Troubleshooting a Onan Generator Marquis

Generator Fails to Crank or Cranks Slowly

• 1

  Ensure that the battery terminals are clean and that the positive and negative battery cables are attached tightly to their terminals. Clean corroded battery terminals with a battery terminal cleaning tool.

• 2

  Use only engine oil of the proper viscosity. If the generator is used in temperatures ranging from 32 to 100 degrees, use a viscosity of SAE-30. If the temperature range is between 10 and 100 degrees, use 15W-40 viscosity. If the temperature range is between 0 and 100 degrees, use a viscosity of either 10W-30 or 10W-40. If the temperature is at or below 50 degrees, use a viscosity of 5W-30.

• 3

  Replace the fuse on the control panel. Raise the maintenance access door on the back of the generator to access the control panel's fuse at the bottom left corner.

Generator Cranks But Will Not Start

• 4

  Ensure that fuel is in the fuel tank, as the fuel level may have fallen below the pickup level.

• 5

  Remove the spark plugs with a spark plug wrench and inspect the tip of each plug for carbon deposits, which appear as a black ash. Replace any fouled plugs.

• 6

  Ensure that the oil supply is full. Note that the dipstick must screw in completely for an accurate reading.

Generator Runs But Stops, or Stops when Vehicle is Driven Around a Corner

• 7

  Ensure that fuel is in the fuel tank.

• 8

  Ensure that the oil supply is full.

• 9

  Drain any excess oil from the generator by removing the drain plug on the bottom of the generator with a wrench.