What to do if your car doesn't start

A driver's worst nightmare is that time when his car won't start. Or, the engine dies exactly when he is negotiating a tricky crossing. It's even more worrisome if the driver is a lady (especially in India) and the sun has already set, or if the location is a lonely highway instead of the city. This is the time when one regrets not knowing a little more about how cars work.

Good news is, diagnosing why your car won't start isn't exactly rocket science. This guide, a little bit of common sense and a cool head might just be enough to get you back home.

Step 1: Understanding the Basics
Before you begin the process of troubleshooting, it is absolutely essential that you ensure your own as well as others' safety by pushing the dead car safely to the side of the road.

There are essentially 3 systems that start your engine up:

1. The Electricals: Powered initially by the battery, the electrical system runs your starter motor which turns over the engine and allows it to fire up. It also provides the spark to the spark plugs in a petrol engine (to ignite the fuel-air mixture). In modern engines, the electricals need to supply power to the electronic control module (ECM) as well. Once the engine is running, the alternator recharges the battery and also keeps the other electrical systems running.
2. The Fuel: Usually petrol or diesel, but alternate fuels like CNG and LPG are also used by a small percentage of owners. Since the car has stopped and it is an emergency, CNG / LPG-fueled cars should switch over to petrol. Thus, our troubleshooting sequence remains the same.
3. The Engine: The fuel, air and (in petrols) a high voltage electric charge come together to generate the motive force in a mechanical manner by the engine. Things rarely go wrong here, but if they do, you should be able to identify what happened.

In the next few posts, we shall progressively try to identify what is preventing your engine from running, and explain some quick repair methods. The ultimate solution for the mechanically-challenged individual is to call the manufacturer's helpline and / or have the car towed to a workshop. But before you do that (it can take an hour or more for roadside assistance to turn up), let's try to get you home safe.

 

Step 2: Checking the Electrical System

About Push Starts:

A push start may or may not work with the problems listed below. Do note that a push start won't get you anywhere if your battery is completely flat and the fuel delivery system gets no power. As an example, check this thread out. Also, not all cars can be push started; check your owner's manual for details.

The commonest culprit at the root of preventing your engine from starting up, or that caused it to die suddenly, is the electrical system. Turn on the ignition switch, but don't crank the starter. Are all the telltale lights on the dashboard coming on & fully illuminated?

If YES (all dashboard lights are on):

Determine if the battery has enough charge to be able to start the car. A quick way to check is to turn on the headlights and blow the horn. If the lights dim and the horn sounds hoarse, you have a nearly flat battery. It's push-starting or jump start cables to the rescue!

If there are absolutely NO telltale lights on the dashboard:

• A completely drained battery (did you leave your lights on last night?). Time to bring out those jump start cables and hook up to an obliging neighbour or friend's car.  A neat video:

• A loose connection at the battery terminal (check if the terminals are tight, or if there is excessive corrosion).

A blown main fuse. Check your owner's manual to locate the main fuse. Replace the fuse (if you have a spare) and try again.

Be prepared that the fuse might blow again, in which case there is a short circuit somewhere and you need to summon professional help.

If the starter motor is turning over, but is slower than normal:

• Your battery has low charge. You may start the car with a push-start or call for assistance from those jump start cables. No point in persistently trying to crank in the hope that the engine will fire because it usually doesn't, and the battery will run down completely.

If there is no noise from the starter at all:

• Some cars won't crank unless you depress the clutch pedal fully, or shift the transmission to 'neutral' or 'park' position. Silly mistakes happen to the best of us.
• If you do not hear a clicking sound from the starter solenoid (relay) when you attempt to crank the engine, you may have a defective starter solenoid, and the starter motor isn't getting any current at all.
• The starter motor cable may have come loose (no contact). Tighten and re-try to start the car.
• Your ignition switch is burnt out (older cars) or faulty.

If you hear an audible "click", but the motor doesn't turn over:

• The starter motor solenoid (relay) is actuating, but the Bendix gear is perhaps jammed up against the ring gear. Place the car in 3rd / 4th gear and push / rock the car backwards to release the Bendix from the ring gear. You'll hear an audible click as the car moves backwards a little, in case the Bendix has actually jammed against the ring gear (usually caused by broken/worn teeth in the Bendix or ring gear). Try starting the car again. Warning: DO NOT hold the key in "start" position for too long if you hear the click and the starter motor won't turn. It'll burn out the starter armature windings.
• A loose connection on the starter motor cable - not enough current getting through for the starter to turn.
• Starter motor brushes worn out.
• Check and tighten the contacts, and tap the starter motor body with a heavy stick or rod. Watch the following video, especially from the 1:28 point onward.

 

If the starter motor churns over normally, but the engine will not fire:

• A push-start won't help in this situation.
• Your central locking / security system may be intervening by cutting out power to the ECM. Reset the central locking system and try again.
• Some cars have a fuel cut-off inertia switch. If someone had rammed your parked car, it could have triggered the inertia switch to cut off the fuel supply. Check your owner's manual for details on resetting the inertia switch.
• For petrol engines : No spark at the plugs. The HT coil may have failed. For older distributor-type engines, there could be moisture in the distributor cap, or a fouled set of contact breaker points. For newer engines, OBD may be needed (i.e. hooking up a laptop to the car) to detect what is causing this. The spark plugs usually require special tools to remove and check, which may not be possible for the average motorist. Call for professional help.
• For diesel engines : Air in the fuel line. More about fuel systems later.
• For both, petrol and diesel engines : The engine isn't getting enough fuel.

The engine starts, but refuses to rev up or dies out after a few seconds:

• Check if there is fuel in the tank? Is there coolant in the radiator and is the engine temperature normal? Fuel flowing from tank to pipe into the engine?
• Electricals: Open up the fuse box. Take out the relevant relays / fuses for fuel injection and other vitals. Ensure that they aren't blown, clean contacts and reinstall.
• The fuel feed is erratic (such as with a choked fuel filter; more info in the next posts).

WARNING: Do not continue to run down the battery by repeatedly cranking the starter motor, if the engine turns over well but will not start. You don't want a dead battery over and above other issues.

tep 3. Part A: The PETROL Fuel System

Once you've made sure there are no gremlins in your electrical system, it's time to check whether the engine is receiving fuel.

• An empty tank does not run a car. However, the only way we think we can find out whether there is fuel in the tank is to depend on the fuel gauge. What if the fuel gauge has malfunctioned and is stuck at half-full? A quick solution is to open the filler cap and place your ear close to it. Ask someone to shake the car from side to side. The resultant sloshing sound inside gives a fairly good idea of whether there is sufficient fuel there. Applies to both, diesels and petrols. If you've been caught unawares with an empty tank, well, it's time to deploy / borrow a jerrycan.
• Once you have filled up, turn on the ignition and wait for a minute or two to allow the electric fuel pump to prime the fuel injection system / carburettor, before trying to crank the engine.
• If you do have fuel in the tank already, disconnect the fuel feed pipe in the engine and hold its tip inside the mouth of the jerrycan. Then, ask someone to turn on the ignition. This will cause the electric fuel pump to run and you should be able to see a steady stream of petrol filling the can up (at least 1 liter per minute).
• If you have no fuel coming out, the fuel pump inside the tank isn't working. It could be a blown fuse or relay (simple to replace a fuse, or tap the relay a few times and see if it comes back to life). On the other hand, if the fuel pump has failed, you need to tow the car to a service station and get a replacement.
• If fuel flow is erratic (intermittent or very slow flow), one of the fuel filters (either the coarse filter inside the tank or the fine filter inside the engine bay) is choked. Try shaking the rear end of the car from side to side to dislodge some of the muck from the in-tank filter, then take out the engine-side filter and tap out the dirt in it (fill with petrol, shake well, then tap gently on a hard surface with the "IN" side facing down).
• Also check the fuse / relay for the FI pump (for modern fuel-injected engines).
• For a carburetted engine, make sure that the engine isn't flooded with petrol, and that the choke isn't applied.

Step 3. Part B: The DIESEL Fuel System

It's more trouble to end up with an empty tank in a diesel car compared to a petrol car, because a diesel fuel system absolutely abhors air in the lines. Running on empty automatically means air has been sucked into the fuel lines, and one needs to bleed off air and prime the system.

Each type and model of diesel engine will be slightly different in how the bleeding is done. Almost all diesels (DI, IDI, CRDi) have a manual bleeding mechanism of some sort at the fuel filter. It's usually a lever (like some Jeeps), bulb (like the Safari) or a push-button (like the Scorpio) that is pumped repeatedly to push out air from the system.

If you are sure about there being enough fuel in the tank, you need to check whether a fuse for the in-tank (low pressure) pump has blown, whether the low pressure pump has gone kaput or if the filter inside the tank is clogged. The procedure is similar to what has been described for petrol engines in the post above.

Diesels also have this nasty habit of refusing to run when there's any water in the fuel. Unfortunately, petrol pumps have a nasty habit of selling you water-laden diesel in the monsoons (not completely their fault, but we need to blame someone, don't we?). Once that happens, the sedimenter bowl below the diesel filter fills up with water, a warning light shows up on the dashboard and the engine refuses to start / runs erratically / cuts out suddenly.

Here's how to drain water from the fuel filter of an Innova. The basics remain the same, but each car has its own required technique.

In rare instances, even with a tankful of diesel, the fuel system will draw in air and cut off the engine as a result. This can happen because of a leaking (damaged) fuel line, or (for avid off-roaders) if your car has tilted so sharply that the suction end of the electric fuel pump is not completely immersed in the diesel inside your tank. After the root cause is addressed (sealing a fuel line leak or getting the car back straight and leveled), the method of bleeding and priming the system remains the same as described above.

The adventurers among us have, on many occasions, found their diesel engines refusing to start at high altitudes in cold climates. Read these threads:
In most cases, if you've been caught unawares and cannot start your car at 14,000 ft and (-)5 degrees C, it's best to wait it out until the sun comes up and the weather is warmer.

Step 4: Knowing when to say "I Give Up!"

Apart from the electricals and fuel feed system, there are a thousand other things that could go wrong and prevent your engine from firing up. If the culprit is the engine itself, there isn't much that one can do on the roadside, and towing the car to a garage is the only way out. From a blown head gasket to a broken crankshaft, from fouled injectors to ECM failures, from seized pistons to snapped timing belts, anything can make an engine dead and leave you stranded. Of course, it's another matter that the engines of today are far more reliable and robust than those manufactured even 20 years ago, but catastrophic failures are still not unheard of. Some of the reasons may be poor compliance with maintenance schedules and / or use of sub-standard spare parts. Here's a word of warning:

If you hear strange / unusual noises coming from your engine when trying to restart it, or if your engine stopped running after making weird noises, do NOT attempt to restart. The same applies if you find smoke pouring out of the engine bay or tailpipe, or if the engine overheated and stopped.

Some other notable vehicle-specific threads about failure to start:

• Tata Indica.
• Hyundai Verna.
• Honda Civic.
• Skoda Octavia.
• Tata Manza.
• Ford Fiesta.

Jump Start Cables:

Having a pair of jump start cables around might help you, a neighbour or a friend. The cost is marginal and it's a good idea to park a set in your car or garage (Image Source : Ebay.com). A basic tool kit & spare fuses are other essentials, while a jerrycan and tow straps can come handy.




This Article have been sourced from various Team-BHP threads. Thanks to BHPians for shooting & sharing them.