Drove the car abourt 1 month ago, ran fine. Went out to the garage to start it up....and i get nothing. It just cranks...and cranks. I haven't done one thing to it since it's been sitting in the garage for the past month. Anyone have any idea's? Fuel pressure is fine....just not getting any spark......

 

Do the basics first. Verify keyswitch voltage at the coil when cranking and that the tach wire is not shorted. Verify that the rotor is turning. See if the tach signal is dead or alive: it should bounce the tach off of "0" when cranking. If tach signal is there, coil, cap or rotor is bad. If tach signal is dead, pickup coil or module may be bad or open/shorted wires causing the problem.

 

well, i took off the cap, rotor, and module. The cap looked completely horrible....i had a few of my buddies look at it and they can't believe the car ever started or ran. It's weird, because it has always started fine...and has ran great. Hopefully, that's the problem...but I'm going to go ahead and replace the cap, rotor, and module.

 

replaced cap, replaced rotor. Had the igntion module checked, it checked out fine. Installed new cap and rotor and the damn thing just cranks. It won't start. Not making much sense...

 

91Z28

Follow Superwiser42 recommendations. Also, check and make sure that you are getting 12 volts at the ignition coil during cranking (Pink wire).

Other possibilities:
VATS module (if equipped) is gone.
Ignition coil is toasted
ECM is not receiving DRP from ignition module due to harness disconnect.

//RF

 

went ahead and replaced the ignition module today...still nothing. Checked voltage at pink wire coming from coil, getting 12 volts. The tach is bouncing off of "0" while cranking. Starting to run out of options and money. VATS?? maybe? is it possible to just quit working?

 

91Z28

1) If you have VATS

VATS system depends on making contact with your key. As cylinder lock ages contact resistance increases or makes no contact at all. Do a search - there is a sticky on VATS and how to get around it.

2) ECM does not see DRP signal from dizzy.

//RF

 

the car has the VATS system, I'll see what I can dig up

what does this mean?

 

For ECM to fire injectors and to control amount of timing it must receive a reference pulse from distributor. If you look at the module that you have replaced you'll see a four pin connector. On the module, next to connector you'll find letters G B R E. Pin R provides a reference signal (DRP) to ECM telling it when (timing advance ) to fire next spark and what the RPM's are. Without this signal ECM will not fire injectors. So - pull a plug wire get an old plug tester and see if you are getting spark just to make sure that your ignition coil is ok.

ECM also takes input from VATS module. If there is no input from VATS it will disable injector control. You can check and see if injectors are being fired by putting a test light or DVM across injector connector.

I did a bit more head scratching after re-reading original post. You'll have to check external ignition coil, two wire jumper harness between dizzy, high voltage jumper between coil and dizzy hat, rotor, and inside dizzy cap contact to rotor.

Disconnect HV jumper from dizzy, crank engine - you should see sparks from dizzy side connector, if not HV side of ignition coil is shot.


//RF

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