8 reasons why your car won’t start

Bob Weber
Chicago Tribune

You are running late. To make matters worse, your car won’t start. Why? What can you do?

No-starts fall into two basic categories:

■The engine will not crank or cranks slowly.

■The engine cranks, but does not run.

No or low cranks

Dead battery: A dead battery is the No. 1 cause of a no-start. If the battery is weak, but not totally dead, the starter may turn slowly. You will hear that slow, groaning RRR-RRR-RRR sound. As the voltage drops further, the sound may become a staccato K-K-K. When the battery voltage drops even further, there will be no sound. Even the telltale lights on the instrument panel may dim when you turn the key.

Usually, jump-starting the car will get you on the road, but be sure to find the cause of the dead battery or the situation will recur.

Make sure the clamps can’t easily slip off the battery terminals. Tightening loose clamps may get you on your way.

If the clamps are secure, the battery likely needs a jump. Know the proper way to jump-start a vehicle. Making the wrong connections can cause sparks. Improper polarity may also damage either the donor or recipient vehicle. Learn the proper sequence of connecting and disconnecting the cables as well as where the clamps should be attached.

Some high-end jumper cables (also called booster cables) are designed to prevent inadvertently connecting them incorrectly.

Choose heavy-gauge cables. The lower the gauge number, the heavier the cable. Cheap cables may not be able to carry the electrical current to start the stranded car. The insulation on them may even melt.

Just because you had to jump the battery, it may not be shot. Sometimes it is as simple as charging the battery and cleaning the terminals and cable clamps. Corrosion causes resistance to starting and to proper charging as the car is running.

Bad positive battery cable connections at the power distribution center (usually that fuse block under the hood) or negative connection (usually to a bolt on the engine or body) mimics dirty cables and terminals. The cables should be removed and their connectors cleaned.

If you have doubts about the battery’s condition, have it tested. With today’s hand-held testers, the job only takes a couple of minutes. Many auto parts stores and some repair shops offer free testing. They will not only check the battery condition, they will test the charging and starting systems all at the same time.

Alternator: If it is not up to snuff, the battery may not charge. Although the alternator could be the culprit, don’t overlook a worn or slipping accessory drive belt. If the alternator fails or the belt breaks, a warning light illuminates. If the charging system output is poor, there may be no warning light. If you have a gauge on your instrument panel, it should show about 14 volts.

Even a perfectly functioning alternator may not recharge the battery during short trips, especially if the headlights, wipers, heater, radio, rear window defroster and heated seats are on.

Starter: A bad starter may give the illusion of a weak battery if it draws more current than the battery is able to supply. It will spin slowly and draw excessive power. It will make that GRR ... GRR ... GRR sound, similar to a weak battery.

If you hear a grinding clashing sound like trying to shift with a bad clutch, the starter drive gear or the engine’s flywheel (ring gear) may have damaged teeth.

If the starter does not even turn, its relay or solenoid may be shot or the ignition switch could be the culprit.

Cranks, doesn’t run

If the starter cranks the engine normally, but the engine refuses to run, the battery, starter and alternator are probably fine. The cause lies elsewhere.

Gas: Is the car out of gas? Yeah, it sounds dumb, but it happens. Check that needle.

Fuel pump: Even if the tank is full, a weak or failed fuel pump relay may prevent the fuel from reaching the engine. If you listen closely, you should be able to hear the in-tank pump running for a few seconds when you first turn the key to the “on” position before cranking the starter.

Frozen fuel line: It occurs, but not as frequently where ethanol is blended into the fuel. A can of Iso-Heet in the tank may avoid trouble. To avoid water in the tank, which could turn to ice in the lines, keep your tank at least half-full in very cold weather.

Moist air may condense in the fuel tank as the temperature changes and the resulting water settles to the bottom of the tank.

Spark plugs: Secondary ignition system problems, although rare nowadays, can cause a no-start. It is easy to forget about the spark plugs when their replacement schedule is 100,000 miles.

Security system: Finally, the electronics of the security system can bedevil drivers. Trying to start the car with the wrong ignition key can lead up to a 20-minute delay.

Similarly, remote keyless entry and remote starting devices have been known to create havoc. Proximity keys have a way of going missing, such as leaving them in another jacket or purse, which may turn your morning into something like a scavenger hunt.