Unit Injection System

The Fuel System:

Unit Injection System

This system consists of injectors, fuel supply pump, fuel oil filter, and the fuel oil manifold.

Fuel is drawn from the supply tank through the primary filter by the fuel supply pump. From the pump, fuel is forced through the secondary filter and to the fuel intake manifold which supplies the injectors. Surplus fuel, flowing through the injectors, is returned through the fuel outlet manifold to the supply tank.

Unit injectors combine the injection pump, the fuel valve, and the nozzle in a single housing to eliminate the high-pressure line.

These units provide a complete and independent injection system for each cylinder and are mounted in the cylinder head, with their spray tips slightly below the top of the inside surface of the combustion chambers. U-clamps, bolted to the cylinder head and fitting into a machined recess in each side of the injector body, hold the injector in place in a water-cooled copper tube which passes through the cylinder head. The tapered lower end of the injector seats in the copper tube, forming a tight seal to withstand the high pressures inside the cylinder.

Fuel oil is supplied to the injector at about 20 PSI and enters the body at the top through the filter cap. After passing through the fine-grained filter element in the inlet passage, the fuel oil fills the annular (ring-shaped) supply chamber between the bushing and split deflector. The plunger operates up and down in the bushing, the bore of which is connected to the fuel supply in the annular chamber by two funnel-shaped ports, one on each side at different heights.

Injector rocker arms

The injector arms are actuated through pushrods from the engine camshaft. The motion of the injector rocker arm is transmitted to the plunger by the follower, which bears against the return spring. In addition to this reciprocating motion, the plunger can be rotated in operation around its axis by the gear, which is in mesh with the control rack.

Each injector control rack is connected by a joint to a lever on a common control tube which, in turn, is linked to the governor and throttle.

FIGURE 15. DISTRIBUTOR INJECTION SYSTEM.

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Article Pages
1. Introduction
2. Introduction To Gasoline
3. Fuel System Introduction
4. Fuel Tanks
5. Fuel Filters
6. Fuel Pumps
7. Fuel Tank Ventilation Systems
8. Intake Manifold
9. Air Filters
10. Principles Of Carburetion
11. Basic Carburetor Construction
12. Systems Of The Carburetor
13. Fuel Injection Introduction
14. Multiple Unit Injection Pump System
15. Unit Injection System
16. Distributor Injection System
17. Pressure Time System
18. Supply Pumps
19. NEED TO MOVE ARTICLE
20. Fuel System Inspection
21. Air Induction
22. Supercharging
23. Supercharger Systems And Pumps
24. Rotating Compressors
25. Inspection Of Compression Ignition Engine Fuel Systems
26. Inspection Of Fuel System Components
27. Inspecting A Malfunctioning Vehicle
28. Introduction To Diesel Engine Fuel Systems
29. Introduction To Diesel Fuel
30. Introduction To Diesel Fuel System Design
31. Diesel Engine Combustion Chamber Design
32. Diesel Engine Fuel Injection System
33. Diesel Engine Fuel Pumps
34. Diesel Engine Governors
35. Diesel Fuel Injection Pump Timing
36. Cold Weather Starting Aids
37. Diesel Fuel Filters
38. Diesel Engine Brake Systems

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