FO16143 Force THROTTLE SHAFT RETURN SPRING

Fuel System Inspection
Remove the 1/8 inch Pipe Plug from the fuel filter base in order to check for low fuel pressure. Use a pressure gauge. Install a 1U-5470 Engine Pressure Group .Run the engine at high idle and check the fuel pressure. The fuel pressure must be at least 105 kPa (15 psi).A problem with the components that send fuel to the engine can cause low fuel pressure. This can decrease engine performance. To inspect the fuel system, follow this procedure:
Check the fuel level in the fuel tank. Ensure that the vent in the fuel cap is not filled with dirt.
Check all fuel lines for fuel leakage. The fuel lines must be free from restrictions and faulty bends. Verify that the fuel return line is not collapsed.
Install a new fuel filter.
Cut the old filter open with the 175-7546 Oil Filter Cutter. Inspect the filter for excess contamination. Determine the source of the contamination. Make the necessary repairs.
Service the primary fuel filter (if equipped).
Operate the hand priming pump (if equipped). If excessive resistance is felt, inspect the fuel pressure regulating valve. If uneven resistance is felt, test for air in the fuel. Refer to Testing and Adjusting, "Air in Fuel - Test" for more information.
Remove any air that may be in the fuel system. Refer to Testing and Adjusting, "Fuel System - Prime".Follow these steps when you drain air from the fuel injection lines:
The fuel injection nozzles can be permanently damaged by twisting if only one wrench is used to loosen or tighten the fuel line nuts.Use one wrench to hold the nozzle and another to loosen the nut.
Loosen the fuel line nuts on the fuel injection nozzle by 1/2 turn.
Move the governor lever to the LOW IDLE position.
Crank the engine with the starting motor until fuel without air flows from the fuel line connections.
Tighten the fuel line nuts.Note: The fuel priming pump will not provide enough pressure for pushing fuel through the reverse flow check valves in the fuel injection pumps.Checking Engine Cylinders Separately
If any of the following conditions occur, check the individual engine cylinders:
The engine runs rough.
The engine misfires.
The exhaust system blows out black smoke.Use this procedure to check the engine cylinders separately:
Run the engine at a speed that gives the maximum misfiring or rough running.
The fuel injection nozzles can be permanently damaged by twisting if only one wrench is used to loosen or tighten the fuel line nuts.Use one wrench to hold the nozzle and another to loosen the nut.
Then, loosen a fuel line nut on the fuel injector nozzle for each cylinder one at a time. This will stop the flow of fuel to that engine cylinder.When a fuel line nut is loosened, the misfiring or rough running should increase.
Tighten the fuel line nut.
Repeat 1 through Step 3 with each engine cylinder in sequence until you discover a loosened fuel line that does NOT affect the engine's performance.
When you find the engine cylinder that does NOT affect the engine's performance, perform the following operations:
Test the fuel injection pump for that cylinder.
Test the fuel injector nozzle.When an engine runs at low idle speed, the temperature of an exhaust manifold can indicate the condition of a fuel injector nozzle. A low temperature indicates that no fuel is reaching the cylinder. This can possibly signify that the fuel injector nozzle has a defect.When an engine runs at low idle rpm and the temperature of an exhaust manifold is at an extra high temperature, too much fuel is probably flowing into the engine cylinder. This can also signify that the fuel injector nozzle has a defect.The most common defects on fuel injector nozzles include the following defects:
Plugging or blocking by carbon at the orifice of a fuel injector nozzle
Orifice wear due to abrasive particles in the fuel
Wear from a wire brush on the fuel injector nozzle's tipRefer to Special Instruction, SEHS8149 for the procedure for checking the temperatures in the exhaust manifold port.Fuel Injection Lines
Fuel from the Fuel Injection Pumps to the Fuel Injector Nozzles
Fuel from the fuel injection pumps flows to the fuel injector nozzle through fuel injection lines.When fuel injection lines are disconnected, always place caps on the end and plugs on the end. This will keep the dirt out of the fuel injection lines. When fuel injection lines are installed, ensure that all clamps and all dampers are returned to original positions.The nuts that connect a fuel injection line to both the fuel injector nozzle and the fuel injection pump must be tightened to the correct torque.If the nuts are not tightened to the proper torque, the following problems may occur:
If the nut is loose, fuel will leak from the connection.
If the nut is too tight, the inside diameter of the line will become smaller. This causes a restriction to the fuel flow in the fuel line.Use a torque wrench and a 5P-0144 Fuel Line Socket to tighten the fuel injection line nut to a torque of 41 7 N m (30 5 lb ft).
Fuel injection lines that are bent, damaged, or rubbing against surfaces can leak and cause a fire. Replace any lines that are bent, or damaged when tightened to the correct torque. Correct or replace any lines that are rubbing when tightened to the correct torque.
Checking the Plunger and Lifter of an Injection Pump
Note: If the pump plunger is worn, good contact will not occur. A pump plunger must be replaced if the pump plunger is damaged. A lifter must also be replaced if the lifter is worn. There are no different sizes of spacers that are available so you can adjust the timing dimension of the fuel injection pumps. Since there is no possible adjustment to the timing dimension, no off-engine adjustment procedure for the engine lifter setting procedure is available.If the pump plunger on the fuel injector is worn, the lifter may also be worn. If either of these conditions exists, good contact will not be possible. Replace the lifters soon after you see wear on the pump plunger.