Engine Cranks – But Fails To Start – What Should You Check




Engine Cranks - But Fails To Start - What Should You Check
Engine Cranks - But Fails To Start - What Should You Check

What should you do when your engine cranks, but fails to start.

If your engine cranks normally, but fails to start; at least you know your battery is good and the starter motor works.

So, before your car would not start, did you notice anything out of the ordinary; such as low power or a check engine light?

This could aid in the troubleshooting and diagnosis process of an; engine cranks but fails to start situation. If you are going to be repairing the enginge yourself then be sure to take note of the auto labels that the manufacturers are required to put on the parts as they will have warnings and occassionally instructions on them that will keep you safe.

Above all, to operate efficiently, an internal combustion gasoline engine needs:

  • A good spark.
  • The right amount of fuel.
  • Good compression (a healthy mechanical condition).

So, the lack of any of these three things will prevent your engine from starting.

Visual Inspection Of The Engine
Visual Inspection Of The Engine

So, always start with a visual inspection of the engine. Is a wire loose? Did a vacuum line fall off ? Do not look for a complicated solution to a simple problem. Consequently, it is common to have a problem in one area, that impacts three or four others.

So, you have eliminated the battery and starter, let’s move on to spark, fuel and compression.

SPARK / FUEL / COMPRESSION

Consequently, if any of the three are missing your engine will not start.

Let’s Start With Spark

Conventional Ignition

Checking For Spark
Checking For Spark

(NOTE: If you have plug wires). To do a quick test for spark; remove one spark plug or use an extra spark plug in your tool kit. Attach the spark plug to the spark plug wire. Now, use a jumper cable and attach one end to the spark plug; and the other to the negative post of the battery. Finally, try turning over the starter and see if the spark plug is firing. So, if the plug does not fire there could be other problems.

Other possible causes include:

Distributorless Or (COP) Ignition

However, you can’t check for spark the way described above on most newer cars. Because, they have what’s known generically as a (DIS) or “distributorless ignition system”. Spark timing is controlled by the computer in this case. There will either be a coil pack or two (or more), depending on the number of cylinders.

If your car has either of these, you can check for spark by following these steps:

  1. Remove a plug wire or coil from the spark plug.
  2. Connect a spark tester to the plug wire or coil.
  3. Clip the plug tester to a good ground.
  4. Have someone crank the engine over as you look for spark.
  5. Repeat for each cylinder.
  6. For any cylinder/plug wire/coil that does not generate a solid spark; use a multimeter or test light to check for the presence of power to the coil when cranking the engine.
  7. If no power is detected, locate the cam/crank sensor(s) and test them for power; and for opening and closing as the engine cranks.

Moving On To Fuel

Checking For Fuel
Checking For Fuel

To do a quick test for no fuel get a can of starting fluid or propane. Spray some into the air intake system through a hole where there is a fitting or; hose opening to the throttle body/carb/etc. Try to start the engine, if it starts and then turns off; you are not getting fuel from your gas tank to the engine.

Other possible causes include:

  • Bad Fuel Pump ( Tip: Turn of key and listen for buzzing Noise From Fuel Tank )
  • Blown Fuse
  • Fuel Pump Relay
  • Low or No Fuel Pressure
  • Fuel Injectors or Relay
  • Bad PCM

Finally, Check For Compression

Checking For Compression
Checking For Compression

To do a quick test for no compression do a compression test. If you are doing a compression test you need to have at least; 125 lbs of compression for your engine to run. If you have good compression in all but one cylinder; it will still run but miss on one cylinder.

Other possible causes include:

  • Broken or Slipped Timing Belt or Chain
  • Burnt or Bent Valves
  • Worn or Damaged Pistons or Rings
  • Broken Camshaft or Crankshaft

Also, faults in other systems, not just ignition, fuel, or compression problems; can prevent your engine from starting. Consequently, a system component itself may be faulty; or there may be a problem with its wire connector or harness.

Engine Cranks - But Fails To Start, Check System Components
System Components

Any one or combination of the following issues may be the source of the problem:

  • Plugged Exhaust System
  • Check Engine Trouble Codes
  • Test Fuses
  • Check the Security System
  • Worn out tune-up parts
  • Fuel injection problems
  • Vacuum leaks
  • Contaminated fuel
  • Weak fuel pump or fuel pump relay
  • Bad contacts in the ignition switch, key code problems
  • Ignition coil or module

Intermittent Engine Cranks – No Start Problems

Sometimes a car may have an intermittent problem. When it starts fine most of the time; but once in a while the engine cranks, but fails to start.

What will help to find a problem of this type is if you notice when; under what conditions and what helps to get it started.

For example, if you notice that wiggling the ignition key helps to get the car started; it may tell you that the problem is likely with the ignition switch, which is very common.

Engine Cranks - But Fails To Start, Check Ignition Switch
Ignition Switch

But, if the security light flashes on the instrument panel each time the car doesn’t start. That could tell you to begin with checking the security system.

Conclusion

So, as you can see starting issues are not that easy to solve and can be time consuming. Finally, you should consider diagnosing the problem; using a logical method to comprehend the reasons, why your engine cranks but, fails to start.

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