35462 Force WASHER-THROTTLE CONTROL

Introduction
The Hydraulic Electronic Unit Injector (HEUI) pump that is used on all C7, C-9 and C9 engine models has received multiple improvements over the course of 2007. This special instruction gives a brief description of the improvements, the resolutions of the improvements, and the part number effectivity of each improvement.The First Improvement
Changes have been made to the control valve and the internal pin for the control valve on the HEUI pump.
Investigation of returned HEUI pumps from the field identified the formation of flat spots on the steel ball that is used in the control valve. The cause of the flat spots has been determined as abrasive wear and impact with the stainless steel pin in the control valve.
The main symptom that was felt by the operator was consistent with unstable engine speed.
The steel ball was changed to a ceramic material and the stainless steel pin was changed to a more durable material in order to resist abrasion.
The change is effective with the following part numbers: 304-0677, 304-0678, 304-0675, 304-0676, 304-0607, 304-0674, 304-0680, 304-0622 and 304-0610.
Illustration 1 g01621580
(1) Location of the steel pin and ball. The Second Improvement
The diameter of the center shaft was increased by two millimeters.
Investigation of returned HEUI pumps revealed that the tapered roller bearing that is internal to the pump was spalling causing metallic debris to be introduced into the entire HEUI system.
Symptoms of this situation were usually a misfire. This was due to the metallic debris that gets into the oil passages of the HEUI fuel injector. Then, a blockage is caused in the oil that is needed in order to inject the fuel. This would result in a misfire.
An additional two millimeters of material has been added to the end of the center shaft. The improvement will strengthen the shaft on the surface for the tapered roller bearing.
This change is effective with the following part numbers: 304-0677, 304-0678, 304-0675, 304-0676, 304-0607, 304-0674, 304-0680, 304-0622 and 304-0610.
Illustration 2 g01621587
(2) Location of added material on the center shaft. The Third Improvement
An additional six millimeters of material has been added to the center shaft in order to create the design of a step shaft.
The symptoms that are addressed by this improvement are the symptoms that are addressed by the second improvement.
This improvement was deemed as a permanent corrective action for the issue of the spalling of the tapered roller bearing and generating metallic debris that entered the HEUI system. The step shaft design eliminated the deflection of the shaft, which was causing uneven loading on the bearing surface and the loss of material.
The change is effective with the following part numbers: 312-0675, 312-0676, 312-0607, 312-0674, 312-0677, 312-0622, 312-0678, 312-0610 and 312-0680
Illustration 3 g01621589
(3) Location of the center shaft that has the step shaft design. Note: Refer to Special Instruction , REHS3819 for extra troubleshooting information and a cleaning procedure for the HEUI fuel system. The Fourth Improvement
The process of crimping has been improved for the connector inside the pump.
The electrical coil inside the pump body did not have an optimum crimp between the wire and the connector. The temperatures and vibrations inside the pump caused the electrical connection to intermittently become faulty.
The symptoms are related to this issue: fluttering of the engine, erratic injection actuation pressure and high current of injection actuation pressure.
The process of crimping has been improved in order to provide a near perfect crimp between the wire and the connector.
This change is effective with part numbers: 319-0607, 319-0675, 319-0676, 319-0677, 319-0678, 319-0622, 319-0674, 319-0610 and 319-0680.