15.5 kohler runs rough when hot

dieseldan

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Guys i just bought this 1995 craftsman mower that is in mint shape. It has a 15.5 kohler and hydro drive. It runs great until about 1/2hr into mowing it slowly starts to act like its running out of fuel. Mine has the rear mounted fuel tank with the mechanical fuel pump. I thought it was the pump so i replaced it along with the fuel filter. That made no change, so i drained the tank and cleaned that. No change. It has good spark even when its hot. I was ruling out the coil cause it doesn't just shut off, but slowly starts to spit and sputter. It will idle just fine. Do you guys have any other ideas before i replace the coil? It still seems fuel related.:frown:
 

KennyV

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If someone replaced the fuel cap with an non-vented cap... it will do what you are describing... loosen the cap and see if you can continue to mow..
You can also substitute another fuel at the time you loose power... Use WD40, if you are creative you can rig a small tube into your air cleaner directly into the carb intake... when you loose power try a good blast of WD through the long tube... If you are in fact short of fuel it will respond.
:smile:KennyV
 

dieseldan

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Thanks Kenny. I have tried loosening the cap with no luck and i have also cleaned the carb. I will try the wd-40 trick. I appreciate the help!
 

KennyV

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There is also a possibility that you are having a valve problem when it gets hot... KennyV
 

dieseldan

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I was thinking about that. My brothers 17.5 briggs will do that. It will almost die when it gets warmer. The nuts on the rockers come loose and back off the mounting studs which then won't operate the valves. His briggs is an 09 and will already do that, it pukes oil out the exhaust valve when she starts getting loose and no power. Crappy design.
 
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