - 1983 "C-K-P-G" TRUCKS WITH 6.2L DIESEL ENGINE LL4 (HEAVY-DUTY) OR LH6 (LIGHT
DUTY) EMISSIONS
TO:
ALL CHEVROLET DEALERS
These adjustments are considered altitude performance adjustments and apply only to in-use vehicles. They should not be used to modify
vehicles prior to sale.
1983 trucks equipped with the 6.2L diesel engine for low altitude operation may be modified if operation is changed to high altitude for an
extended period or permanently. Dealers in high altitude areas should encourage owners who have moved to high altitude counties to
purchase the service adjustment procedure outlined below which is considered an owner maintenance expense. High altitude is defined as
