809881A 1 Mercury VELOCITY VALVE KIT

Fuel System Inspection
A problem with the components that send fuel to the engine can cause low fuel pressure. This can decrease engine performance.
Check the fuel level in the fuel tank. Inspect the cap for the fuel tank. Make sure that the vent is not filled with dirt.
Check the fuel lines for fuel leakage. Make sure that none of the fuel lines have a restriction or a faulty bend.
Install a new fuel filter. Clean the primary fuel filter.
Remove any air that may be in the fuel system.If there is air in the fuel system, use the priming pump to open the drain valve on the fuel injection pump housing. Drain the fuel system until fuel without air flows from the drain line.Fuel Transfer Pump
When the engine is operating at full load speed, the fuel transfer pump receives fuel from the primary fuel filter. Fuel flows through the ECM and flows through the secondary fuel filters to the fuel injection pump.Use the following steps to check the fuel transfer pump pressure.
Disconnect the fuel line from the filter at the fuel injection pump housing inlet.
Install a tee at the inlet.
Connect the fuel line to the tee.
Connect a pressure gauge to the tee.
Start the engine.
Fuel is delivered to the fuel pump housing at approximately 414 kPa (60 psi) at full load speed.If the fuel pressure is not to specifications, stop the engine. Replace the primary fuel filter and replace the secondary fuel filters. Make sure that the fuel lines and the hoses are not plugged or damaged.Start the engine and check the fuel pressure. If the fuel pressure is not at specifications, repair the fuel transfer pump or replace the fuel transfer pump.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 the roughest speed.
Loosen the fuel line nut at a fuel injection pump. This will stop the flow of fuel to that engine cylinder.After you shut off an engine cylinder's fuel flow, the engine should run more roughly.
Tighten the fuel line nut.
Repeat this maneuver 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.
Test the fuel injection valve.When an engine runs at low idle rpm, the temperature of an exhaust manifold can also indicate the condition of a fuel injection valve. A low temperature indicates that no fuel is reaching the cylinder. This can possibly signify that the fuel injection valve 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 injection valve has a defect.The most common defects on fuel injection valves include the following defects:
Any carbon on the tip of a nozzle
Any carbon in the nozzle orifice
Orifice wear
Dirty nozzle screenTesting Fuel Injection Nozzles
The injectors must be off of the engine before being tested.Note: Refer to Special Instruction, SEHS7292, "Use Of 5P-4150 Nozzle Assembly" for more information.Fuel Injection Lines
Fuel from the fuel injection pumps is sent through the fuel injection lines to the fuel injection valves.Each fuel injection line of an engine has a special design. Each fuel injection line must be installed in a certain location. When fuel injection lines are removed from an engine, put identification marks or put tags on the fuel lines as the lines are removed. This will allow the lines to be installed in the correct location.The nuts that hold a fuel injection line to an injection valve and to an injection pump must be kept tight. Tighten the fuel line nuts to 40 7 N m (30 5 lb ft).Fuel Bypass Valve
The fuel bypass valve controls fuel pressure to the fuel injection pump. At full speed, the pressure is limited to 230 35 kPa (33 5 psi).Finding the Top Center Position for No. 1 Piston
Table 1
Tools Needed    
9S-9082     Engine Turning Tool     1    Note: The starting position for all timing procedures is with the No. 1 piston at the top center position on the compression stroke.
Illustration 1 g00361852
Locating the top center position (typical example) (1) The storage location for the timing bolt. (2) Plug. (3) Bolt. (4) Cover.
Remove the timing bolt (1), the bolt (3), and the cover (4) .
Remove the plug (2) .
Illustration 2 g00361853
9S-9082 Engine Turning Tool is installed. (1) The installed timing bolt. (5) 9S-9082 Engine Turning Tool .
Install 9S-9082 Engine Turning Tool (5) in the housing.
Once plug (2) has been removed, insert the timing bolt (1) through the hole. Hold the timing bolt (1) against the flywheel.
Turn the flywheel in the direction of normal engine rotation until the timing bolt engages with the threaded hole. The No. 1 piston is at the top center position on the engine.Note: If the flywheel is turned beyond the point of engagement, the flywheel must be turned in the direction that is opposite of normal engine rotation. Turn the flywheel by approximately 30 degrees. Then turn the flywheel in the direction of normal engine rotation until the timing bolt engages with the threaded hole. When the No. 1 piston is at the top center position, this procedure will remove the play from the gears.
Illustration 3 g01246025
Cylinder and valve location (A) Inlet. (B) Exhaust. (C) Fuel injection pumps.
Remove the left front valve cover. Look at the valves of No. 1 cylinder. The valves will be closed if the No. 1 piston is on the compression stroke. You can move rocker arms up and down with your hand. If the No. 1 piston is not on the compression stroke, perform the following steps.
Remove the timing bolt fr