©eBlue-Dist 2007
CHAPTER THREE
Because resistance generally increases with temperature, perfosm resistance tests with the circuit or component cold (room temperature). Aresistance test performed on a hot component will indicate increased resistance and may result in unnecessary parts replacement without solving the basic problem. CAUTION Do not connect an ohnzmeter to a live circuit or comporzent. Always isolate the circuit or component from voltage prior to attaching an ohmmeter or tlze meter will be damaged.
Amperage Current is the flow of electricity in a circuit and is measured in amperes (amps). Amps are measured using an ammeter attached in a simple series connection. To connect an ammeter, the circuit usually must be disconnected and ammeter spliced into the circuit. Always connect the positive ammeter lead to the source (where electricity is coming from) and the negative lead to the load (where electricity is going).
COMPRESSION
Checking Diodes An ohmmeter is often used to check diodes within various engine components. Some meters have a diode test option. Diodes function like electrical check valves. First check for continuity by measuring between two leads or terminals. Then reverse the meter test leads and check for continuity again. No continuity when connected one way and continuity when the leads are reversed generally indicates a good diode. Do not be concerned about test lead polarity, as variations exist from one meter to the next. TROUBLESHOOTING PREPARATION Before troubleshooting, verify the model name, model number, horsepower and serial number of the engine. It is essential that the model be identified correctly before servicing the engine. In many cases, the tables list specifications by horsepower and/or model name. For most models, identification tags may be found on the clamp bracket.The information provided on the tag is required when purchasing replacement parts for the outboard. Most engine problems may be resolved by completing a basic inspection. Check the following tips and refer to Tables 1-5 at the end of this chapter for starting, fuel and ignition troubleshooting. Additional troubleshooting tips are provided in this chapter for the specific system or component.
1. Inspect the engine for loose, corroded, broken, cracked, or disconnected wires. 2. Make sure the engine has fresh fuel. 3. Ensure the battery is fully charged and cable connections are tight and corrosion-free. 4. Check for ignition spark at each cylinder. 5. Check the spark plug condition and make sure the spark gap setting is correct. 6. Check the location of the lanyard switch; make sure it is in the run position. 7. Verify that the boat hull is free of any obstructions.
