no spark troubleshooting

86SS86LS

Member
Joined
Jan 12, 2006
I have a no start condition on my 87 gn, a quick summary of where I am at:
I have injector pulse (verified by noid light)
fuel pressure at 40 psi
ses light is on with key in run position
no error codes

I followed the no-start tree and get to step 3, where it tells me to check ign module or ign mod connection. I've tried 3 different ign modules and get the same result. Because I have injector pulse, the crank and cam sensor should both be working. I checked continuity on all wires that run between the ecm and ign module....all are good. all pink/black wires have 12 volts.

What seems unusual is that when cranking the engine, the dash displays rpm but my scanmaster does not. If I remember correctly, it should display rpm....someone please confirm??? I get 2.4v on B5 CRANK REF HI......which should indicate that the ecm is getting a signal from the Crank sensor. It feels like I'm getting close to figuring this out.....is there anything else I should check at the ign module or ecm with my multimeter? Bypass, CRANK REF LO, est control.......is it possible these could contribute to no spark?

Thanks in advance
 
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No, the scanmaster does not display rpm's when cranking the engine over.

Have you done this to check for spark.

4. Does the ignition have spark? Pull a plug out, put the appropriate wire back on it and lay the plug on the valve cover or hold it to a good ground. Crank the engine. Do you see a good blue spark across the gap? To avoid any fluke of nature, pull each plug wire off and check it for spark on one side of the engine (this will verify that all three coil packs and the module are working).
 
I am using a spark tester with a bulb that plugs in between the plug and plug wire.
No, the scanmaster does not display rpm's when cranking the engine over.

Have you done this to check for spark.

4. Does the ignition have spark? Pull a plug out, put the appropriate wire back on it and lay the plug on the valve cover or hold it to a good ground. Crank the engine. Do you see a good blue spark across the gap? To avoid any fluke of nature, pull each plug wire off and check it for spark on one side of the engine (this will verify that all three coil packs and the module are working).
 
I am using a spark tester with a bulb that plugs in between the plug and plug wire.

Ok, but did you check for spark like this. To verify the coil pack and module are working?

To avoid any fluke of nature, pull each plug wire off and check it for spark on one side of the engine (this will verify that all three coil packs and the module are working).
 
Sorry, I missed what you were getting at. Yes, I tried all 6 wires, no spark.

Ok, but did you check for spark like this. To verify the coil pack and module are working?

To avoid any fluke of nature, pull each plug wire off and check it for spark on one side of the engine (this will verify that all three coil packs and the module are working).
 
Have you checked the fuses?

Is the Check Engine light illuminated when the key is turned to ON? Check the ECM-IGN fuse, the ECM-SOL fuse, and might as well check the CCCI fuse while you are down there.
 
Have you checked the fuses?

Is the Check Engine light illuminated when the key is turned to ON? Check the ECM-IGN fuse, the ECM-SOL fuse, and might as well check the CCCI fuse while you are down there.
yes, light is on with key in run position.
I visually checked the fuses and they are good, I'll check them with a multimeter just for peace of mind
 
How long ago did this condition show up? Was it running fine and you made a change to anything or was it running fine and out of no where just had this happen?

It sounds like a similar issue i had awhile back, but there's a few things that can cause this condition.
Out of curiousity, did you verify the crank sensor hadn't had any of the 3 fins damaged and it was positioned in the bracket properly ( so when the reluctor ring on the crank pulley passes between each fin on the crank sensor that the low and high ref signals are being seen properly by the ECM to trigger spark )? (In my particular case it was somehow the crank sensor being pushed onto the bracket too far where one of the fins wasn't having the reluctor ring pass by it, resulting in the crank sensor sending the wrong ref signal to the ECM and wouldn't get spark preventing the car from starting.)

Have you tried replacing the fuses with known good ones to make sure it wasn't simply a blown fuse causing it?
Have you checked to see if there was damage to the wiring that feeds to the crank sensor under the hood?

Trying to get a better understanding of how it is the car is displaying the behavior currently, to try to offer better help.


Posted from the TurboBuick.Com mobile app
 
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Are you sure you have power to the ignition module connector? It sounds like you don't or all the ignition modules you have tried are bad.

If you have:


no spark, but have injector pulse - Check the Ignition Module (also check the CCCI and ECM-IGN fuses)

have spark, but don't have injector pulse - Check the Cam Sensor or ECM

have no spark or injector pulse - Check the Crank sensor or the Ignition Module (and fuses)
 
How long ago did this condition show up? Was it running fine and you made a change to anything or was it running fine and out of no where just had this happen?

It sounds like a similar issue i had awhile back, but there's a few things that can cause this condition.
Out of curiousity, did you verify the crank sensor hadn't had any of the 3 fins damaged and it was positioned in the bracket properly ( so when the reluctor ring on the crank pulley passes between each fin on the crank sensor that the low and high ref signals are being seen properly by the ECM to trigger spark )? (In my particular case it was somehow the crank sensor being pushed onto the bracket too far where one of the fins wasn't having the reluctor ring pass by it, resulting in the crank sensor sending the wrong ref signal to the ECM and wouldn't get spark preventing the car from starting.)

Have you tried replacing the fuses with known good ones to make sure it wasn't simply a blown fuse causing it?
Have you checked to see if there was damage to the wiring that feeds to the crank sensor under the hood?

Trying to get a better understanding of how it is the car is displaying the behavior currently, to try to offer better help.


Posted from the TurboBuick.Com mobile app

this happened after winter storage.

I'll pull and check the condition of the crank sensor tomorrow. I did take a multimeter to the crank sensor plug and wiring related to the crank sensor. With the key in run, I checked voltage at the crank sensor plug. A has 12V, C has 5V, and 12 volts across A-B. I probed the Gray-White wire at the module connector and get between 4 and 5.5 volts.

The no start tree suggests a 6-9 volt signal from the crank sensor........since I am below 6V do you think that is the problem? If not, it seems that the crank signal is getting to the ign module but not from the ign module to the ecm.
 
Are you sure you have power to the ignition module connector? It sounds like you don't or all the ignition modules you have tried are bad.

If you have:


no spark, but have injector pulse - Check the Ignition Module (also check the CCCI and ECM-IGN fuses)

have spark, but don't have injector pulse - Check the Cam Sensor or ECM

have no spark or injector pulse - Check the Crank sensor or the Ignition Module (and fuses)

yes, I have voltage to the module (12 volts to the pink/black wires)
 
Try and check spark between the towers on the coil. Use a couple paperclips to make a set of leads. Jump from front to back.
 
Try and check spark between the towers on the coil. Use a couple paperclips to make a set of leads. Jump from front to back.
so you are saying test spark across each coil with a light bulb type tester? this won't damage the coil....?
 
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