Wont start

  • 2003 MAZDA 6
  • 160,000 MILES
The car started after a jump and would not hold a charge so I replaced the alternator and changed spark plugs everything worked fine went to work next morning started right up drove to work no problems get off work ten hours later car would not start just cranked. I towed it home replaced fuel pump, still does not start. I replaced the camshaft position sensor still, does not start and when I crank it makes a funny noise now and try's to turnover, but still does not start.
Do you
have the same problem?
Saturday, July 23rd, 2016 AT 7:43 PM

1 Reply

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can only be tested during the failure. Any other time and they will simply test good because the problem is not present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That is what we have to look for.

These are the basics that need to be tested and will give us the information required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the positive terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.
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Sunday, July 24th, 2016 AT 5:17 AM

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