Thursday September 6 2018

Why has my car failed to start?

 

Paul, over the last two days my 1995 Toyota Carina has failed to start and my faithful mechanic cannot figure out why. The car starter turns but the engine will not start. Is the engine due for an overhaul? Sempangi Fred.

Hello Sempangi, your Toyota engine ignition system has a ‘crank no start’ condition. The ignition system relies on a number of components to start an internal combustion engine such as the one on your Toyota.

Some of these components are part of other functions. To investigate a ‘crank no start’ situation, the technician should look at the broader picture, bearing in mind that every internal combustion engine requires spark, fuel, air and compression to ignite and run well. Ask your technician to test for spark at the plug end of the wire using a spark tester. In the absence of spark the positive terminal of the coil should be tested for power supply. The technician should proceed to test the fuel injector pulse or power supply. If the injectors are okay the fuel pressure should be tested and compared with nominal values. The air intake system should be inspected to confirm that there is no leak on the intake tunnel and the throttle potentiometer is working well.

A computer diagnosis can help detect a problem, if the diagnostic technician knows how to analyse and compare actual values with recommended range of values. One must confirm that the camshaft timing is okay or the timing belt has not snapped.

If there are no flags with these checks, then a compression test should be carried out to rule out loss of compression due to internal engine component damage. You should be able to identify the cause of ‘crank no start.

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