We often get befuddled or confused when looking at engine circuitry and throw up our hands in despair, because it looks to overwhelming.
The first thing to understand about a go kart starting circuit is that the click sound is coming from somewhere. In this instance it is more than likely coming from the start solenoid.
To back up the truck, a starting circuit consists of a switch, a solenoid relay, and a battery. The second circuit is the starter circuit itself which consists of the relay, starter and battery.
The way an engine starts is that you turn the key. When turning the key it guides electricity from the battery to the start solenoid. The start solenoid is an electromagnet that turns on. Inside the electromagnet is a piece of iron that is propelled or pushed away from the electromagnet. This action of pushing is then used to flip a switch.
The flipped switch then connects the high current cables to the starter. The electricity flows through the high amperage cable and into the starter. The starter body itself is made of steel and is grounded to the frame of the go kart. The electricity makes the round trip back through the starter framework and into the negative side of the battery.
There are several possible problems with the circuit:
1. There is a bad ground between the battery and the starter
2. The starter is old, and part of it works. Sometimes a light tap on the starter will dislodge it and cause it to operate. Sometimes the commutators are between windings on the starter and it will get stuck, or not operate. The light tap dislodges the rotor/winding/commutator problem
3. Sticky or Faulty Solenoid: You may hear a click, but there will be no response.
1. The bad ground between the battery can be trouble shot by taking battery cables directly off of the battery and test the starter motor directly. If it spins over, then you have an issue with the electricity coming from the solenoid and getting through the starter. The ground issue may still be the problem.
To trouble shoot further, take the battery cable from the negative side and mount to the frame of the starter. Try starting the engine. If it still does not start then proceed to the next step.
2. With the key in the starting on position, tap the starter motor. If it starts good, if not, then proceed to step 3.
3. A faulty or sticky solenoid may work internally, making the click sound, but may be burnt out, internally. Typically what occurs is that the points in the start solenoid become highly corroded, due to electrical contacts, and so the solenoid may work but not actually function, because the corrosion doesn’t conduct electricity.
To test a faulty solenoid, disconnect the solenoid and use a test light. If the main high current cable points do not cause a closed circuit (short) and turn on the light, then the solenoid is junk. Buy a new one.
The main culprit typically in a start circuit is the solenoid. The secondary problem is a stuck mechanical linkage in the starter itself where it will spin over but not engage the flywheel.
Typically the starter itself will last a long time unless you crank on it for more than a minute. Starters are only designed to run for 10 to 15 seconds at a crack. Any longer and they will overheat and be destroyed internally.
So the next time you come across a starter circuit problem, be sure to follow the 3 step process:
1. Check Solenoid function
2. Check Solenoid to starter connections
3. Check ground and positive wire connections from motor to battery