Operation Section 61 Problem Probable Cause Corrective Action Rough Idle Incorrect Idle speed control See Advanced Diagnostics & See Engine Service Manual Incorrect timing or spark control Engine Mechanical See Engine Service Manual High Idle Speed Incorrect Idle speed control See Advanced Diagnostics & See Engine Service Manual Throttle sticking Foot pedal sticking or incorrect pedal signal Check pedal return spring travel for binding z See Advanced Diagnostics Poor High Speed Performance Clogged fuel filter Repair/replace as required z See Maintenance section, Fuel Filter replacement Plugged fuel line Remove obstruction from the fuel line z Close liquid fuel valve z Using caution, disconnect the fuel line (some propane may escape) z Clear obstruction with compressed air z Re-connect fuel line z Slowly open liquid fuel valve & Leak test Air filter clogged Check air filter z Clean/replace as required Faulty vapor connection between the pressure regulator/converter and the mixer Check connection z Verify no holes in hose z Clamps must be tight z Look for kinked, pinched and/or collapsed hose Pressure regulator malfunction Test pressure regulator operation z See Engine Service Manual Air/Fuel Mixer malfunction Check mixer z See Engine Service Manual Restricted exhaust system Check exhaust system z Measure exhaust back pressure Incorrect ignition control See Advanced Diagnostics & See Engine Service Manual Incorrect air/fuel control Incorrect throttle position