Subaru Robin EX13 - Manual (Page 108)

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9. ORGANIZE
Most people know that engines will require daily and periodic maintenance, but it’s also important
to be aware of the audible and visual signs of unexpected maintenance needs . Operators should
also take into consideration working conditions and how they affect engine performance . Proper
engine storage shouldn’t be overlooked either .
Addressing the small issues early on, making appropriate environmental adjustments and
following storage guidelines will all help prevent engine troubles from creeping up in the future .
9-1 TROUBLESHOOTING
If an engine is experiencing hard starts, check the oil level and add or drain oil until to the proper
crankcase level . Turn the ignition switch to off, pull 5 or 6 times, then turn switch back to on and start
engine normally . Following this extra starting procedure on an EFI engine will ensure the cylinder is not
flooded and/or ensure the fuel system has been purged of excess air .
If an engine is still experiencing hard starts, the valve clearance on the intake and exhaust valves
should be checked and adjusted according to manufacturer specifications . When checking the valve
clearance, position the piston at the top dead center of the compression stroke and ensure the engine
is cold . After the clearance is adjusted, rotate the crankshaft and check the valve clearance again .
A reduction in power often is an indication that the fuel tank outlet filter and/or cylinder head needs to
be inspected and cleaned . Check the oil level and add or drain the oil until to the proper level . Check
the air filter and fuel tank outlet filter as well . Check the fuel pump pulse line for any restriction, air leaks
or damage . Replace as needed . Check the cylinder head’s valves, seats, ports and guides and remove
any carbon or gum deposits from the components .
If the recoil rope hangs loose and doesn’t completely return, it could be a sign that water has intruded
the engine . This indicates the lubricant may have been washed off . Remove the recoil return and apply
additional lubrication to fix the problem . Ignoring the issue can result in a broken rope or eventual
damage to the recoil starter .
Additionally, a loss of power or a smoking engine may signal an internal engine problem . Blue-colored
smoke indicates that the engine is using oil, a problem that tends to be more common on cold days .
Look to see if the breather hoses are plugged and check the piston rings, which may be bad, to
determine the cause of the smoke .
If the smoke is black in color, it typically indicates that the mixture is too rich . Incorrect mixtures of air
and fuel cause the majority of throttle body problems; therefore, it is important to prevent clogged air
passages and fuel passages that keep air and fuel from flowing freely . Check the throttle body for dirty
or defective parts and clean or replace the entire throttle body assembly if needed . Check the throttle
body fuel feed and return lines for any restriction or damage . Replace as needed . A change in elevation
also may cause black smoke, in which case the engine should be modified to handle the difference .
If basic troubleshooting maintenance techniques fail to work, have a trained mechanic conduct a
leakdown test or compression test to determine the cause for any smoking or power reduction .
Like smoke colors, different noises also can indicate specific problems . For instance, if the engine
begins to make a popping noise or backfire, the mixture of fuel and air is likely too lean in the throttle
body . A knocking noise will generally indicate a worn connecting rod, while a tinny or metallic sound
may mean something is loose .