Help! My Outboard Won’t Start!

Step-by-step troubleshooting to help you pinpoint problems.

Murphy’s Law says your boat won’t start when you have a cabin (and boat) full of guests. While outboards have become more and more complex, they still operate on the same principles as they did before the current wave of EFI/DFI and four-stroke technology appeared. To start and run, an outboard needs:

1. Ignition (properly timed)
2. Fuel/Air mixture (in the right ratio)
3. Compression
4. Exhaust

This guide will help you isolate the problem so that you may be able to solve it at the dock; if you can’t, you’ll be able to speak intelligently about the problem to your mechanic. [gallery link="file" columns="4" ids="64458,64460,64451,64450"]

Engine Won't Crank/Cranks Slowly

Main Fuse: If you try to crank the engine and nothing happens, check the power trim as well as see if the gauges come “on.” If everything else is dead too, check the outboard’s main fuse. Typically located in a large red holder on the engine wiring harness, it’s usually a 20-amp fuse. If the fuse is OK, check the main power plug that connects the engine to the boat. Battery Switch: If your boat has a battery switch, ensure that it’s switched to “on” or “both” and try the key switch again. Neutral Safety Switch: If you turn the key and nothing happens, but other components (see Main Fuse above) are working, check the gear shift to ensure it’s in neutral. Battery: If you turn the key to crank the engine and nothing happens, or the starter engages and cranks slowly, your battery may be dead or low. With a voltmeter, check between the positive and negative terminals; a minimum of 12 volts is needed to adequately crank the engine. If the battery is undercharged, and you have a jumper box or spare battery, try jumping it (carefully connecting the positive and negative cables in an open bilge). Battery cables and connections: If your battery’s reasonably charged, check the battery cables from the battery to the engine. They may be loose or corroded, as cables themselves can become so corroded over time that they won’t carry enough current to start the engine. Tightening and cleaning them restores the connection. Starter Solenoid: If you hear a clicking sound or a low whine but the starter won’t engage the flywheel when you turn the key, the starter solenoid may be the culprit. Tap lightly on it with a small hammer as a helper turns the key. That’s sometimes enough to get it to engage and send current to the starter. Replace the solenoid whether or not this process works, as it indicates that the solenoid is corroded and/or failing. [gallery link="file" columns="4" ids="64452,64449,64454,64447"]

Engine Cranks But Won't Start

Kill Switch: A simple thing to overlook; ensure that the emergency shutoff switch cap is in place. If it is, and the engine won’t fire, proceed to “Spark Check,” below. Spark Check: Your outboard needs spark at the spark plugs in order to start. Remove one spark plug wire and spark plug. Reconnect the wire to the plug and lay the plug against the engine block so that the metal of the plug is firmly touching the engine block (to ensure that it’s grounded). Have a helper crank the engine while you check the electrode (firing end) of the plug for spark. Be careful! Don’t hold the plug with your bare hand or with a bare metal tool. The spark will shock you, though not enough to hurt you — but it may cause you to recoil enough to hurt yourself. Check each plug and wire individually. If you see a strong blue spark, the ignition system can fire the engine. If no spark on all cylinders, the culprit is typically the key switch, kill switch or ignition power pack. At this point, call your dealer. Fuel Check: Check to see that fuel is actually getting to the engine. Pump the primer bulb until it fills with fuel and gets firm. If it doesn’t, check for leaks. If the engine has an electric primer, remove one of the small fuel hoses from it that goes to the engine’s intake or carburetor. Have a helper operate the primer (usually pushing the key in), while you watch to see if fuel squirts out from where you removed the hose . Newer EFI/DFI engines don’t have primers. A squirt of fuel directly into the air intake can help; if the engine fires on that small shot of fuel but won’t start without it, the fuel system’s the problem. Compression. If you’ve ruled out electrical, spark/ignition and fuel problems, but the engine still won’t start, it may have an internal problem, such as low compression. A compression gauge is inexpensive and available at auto parts stores. Most engines will show cranking compression of at least 85 to well over 100 psi. If your compression is below that or one or more cylinders is more than 15% lower than the others, bring your boat to a mechanic. [gallery link="file" columns="4" ids="64459,64461,64462,64457"] Exhaust. As a last resort, check the exhaust outlets for blockage. We’ve seen rodent nests built over the winter cause exhaust blockage significant enough to keep the engine from starting. This guide is to help you pinpoint problems at the dock or launch ramp, with minimal tools and in a short amount of time. It’s by no means a complete troubleshooting guide for engine starting problems. This article is by John Tiger, who has spent his lifetime and career around boats.