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Kevin, Technician
Category: Small Engine
Satisfied Customers: 729
Experience:  Over 10 years as a Deere Service Tech.
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I am getting gas in my oil on riding lawn mower, what would

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I am getting gas in my oil on riding lawn mower, what would be the cause and how do I fix it?


Hello Dave, my name is XXXXX XXXXX I can help you with this problem.


There are two common causes for gas leaking into the engine oil. The most common cause is a faulty carburetor float or needle valve allowing gas to leak into the intake and then into the crankcase. To check for this problem follow these steps.

  1. Shut off the gas to the carburetor, if your mower doesn't have a shut off valve simple pinch the fuel line with a pair of vice grips.
  2. Using a wrench remove the carburetor bowl retainer, this may look like a bolt head or a nut with an adjustable valve through it.
  3. Carefully remove the bowl by using slow gentle side to side motions so as to prevent the sealing o-ring from being damage.
  4. Once the bowl is removed you will see the float hanging by a retaining pin, hold the float and remove the retaining pin.
  5. Take a good look at the needle valve that is attached to the float, it should have no grooving or damage to the tapered end. If there is visible signs of wear then the needle valve and seat should be replaced.

The second most common cause is from faulty mechanical fuel pumps. Your engine may or may not have this option. If you have no fuel pump mounted on the side of your engine then you do not have this setup. In the event you do have a fuel pump, and you did not find the problem in the carburetor follow these steps.

  1. Shut off fuel as described before.
  2. Remove both inlet and outlet fuel lines.
  3. Remove the two retaining nuts and remove the pump from the engine.
  4. Hook the fuel lines back up to the removed fuel pump and turn the gas back on.
  5. Manually move the pumping lever and inspect for gas leaking from the pump.

Please let me know if this doesn't help.



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