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Gas Cart Not “Running Right” – Spark Plugs

Type Car: Gas Golf Cars.

Problem: Car not “running right”.

Solution: Look at the spark plug(s). Boy do they have a story to tell.

Tell-Tale Signs From Your Spark Plugs

Spark plugs are of great importance to all small engines, especially those used in idle/start/stop applications like golf cars. Most spark plugs look similar, but they are far from being alike. The common function of a spark plug is to ignite the fuel/air mixture in the combustion chamber. Replacing spark plugs regularly can decrease fuel cost and increase engine performance. Most people only change the plugs once a year and fail to overlook some key tell-tale signs from the plugs which can indicate other internal problems that can lead to engine damage down the road. If you keep a sharp eye out and know how to read the signs, you can save big bucks in expensive engine repairs. Listed below are several plug conditions and their causes. Please refer to the spark plug illustration for proper plug part terminology.

Normal Appearance: A spark plug in a sound engine operating at the proper temperature will have deposits that range from tan to gray in color. The electrode may wear slightly, but there should be no evidence of burning.


Carbon Fouling: Carbon fouling (dry, black, sooty) can be caused by plugs that are too ‘cold’ for the engine, an over-rich fuel mixture, a clogged air cleaner, a faulty choke, or sticking valve. A hotter plug will solve the problem, but only temporarily.


Oil Fouling: Oil fouling (wet, black deposits) is caused by excessive oil in the combustion chamber. Worn rings, valve guides, valve seals, and cylinder walls can cause oil fouling. Again, a hotter plug may relieve the symptoms, but will not correct the problem.


                                                                                                          Ash Fouling: Ash fouling is caused by the buildup of heavy combustion deposits (caked on). They are formed by burning oil and/or fuel additives. This type of fouling can cause a misfire.


Splashed Fouling: Splashed fouling can occur after an overdue tune-up. When a new plug is installed in an engine with excessive piston/cylinder deposits, the plug will restore normal firing impulses and raise the combustion temperature. Accumulated engine deposits may flake off and stick to the hot plug insulator.


Gap Bridging: Gap bridging (deposit bridging the center and ground electrodes) is caused by a sudden burst of high speed operation following excessive idling. It can also be caused by improper fuel additives, obstructed exhaust ports or excessive carbon in the cylinder.


Preignition: Preignition (fuel charge ignited by a glowing combustion chamber deposit or hot valve edge before the plug fires) can cause extensive plug damage. If plug shows evidence of preignition, check the heat range of the plugs, the condition of the plug wires, and the condition of the cooling system (if applicable).

                                                                                     Detonation: Detonation can cause the insulator nose of a spark plug to fracture and chip away. It can be caused by low octane fuel, advanced ignition timing, or an excessively lean fuel mixture.


Overheating: Overheating (dull, white insulator, and eroded electrodes) can occur when a plug is too hot for the engine. Advanced ignition timing, cooling system problems (if applicable), detonation, sticking valves, and excessive high speed operation can also cause overheating plugs.

                                                                                                                                         Worn Out: Extended use will cause the plug’s center to wear away and erode. When the electrode is too flat to be filed, the plug must be replaced. Typical symptoms of worn plugs include excessive fuel consumption and poor engine performance.


Paying careful attention to these guidelines when changing your spark plugs will help you prolong the life of your engine, help you detect serious problems at an early stage, and save big money in engine repairs. A little preventative maintenance will help you enjoy your gas golf car for years to come!