What to Do When Your Motorcycle Won't Start

Start with the easy stuff. Is the fuel turned on?

At this stage, you have two options. Option number one is to forget the whole thing, go back in the house and sulk in front of the TV until you can get the bike to the shop. Option number two is to try and salvage the day. True, your bike's ills may be too serious for home remedies. But there's at least a 50/50 shot that whatever's ailing old paint is relatively minor and easily rectified, which (a) will allow you to get back on the road, and (b) save you some dough. All in favor of option two, raise your hands.

Basically Speaking

When the float-bowl drain is opened, does clean fuel run out?

Internal combustion engines need three things. They must have good-quality fuel, compression and a spark delivered to the compressed fuel/air mix at the appropriate time, or very close to it. Given those three items, an engine will run. Since the majority of you probably own bikes that start with a button, the fourth item you'll need is enough electrical energy to spin the starter.

Before You Get in Trouble

Basic troubleshooting requires little in the way of tools and skills. However, you should at least feel comfortable removing a spark plug, draining a carburetor and using a voltmeter or test light. The tools needed to perform these basic chores can be purchased for less than 50 bucks. I'd also recommend that you buy a factory service manual or its equivalent if you plan on keeping your bike past the warranty expiration date.

Nothing Happens

With the discharge line disconnected and the key on, the pump should push fuel.

D'oh. I hate it when that happens! At the risk of seeming condescending, you did follow the correct starting procedure, didn't you? Every motorcycle has its own starting drill. Many require that the clutch be held in, whether the bike is in gear or not, and some want the bike to be in neutral anytime it's on the kickstand. Before you panic, verify the starting procedure, especially if it's a new bike that you're not entirely familiar with. It may sound obvious, but make certain that someone hasn't moved the kill switch to off, especially if you have little urchins running around who love to sit on motorcycles when mom and dad aren't watching.

If everything is in order and she won't even spin, the most likely culprit is a bum battery or something that's preventing the battery from doing its job. Most of us are familiar enough with the conspicuous signs of a dead battery: dim lights, a weak horn and slow or no starter activity. Push the horn putton, if the horn sounds anemic, the battery is probably the culprit.

If that seems to be the situation, it's time to charge or possibly replace the battery. Before you do, though, check the battery terminal connections. It's possible that the terminals are loose or corroded, and a good cleaning and tightening are all they need. Follow that up with a voltmeter reading across the battery terminals, or a hydrometer reading of the cells. If the voltmeter reads less than 12.5 volts (no load) or 11.5 volts with the lights on, or the hydrometer reads less than 1.265 (less than four balls floating), it's time to service and recharge the battery.

To check fuel flow when a remote tank/pump is used, locate the fuel pump. This one is located under the side cover. Remove the discharge side hose--that's the one from the pump to the carburetor.

Charging the battery is going to take some time. You may be tempted to try and jump-start your bike from your car or a buddy's bike. It can be done, and in the past I've certainly done it. However, many late-model motorcycles, particularly those that are fuel injected, utilize some sort of microprocessor. Computers are highly sensitive to voltage spikes, and nothing causes a spike like a jump-start. If you're unsure about the jump-starting procedure for your bike, play it safe and sit this dance out, at least until you can verify that jump-starting your bike is safe.

Obviously, the worst-case scenario is going to be a good battery and no action at the starter motor. If that turns out to be the case, you'll need to do some troubleshooting. Start with the simple things. Likely trouble spots include a blown fuse, or a malfunctioning kickstand safety switch or clutch/starter interlock switch. If the culprit is a blown fuse, replace it with one that carries the same amperage rating and give her another try. If the fuse blows again, you've got a dead short somewhere, which will need to be repaired before you go much further. If one of the switches is suspect, they can be bypassed with a jumper wire to get you back on the road.

Spins But Won't Catch?

If the bike turns over normally without laboring, chances are pretty good that the problem lies in either the fuel or ignition system, particularly if the bike was running fine when it was put away. As above, start with the easy stuff.

No fuel flow? Suspect the filter.

Did you do anything to the bike before putting it away that may have created a problem? For example, if you pressure washed the bike, water may have entered the ignition switch, plug caps, kill switch or kickstand safety switch. A spritz of WD-40 or some other moisture-displacing lubricant may solve the problem.

Is there fuel in the tank? Sure, you know there's plenty in there, but play it safe, pop the cap and take a look. If you can't see it sloshing around, the tank might be empty after all. Of course, on bikes with underseat tanks and remote filler caps, this check won't be possible. If the bike has a petcock, an item that seems to be found less and less these days, place it in the reserve or prime position and try starting the bike. Still won't start? The two most likely suspects: Either fuel isn't reaching the engine (assuming that the tank is full), or you've lost the spark. If the bike shows absolutely no inclination to start, I'd head for the spark plugs. If the bike coughs and sputters, I'd lean toward the fuel delivery side. But don't forget, fouled spark plugs will certainly make a bike hard or impossible to start, and may mimic a fuel delivery problem. Actually, since I'm pretty lazy, I always check the easiest thing to reach first.

Fueling Around

Unlike this one, there should be a big blue spark at the plug when you crank the engine.

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.

Clutch safety switches sometimes go bad, as does the odd kickstand safety switch.

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.

Both kinds of switches can be bypassed with a short piece of wire.

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.