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Look for corroded elements, loose wires, stuck buttons, etc. Check for any loose connections and frayed wiring. Make sure the area around the generator is clean, and if the generator has sucked in any dirt or leaves make sure to clean out the area. Debris getting into an alternator is the #1 way of destroying a perfectly good generator! Seek professional advice if you're not sure what to do. It is best to be safe! Also check the battery's voltage. It is generally best to replace your battery every 2-3 years. ) following the manufacturer's instructions. This doesn't need to be done each 6 months; rather this is an annual task whether or not the generator has been operated. Record the yearly change in the record book so that you are reminded each time when it is due. Make sure that the oil level is adequate and top up if needed. Air cooled machines should have their oil replaced every 30-40 hours of run time. Liquid cooled machines should have their oil replaced every 100 hours of run time. MAKE SURE TO USE SYNTHETIC OIL IN AIR COOLED MACHINES! For the dollar fifty price tag of a spark plug, it is generally best to just replace the spark plugs annually. Note that bolts on the generator will tend to loosen after reasonable usage; this is usual wear and tear caused by the vibrations. Check the gasket head and piston for solid condition; replace if worn or cracked. Gasoline that is simply sitting in the generator loses its effectiveness after half a year when not used. You have several alternatives here:  Bleed the fuel and replace it; dispose of properly Keep regularly used fuel for general farm/household use in fuel suitable containers and top up when needed Add fuel stabilizer available from gas stations or hardware stores; follow manufacturer's instructions If you are using a generator as a home standby solution, you should really consider a natural gas or liquid propane generator. These generators do not have any fuel maintenance, other than to make sure your LP tank has fuel in it! It is best if a certified generator technician makes these checks:  Fuel pump    {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/6\/67\/Maintain-a-Generator-Step-10Bullet1.jpg\/v4-460px-Maintain-a-Generator-Step-10Bullet1.jpg","bigUrl":"\/images\/thumb\/6\/67\/Maintain-a-Generator-Step-10Bullet1.jpg\/aid678918-v4-728px-Maintain-a-Generator-Step-10Bullet1.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}  Turbocharger    {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/9\/91\/Maintain-a-Generator-Step-10Bullet2.jpg\/v4-460px-Maintain-a-Generator-Step-10Bullet2.jpg","bigUrl":"\/images\/thumb\/9\/91\/Maintain-a-Generator-Step-10Bullet2.jpg\/aid678918-v4-728px-Maintain-a-Generator-Step-10Bullet2.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}  Injectors    {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/e\/e9\/Maintain-a-Generator-Step-10Bullet3.jpg\/v4-460px-Maintain-a-Generator-Step-10Bullet3.jpg","bigUrl":"\/images\/thumb\/e\/e9\/Maintain-a-Generator-Step-10Bullet3.jpg\/aid678918-v4-728px-Maintain-a-Generator-Step-10Bullet3.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"}  Automatic voltage regulator    {"smallUrl":"https:\/\/www.wikihow.com\/images\/thumb\/4\/48\/Maintain-a-Generator-Step-10Bullet4.jpg\/v4-460px-Maintain-a-Generator-Step-10Bullet4.jpg","bigUrl":"\/images\/thumb\/4\/48\/Maintain-a-Generator-Step-10Bullet4.jpg\/aid678918-v4-728px-Maintain-a-Generator-Step-10Bullet4.jpg","smallWidth":460,"smallHeight":345,"bigWidth":"728","bigHeight":"546","licensing":"<div class=\"mw-parser-output\"><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"https:\/\/creativecommons.org\/licenses\/by-nc-sa\/3.0\/\">Creative Commons<\/a><br>\n<\/p><p><br \/>\n<\/p><\/div>"} If a generator is not used on a regular basis, it is recommended that you fire it up at quarterly intervals to ensure that its workings run smoothly. At the very least, start it after each six monthly maintenance, twice. First check is to see that it is starting OK, second check is to ensure that it will keep starting OK.

Summary:
Start by checking the overall condition of the generator. Fix anything loose, stuck, or fraying. Check the distilled water in the battery; top up if needed. Change the lubricant oil and filters (super, by-pass, etc. Clean the spark plugs. Check the bolts. Check the fuel. Check that the following items are properly calibrated annually or biannually, depending on usage patterns. Start up the generator regularly.