F 250 4WD Pickup V8-6.9L DSL (1983)
Injection Timing: Technical Service Bulletins
Dynamic Injection Timing - Service Tips
Article No. 83-12-16
DIESEL (6.9L) - SERVICE TIPS FOR CHECKING AND SETTING DYNAMIC INJECTION TIMING
LIGHT TRUCKS 1983 E & F SERIES
Some service tips for checking and setting dynamic injection timing on the 6.9L diesel engine are listed below:
1.
When checking or setting dynamic injection timing on the 6.9L engine, it is mandatory that the engine be stabilized at normal operating
temperature (19~ F - 212~ F). This temperature is needed to ensure proper fuel ignition in the pre-combustion chambers. If the engine temperature
is below 192~ F, fuel ignition is delayed and the dynamic timing meter (Rotunda 78-0100) will record an incorrect dynamic injection timing value.
Specified timing is shown in the following chart:
SPECIFIED DYNAMIC TIMING ALTITUDE
Fuel Cetane Value
0-3000 Ft.*
Above 3000 Ft.*
38-42
6~ATDC
7~ATDC
43-46
5~ATDC
6~ATDC
47 or Greater
4~ATDC
5~ATDC
*Installation or resetting tolerance for dynamic timing is + 1~. Service limit is + 2~.
Dynamic engine timing is also affected by the fuel quality and altitude. The dynamic timing method observes "beginning of fire" in the pre-combustion
chamber through the luminosity probe. "Beginning of fire" occurs some period of time after the fuel is injected into the pre-combustion chamber. The
period of time between beginning of injection and "beginning of fire" is known as ignition lag. Ignition lag is a characteristic of all diesel engines.
Diesel fuel cetane is a rating of the ability of fuel to ignite under compression ignition conditions. High cetane fuels will ignite sooner than will low
cetane fuels. This difference in ignition lag results in different timing readings when, in fact, the mechanical timing for beginning of fuel injection has not
changed. What is now different is the amount of time it takes for the fuel to begin burning after it is injected.
The Dynamic Timing Specification Chart takes cetane value as well as altitude into consideration. For this reason, the chart, as well as the cetane tester,
must be used when evaluating the timing of a 6.9L diesel.
2.
Prior to checking the dynamic timing with the Rotunda 78-0100 Dynamic Timing Meter, perform the meter operation check as identified in the
instruction manual included with the meter.
3.
Effective with the release of the C-6 transmission for the 6.9L diesel engine, a revised fast idle bracket and solenoid are installed on the fuel
injection pump. Removal of the revised bracket and solenoid is necessary when setting or adjusting injection pump timing. The removal is
required to provide access clearance for the injection pump wrench T83T- 9000-B and the pump rotating tool T83T-9000-C.
NOTE:
The fast idle bracket will also be incorporated on manual transmission vehicles later in the model year.
After removal of the bracket from the injection pump, the dynamic timing can be set or adjusted as identified on Page 25-8 of the 1983 Engine Emissions
Manual. With the timing procedure completed, reinstall the bracket and solenoid and tighten the fasteners to 9.5 N-m (7 ft.lbs.).
OTHER APPLICABLE ARTICLES: 83-10-19; 83-3-21
WARRANTY STATUS: "INFORMATION ONLY"
