25299 Mercury SCREW, CHOKE SOLENOID ATTACHING (3/4")

Fuel leaked or spilled onto hot surfaces or electrical components can cause a fire. To help prevent possible injury, turn the start switch off when changing fuel filters or water separator elements. Clean up fuel spills immediately.
Personal injury or death can result from improperly checking for a leak.Always use a board or cardboard when checking for a leak. Escaping air or fluid under pressure, even a pin-hole size leak, can penetrate body tissue causing serious injury, and possible death.If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury.
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Ensure that all adjustments and repairs that are carried out to the fuel system are performed by authorized personnel that have the correct training.Before beginning any work on the fuel system, refer to Operation and Maintenance Manual, "General Hazard Information and High Pressure Fuel Lines" for safety information.Refer to Systems Operation, "Cleanliness of Fuel System Components" for detailed information on the standards of cleanliness that must be observed during all work on the fuel system.
Leaks can be detected in the high-pressure fuel system by checking the following locations:Isolate the leakage to a specific portion of the fuel rail:
Illustration 1 g02467128
Fuel rails for the C175 engines (typical example)
(1) Plug
(2) Line fitting
(3) Check valve
On the right side of the engine, remove plug (1) from the drain port at the rear of the fuel rail.
On the left side of the engine, disconnect line fitting (2) from the drain port at the rear of the fuel rail.
Illustration 2 g02469816
Location of the drain port in the outlet manifold at the high-pressure fuel pump (right side engine view)
(4) Plug
Remove plug (4) from the outlet manifold at the high-pressure fuel pump.
Start the engine and run the engine. Check each of the drain ports for fuel leakage. Also, check the loose end of the fuel return line for leakage.If fuel leakage is found, the location of the leak will be an indication of the failed component in the fuel system:
If leakage is present at the loose end the fuel return line, check valve (3) has failed. Replace the check valve.
If leakage is present at the drain port on the right side of the engine, check the right fuel rail extensively for leaks.
If leakage is present at the drain port on the left side of the engine, check the left fuel rail extensively for leaks.
If leakage is present at the drain port at the high-pressure fuel pump, check for a leak in the fuel supply line. The leak will be located between the fuel line connection at the pump and the fuel line connection at the right fuel rail.
If leakage is present at multiple locations, check the components that are associated with each location extensively for leaks.
Identify leakage at the left fuel rail or the right fuel rail:
Illustration 3 g02469957
(5) Plug Note: There is a plug at the fuel supply connection for each injector.
For the fuel rail that was identified in Test Step 4 as leaking, remove plug (5) from the fuel supply connections for each of the injectors.
Start the engine and run the engine.
Check the open drain ports at each cylinder for leakage. Record the results.
Leakage near assembled joints in the fuel line may be caused by a leak in the connecting joints or other fuel system components. Leakage at the seal joints for the fuel line connections at the injectors is highly unlikely. Use the following information to identify other possible leak paths on the fuel rail:
Illustration 4 g02469977
Location of the pressure sensor for the high-pressure fuel system (left fuel rail)
(6) Fuel pressure sensor
If the drain ports on either side of the fuel pressure sensor (6) are leaking, the leak may be in the seal joint. Check the seal joint between the pressure sensor and the fuel rail for a problem.
Illustration 5 g02469983
Location of the crossover tube for the high-pressure fuel system (rear engine view)
(7) High-pressure fuel line that connects the fuel rails
If the leak is coming from the drain ports near crossover tube (7), there, may be a problem in the connecting joints. Check for a problem in the joints between the crossover tube and the fuel rail. Show/hide t