hi, i have a '91 miata with starting issues...
now its 130,*** miles. it has new plugs, wires, starter, battery(tested).
the car would start up just fine until i left for a 5day trip. the car started but after a 15~20 min drive, it stalled. the car would crank but wouldn't start back up. tried jump starting, push starting, but no luck. got it towed back home and Ive checked the battery which was tested and has power...
jump wired the diagnosis connector F/P and GND to check the fuel pump and i hear operating sound coming from it. no sign of wear and carbon build up on the spark plugs... all the fuses or okay too...
just cant figure out whats causing my car not to turn over...

help is very much appreciated!!!
thank you!

 

is it still sparking when you crank?

 

haven't done that test yet... do i need a new sparkplug to do this test? thanks!

 

pull a plug out, reattach it to the wire, set it next to the lift bracket, crank motor, watch for spark.

 

thanks.
ill check it today... so if there isn't any spark what can that indicate? ignition coil malfunction?

 

or CAS

 

one bad coil will cause it to run like ****, one bad CAS will cause it to not run at all. Check the connector first.

 

okay, i checked for spark but didn't see any spark...( not sure if i did it right... took out the plug and wire from the first cylinder and had someone crank it?)
anyway... still the car cranks but wont turn over... whats the best way to check the CAS, ignition coil? get one multimeter? thanks!

 

CAS testing (from interwebz/fsm) with a volt meter:

Turn the key to on (don't start the car), you should see the following.

White/Red wire: 12V
Black/Lt. Green wire: ground/0V
Turning engine via wrench read the voltmeter, the White wire and the Yellow/Blue wire should both fluctuate from 0 to 5 volts. Four pulses per rev for the white wire and 2 pulses per rev for the blue/yellow. Turn the crankshaft two revolutions for one CAS revolution.

Connector voltages:
White/Red= 12V
White= 5V
Yellow/Blue= 5V
Black/Lt Green= 0V (ground)

 

The absolute best way to check the CAS is to replace it with a known good CAS.

At least in my opinion.

Got any Miata buddies?

 

mmm... not really. im kinda new with miatas. juat got mine like a month ago. was thinking of getting a multimeter today and check the volts on the CAS...
thanks!

 

put.
location.
in.
profile.

 

hi. sorry for the late update... (i live in Hawaii)
Anyway...
checked battery again=it has 12.51V.
checked resistance on the secondary coil winding=it has resistance between 11.2-15.2kΩ
jump wired the diagnoses mode= nothing flashes...
checked resistance on spark plug= i think it has the right resistance...

BUT STILL NO SPARK...
could it be that the timing belt jumped? or the CAS?

thanks

 

Nah, I'm sure the CAS could have nothing to do with it.

 

how many teeth are supposed to be between the cam gears? any info will help! the car was running fine till it suddenly stalled... and ever since it wouldn't turn over any more... running out of clues...

 

Udude have you read the post just before your last one. There should be 19 valleys on th belt betwnne the two maks on each cam pully. Even if th ebelt is off a tooth it would still run. Why dont you take the advice that has been given and then come back and tell us what is going on.

Good luck,
Jared

P.S. You still havent updated your location.

 

Uh, maybe the CAS? Hint, hint. Diagnosis is complete.

 

thanks for the help.
i tested the CAS connector and read:
Connector voltages:
White/Red= 12.41V
White= 70.02mV
Yellow/Blue= 71.02mV
Black/Lt Green= 0V

so that means bad CAS?

thnks...

 

Is that peak voltages when turning the CAS?

With number of pulses per rotation as astroboy mentioned?

If so then CAS.

 

... apologies for my stupidity... but how do you exactly test the voltages when turning the CAS? do i test the CAS with the connecter connected?
thanks for all the help...