What to do When Your Motorcycle Won't Start

Fueling Around

Loosen the float-bowl drain screw and allow some of the fuel to run out. If possible, catch it in a small container. If there is water in the fuel, it will appear as globules. If water or lots of dirt is evident, drain the float bowls completely and allow them to refill before trying to start the bike. \ If the float bowls are dry, or there is little fuel in them, the problem most likely lies in the fuel delivery system. If the bike has a vacuum-operated petcock, turn it to prime. If fuel starts to flow, the problem lies in either the petcock or the vacuum line; a little detective work should pinpoint which. If the petcock is manual, move the lever to reserve. If fuel flows, you're either low on fuel after all, or the petcock main feed is plugged or damaged. If no fuel flows, remove the fuel line at the petcock and try everything again. If fuel flows from the petcock but doesn't reach the float bowl, the problem is most likely a plugged fuel filter or line.

Some motorcycles, primarily those using remote fuel tanks or fuel injection, use an electric fuel pump. Testing procedures for these vary, so you'll need to refer to the shop manual for the correct method. But as a rule of thumb, you can test the pump by one of two methods. Start by disconnecting the fuel line from the carburetor or injector. Place the open end of the line in a container and turn the key on. Fuel should gush out of the line. Some pumps are only activated when the engine is cranking or running. If the first test didn't produce any results, try cranking the bike for a few seconds to see if things change. If neither method produces any results, chances are that the fuel filter is plugged, or the pump or the circuit controlling it have failed. If you suspect the pump itself, check the electrical connections and the fuse that feeds it before condemning it.

Injection Issues

Bear in mind that troubleshooting a fuel injection system requires some very expensive and specialized equipment. My recommendation here is to tread very lightly--this is really trained-technician territory. No less a consideration is safety. FI systems work at extremely high pressures; get in front of a working injector nozzle and you're going to be in a world of hurt.

Injectors rarely fail. It's usually the pump that's the troublemaker. Most FI pumps run for a few seconds whenever the key is turned on to pressurize the system. Get in the habit of listening to yours when the bike is healthy so you know what it should sound like. If she won't start, take a good listen. Can your hear the pump run? If not, check the pump fuse. As a last resort, try cranking the engine while you spray a very brief burst of carb cleaner into the air intake. If it catches and runs, you know there is some fault in the fuel injection system. Determining where it lies will most likely call for a trip to your favorite shop.

Hey Sparky!

To check the spark, remove one plug from the engine. If it's wet with unburned fuel, it's a safe bet that the plug is either fouled from too much choke (yes, I know they're not "chokes"!), or you've lost the spark. If the plug is fouled, give it a thorough cleaning, insert it back into the cap and lay the plug on the cylinder head or engine case. Make sure there is no spilled fuel in the vicinity. Crank the engine over while observing the plug. There should be a nice fat blue spark crackling from the tip. If there isn't, try a new spark plug, a known good one, before condemning the ignition system.

If no spark is forthcoming, you'll have to decide how involved you really want to get in the troubleshooting process. The problem could be as simple as an unplugged or dirty connection, or it could lie in the ignition module or signal generator. If you have the tools, skills and inclination to track down the problem, go for it, but for the rest of you, this is another instance where I'd recommend you call the dealer and make a service appointment. Be forewarned that electrical problems on modern bikes can crop up suddenly, and can take some head-scratching to find.

Uh-oh

If you've got good spark and fuel and she still won't start, you'll need to do either a compression or leak-down test to discern where the problem might lie. In the real world, sudden, overnight losses of compression are rare. However, if the bike has been sitting for any length of time, then all bets are off. If you don't have the proper test equipment, a quick and dirty test is to hold your thumb or finger over the spark-plug hole and crank the engine. If you can feel noticeable pressure, the compression is probably enough to get the engine started. If not, it's time to do a proper check before going any further.

Modern motorcycles are notoriously reliable, but things do go wrong. In my experience, many no-start conditions turn out to be something relatively minor--usually no fuel or a bad connection somewhere that kills the ignition. Remember, engines need spark, compression and fuel to run. To get back on the road, all you have to do is figure out which one is missing.

For more articles on how to maintain and modify your motorcycle, see the Tech section of MotorcycleCruiser.com.