Mazda: No spark, crank sensor, mazda dealer

Question
QUESTION:  2001 miata, parked it friday night. returned Monday night and have plenty of crankover but no start. I pulled one plug, seems wet and smells of gas. held it against block and cranked, no visible spark. Is there any way of troubleshooting the exact source of the failed spark without "bringing it to the dealer along with a blank check?" This ignition system seems to me, to be a "black box" I have lost all faith in the local mazda dealer service dept.

ANSWER: Check for spark on more than one cylinder.  1 & 4 are paired off and 2 & 3 are paired off.  If there is no spark on 1 then there will be no spark on 4.  Same for 2 & 3.

If there is no spark on any then the next course of concern would be a crank signal.  Two sensors camshaft position and the crankshaft position.

If either have failed the MIL (malfunction indicator lamp) will be lit.  A code will be present to help determine which has failed.  They both do fail from time to time the crank sensor being more common.  The run between $95 and $125 each.




---------- FOLLOW-UP ----------

QUESTION: Can the code be read without a special monitor? i.e. several key on/offs?  It is hard to say whether the MIL is lit because the engine does not start and all the indicators are on before start. This is really a lot of help and I can perform the tests you indicated tonight. Thank you

Answer
When you initially turn on the key the system will perform a test after a few seconds the MIL will go off unless it has a fault.  You will need at least a generic ODB2 scanner to test the system and obtain a code.  You may be able to rent one from a local auto parts store.  If so try to get one specific for Mazda  or Japanese.  The scanner will be able to reset the light.