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one cylinder not firing

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Jwemcc
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2017/10/11 16:31:31 (permalink)
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one cylinder not firing

20.5 horsepower IC Platinum turbo cool. Put two new plugs in it started it up could not get full rev out of the motor pull both plugs one is hot one is cold one is extremely blackened and Rich wet and the other is cold with just wet gas on it. Both cylinders get spark when spark plug is pulled and grounded with motor turning over. Obviously the one cylinder is not firing but I'm not sure where to start can anybody help me out.
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    AVB
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    Re: one cylinder not firing 2017/10/12 08:52:25 (permalink)
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    Just because spark can jump the gap out the engine does mean it is strong enough to do it under compression. When a homeowner has twin cylinder they can simply swap plug to see if it is simply a bad plug and yes new plugs can be bad straight out of the box. If it not the problem with you may have a lost compression on the side not firing. This can either valve not fully closing or cylinder problems.
     
    The professional tech can use a spark gap tester that has .166" gap to see if the ignition is able to produce the 13,000 volts that it takes jump the gap. Most plugs when cold will need 10,000 volts to jump a 0.30" gap so you would a little voltage to spare which helps with worn plugs as they take more the jump the gap.
     
    I have had several engine with various levels of plug failures where they could easily spark out the compression environment.
    post edited by AVB - 2017/10/12 08:54:06
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    Roy
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    Re: one cylinder not firing 2017/10/12 11:28:47 (permalink)
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    Can you give us the engine numbers so we have a better idea of what you are looking at? You need o do a compression test or better yet a leak own test to determine why that cylinder is not firing.
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