What To Do When Your Engine Won’t Start
(and it started yesterday)
After a good run, you shut down the engine for the day and settle into a nice anchorage. The following morning, cup of coffee in hand, you press the start button and the engine won’t start. “How can that be,” you wonder. “It ran fine yesterday.”
If I were the unlucky skipper, I’d repeat the process. Assuming no imminent danger, I am better off if it still won’t start, because if it does eventually start, I’m likely facing an intermittent problem, one that will be far more difficult to solve with an engine that does start. The situation can be divided into two basic scenarios: The engine will not crank at all, or it cranks, but will not start.
ENGINE WILL NOT CRANK
Before doing any troubleshooting, check the shift lever position. Many boats have a safety mechanism to prevent starting the engine while in gear. Move the lever in and out of gear a few times and try again. If the engine still doesn’t start, the neutral safety may have failed, and it might be necessary to temporarily bypass this switch to get the engine started.
Assuming that the shift lever was not the problem, start the troubleshooting with the start battery, battery switch, and ignition circuit breaker. First check the voltage of the battery, either at the main panel or with a multimeter at the battery posts. You might be able to eliminate a host of possible causes by checking for voltage at the starter solenoid. The solenoid has two larger terminals (see “Shake Hands With Solenoids,” October 2014). The wire from the battery connects to one terminal, and the other terminal sends current to the starter. While your partner tries to start the engine, test for voltage on the terminal connected to the starter with the positive meter probe on this terminal and the negative probe on the engine block (make sure you have a good connection—preferably find an unpainted bolt or scratch through the paint). The voltage will fall into one of the three following categories.
If the voltage reads “0” the problem is somewhere between the battery and the solenoid, including the ignition switch circuit and the solenoid itself. Check voltage at the battery posts and if you find good voltage there the problem lies between the battery switch and the start solenoid or in the solenoid. Make sure the battery switch and the ignition circuit breaker are in the on position. If yes, then refer to Shake Hands With Solenoids column to troubleshoot and do a workaround.
If the voltage reads between 0 and about 8 volts, the problem is either the battery or the starter itself. Check voltage at the start battery (while cranking). If it’s between 0 and 8 volts, you have a battery problem. Start the engine from an alternate battery, or start the generator and make sure the charger is working. Some boats have a parallel switch for engine starting. If you have the option to select an alternate battery, that is a better approach than using the parallel switch. Here’s why: If the start battery has a bad cell, when you parallel with a good battery you weaken the healthy battery. Parallel switches work well when you have a healthy battery that is low, but not when the battery has a severe problem. Boaters often underestimate the condition of a battery based on the voltage. Keep in mind that at 12 volts a battery has about 50 percent of its capacity remaining, and at 11.5 volts only about 10 percent remains.
If the battery has good voltage (12 volts or more) the problem likely will be at the starter. Examine all wiring connections, especially at the starter. If you find rust or corrosion, turn off the battery switch and remove and clean the terminals. If the terminals look good, try tapping the starter with a phenolic hammer or the wooden end of a metal hammer while cranking.
This practice should only be attempted on older Bendix type starters. On the newer planetary gear starter motors tap-
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