12619 Mercruiser MOUNT, RUBBER

Troubleshooting
Troubleshooting can be difficult. The TROUBLESHOOTING INDEX gives a list of possible problems. To make a repair to a problem, make reference to the cause and correction on the pages that follow.This list of problems, causes, and corrections will only give an indication of where a possible problem can be, and what repairs are needed. Normally, more or other repair work is needed beyond the recommendations in the list.Remember that a problem is not normally caused only by one part, but by the relation of one part with other parts. This list is only a guide and can not give all possible problems and corrections. The serviceman must find the problem and its source, then make the necessary repairs.Troubleshooting Index
1. Engine Will Not Turn When Start Switch Is On.2. Engine Will Not Start.3. Engine Misfires or Runs Rough.4. Stall at Low rpm.5. Sudden Changes In Engine rpm.6. Not Enough Power.7. Too Much Vibration.8. Loud Combustion Noise.9. Valve Train Noise (Clicking).10. Oil In Cooling System.11. Mechanical Noise (Knock) In Engine.12. Fuel Consumption Too High.13. Loud Valve Train Noise.14. Too Much Valve Lash.15. Valve Rotocoil or Spring Lock is Free.16. Oil at the Exhaust.17. Little or No Valve Clearance.18. Engine Has Early Wear.19. Coolant In Lubrication Oil.20. Too Much Black or Gray Smoke.21. Too Much White or Blue Smoke.22. Engine Has Low Oil Pressure.23. Engine Uses Too Much Lubrication Oil.24. Engine Coolant Is Too Hot.25. Starter Motor Does Not Turn.26. Alternator Gives No Charge.27. Alternator Charge Rate Is Low or Not Regular.28. Alternator Charge Is Too High.29. Alterntor Has Noise.30. Exhaust Temperature Is Too High.Engine Crankshaft Will Not Turn When Start Switch Is On Engine Will Not Start Engine Misfires Or Runs Rough Stall At Low RPM Sudden Changes In Engine Speed (rpm) Not Enough Power Too Much Vibration Loud Combustion Noise (Sound) Valve Train Noise (Clicking) Oil In Cooling System Mechanical Noise (Knock) In Engine Fuel Consumption Too High Loud Valve Train Noise Too Much Valve Lash Valve Rotocoil Or Spring Lock Is Free Oil At The Exhaust Little Or No Valve Clearance Engine Has Early Wear Coolant In Lubrication Oil Too Much Black Or Gray Smoke Too Much White Or Blue Smoke Engine Has Low Oil Pressure Engine Uses Too Much Lubrication Oil Engine Coolant Is Too Hot Starter Motor Does Not Turn Alternator Gives No Charge Alternator Charge Rate Is Low Or Not Regular Alternator Charge Too High Alternator Has Noise Exhaust Temperature Is Too High Fuel System
Either too much fuel or not enough fuel for combustion can be the cause of a problem in the fuel system.Many times work is done on the fuel system when the problem is really with some other part of the engine. The source of the problem is difficult to find, especially when smoke comes from the exhaust. Smoke that comes from the exhaust can be caused by a bad fuel injection valve, but it can also be caused by one or more of the reasons that follow: a. Not enough air for good combustion.b. An overload at high altitude.c. Oil leakage into combustion chamber.d. Not enough compression.e. Fuel injection timing retarded.Fuel System Inspection
To check for low fuel pressure, remove the fuel pressure switch or the pipe plug from the fuel filter base. Connect the 8M2743 Gauge from the 5P6225 Hydraulic Test Box to the hole where the switch or plug was removed. Run the engine at high idle and check the fuel pressure reading. The fuel pressure must be a minimum of 15 psi (105 kPa).A problem with the components that send fuel to the engine can cause low fuel pressure. This can decrease engine performance.1. Check the fuel level in the fuel tank. Look at the cap for the fuel tank to make sure the vent is not filled with dirt.2. Check the fuel lines for fuel leakage. Be sure the fuel supply line does not have a restriction or a bad bend.3. Install a new fuel filter. Clean the primary fuel filter.4. Remove any air that may be in the fuel system. Use the priming pump to push the air through the return line to the fuel tank.To remove air from the fuel injection lines, loosen the fuel line nuts 1/2 turn. Move the governor lever to the low idle position. Crank engine with the starter motor until fuel without air comes from the fuel line connections. Tighten the fuel line nuts.Checking Engine Cylinders Separately
An easy check can be made to find the cylinder that runs rough (misfires) and causes black smoke to come out of the exhaust pipe.Run the engine at the speed that is the roughest. Loosen the fuel line nut at a fuel injection pump. This will stop the flow of fuel to that cylinder. Do this for each cylinder until a loosened fuel line is found that makes no difference in engine performance. Be sure to tighten each fuel line nut after the test before the next fuel line nut is loosened. Check each cylinder by this method. When a cylinder is found where the loosened fuel line nut does not make a difference in engine performance, test the injection pump and fuel injection nozzle for that cylinder.Temperature of an exhaust manifold port, when a engine runs at low idle speed, can also be an indication of the condition of a fuel injection nozzle. Low temperature at an exhaust manifold port is an indication of no fuel to the cylinder. This can possibly be an indication of a nozzle with a defect. Extra high temperature at an exhaust manifold port can be an indication of too much fuel to the cylinder, also caused by a nozzle with a defect.The most common defects found with the fuel injection nozzles are:1. Carbon on tip of the nozzle or in the nozzle orifice.2. Orifice wear.
Do not test nozzles