offers the highest quality tools to get the job done right. Spark plug misfires occur when the sparks jumping the gap of electrodes are inconsistent in timing, causing the engine to stumble or lose . This handy little helps you watch the gap in the spark plug tester to see whether or not you have inconsistent timing! HEAVY-DUTY CONSTRUCTION: Made only with the best materials to allow you to test if your spark plug is working properly. Saves time & money by checking if the problem is actually in your ignition! Engineered with only the strongest highest-quality materials, the Spark Plug Tester works to troubleshoot spark plug connections, diagnose spark misfire or spark miss, defective contact points, bad cables and more! Specialty tools like the Inline Ignition Spark Tester were made to keep your vehicle running in condition. Works very well with lawnmowers, motorcycles, small engine vehicles and many more! How to Use the Inline Ignition Spark Tester: Remove the spark plug from the spark plug hole. Take the Inline Ignition Spark Tester's indicator end and connect it to the spark plug wire boot. Connect the other end to the spark plug through the spark plug hole. Test the spark by starting your engine. Watch the see through window in the Inline Ignition Spark Tester for timing irregularity. Sparks that jump the electrodes are inconsistent and indicate that you need to replace the plug. If you are testing a no-start condition, have a friend crank the engine. Stop losing to your engine! The Inline Ignition Spark Tester analyzes engine stumble, loss and excessive smoke emission. Just follow the 3 simple steps above to check if your spark plugs are missing or misfiring. Features: Checks for spark ignition, no-start conditions and spark strength at each cylinder Flexible connector hose for secure spark plug connection Delivers accurate diagnosis in just seconds Transparent hose connector for easy-to-see diagnosis colour: black Material: plastic+metal Package Contents: 1 x Foolproof engines For the Spark Tester NOTE: Dirty, clogged spark plug holes can cause a loss of spark. If engine loss is a problem for you - a Double-Ended Thread today, too! Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.