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2003 Mazda 6 cranks but no spark

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Jul 14, 2014, 5:09 PM

Post #1 of 3 (2591 views)
2003 Mazda 6 cranks but no spark Sign In

replaced the coil pack due to scan saying it was bad now it has no spark put old coil pack back and still no spark

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 14, 2014, 10:37 PM

Post #2 of 3 (2561 views)
Re: 2003 Mazda 6 cranks but no spark Sign In

First, understand that the computer doesn't identify defective parts. It merely identifies a specific situation in a circuit. The actual cause has to be determined.

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 isn't 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's what we have to look for.

These are the basics that need to be tested and will give us the info 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 + 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.


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Ultimate Carjunky / Moderator
Discretesignals profile image

Jul 15, 2014, 12:27 AM

Post #3 of 3 (2556 views)
Re: 2003 Mazda 6 cranks but no spark Sign In

replaced the coil pack due to scan saying it was bad now

I'd like to know which scanner you have tells you which part is bad on your car. Seeing how it was wrong in its diagnosis, I guess us techs can sleep a little easier.

Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.

(This post was edited by Discretesignals on Jul 15, 2014, 12:28 AM)

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