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Kohler Magnum 18 twin backfire


Engine ran strong without problems for years,then was running only on 1 cylinder.I removed head from non-firing cylinder and verified valve operation and no carbon buildup.replaced head and backfiring occurs. Engine will not start with 1 sparkplug removed ,or with both installed.Replaced plugs with new,and tried with old. No difference! Any ideas?

Tom Schaech

Last Subscription Date
Several things need to be assessed here to determine the source of the problem. Do you have (or had) spark at both plugs? Did you perform a compression test on each cylinder to determine the PSI on the cylinders? Check ground wires for continuity? Is it backfiring when shutting off? These have anti-fire solenoids on the fuel bowls that have been a perennial problem-to the point where Kohler says to shut the engine off at full throttle. One coil or two? I've seen them go bad, especially if the cooling fins get clogged up and overheat the coil.



Tom,thanks for your checklist of suggestions. I opened both Valve covers and found the valve spring guide on one intake valve broken and valve retainer lying in valve chamber! Next I will check to see why the breakage occurred.