Hot Rod Forum banner

blazer has spark at coil and gas no spark at plugs

30K views 29 replies 12 participants last post by  driveability 
#1 ·
My 96 blazer was hesitating around 60 mph and recently completely quit. New fuel pump in it i have spark at the coil but none at the plugs. I take it my problem is in the distributor from what i have read the module is a common problem with these? Is there any way to test this out before buying one? IS there anything else i should check? I called the dealer today they want over 200 for just the module does anyone know if there is a place that sells modules aftermarket? I think i can get a whole distributor for less trhan that on ebay. Thanks would really appreciate it if anyone has any suggestions.
 
#2 ·
Just about anytime a module goes, most go to the local auto parts store and picks up a new one, it lasts about a month, so they go get another one, it lasts about a month, you see where this is going. Anyways, I would also suspect the module, and I would replace it with a GM unit. If you can score one that`s still good in a junk yard or get one on ebay cheaper take that route.
 
#4 ·
If you have spark at the coil then you module is fine. How did you test spark at the coil? If you pulled the coil wire off the distibutor and tested there your coil and module are good. if you don't have spark at any of the spark plug wires then either you have a bad set of wires or distibutor cap is corroded, however you will usually not loss spark at all cylinders with wires and distributor cap. the most likely cause of no spark to all the cylinders would be a bad rotor. the rotor will affect all cylinders the same either with poor spark or in your case no spark.
 
#5 ·
blazer has spark coil gas no spark plugs

don't believe module testing at the store, if it is an intermittent problem the test may not catch it. modules can be affected by temp. and other things. most modules may start working after cooling down then quit again, and work when tested.
 
#6 ·
I tested the coil by taking the coil wire off the distributor and grounding it on the part of the engine and there was a lot of spark then i hooked it back up to the coil and checked my plugs theres no spark there? Wouldent that tell me there is a problem at the distributor? I changed the rotor and the cap looks perfectly fine.
 
#7 ·
Did the metal piece come out of the centre terminal of the cap?

The spark goes from the coil wire, into the cap, though the rotor and out the various terminals, through the wires to the plugs.....it has to be one of those things.
 
#11 ·
All the module does is switch the coil on and off....which it is doing. The problem is either your cap , rotor or wires.....can't be anything else. I think the button is missing out of the cap or the centre of the rotor is broken off, or not touching the button.
 
#12 ·
check the pink and white wires from the coil to the distrib they commonly break inside the insulation and you cant tell just by loooking, wiggle and move them around while someone cranks the engine,

ive had this problem before,

the new harness is 20 bucks

it cause no injection and no spark both,
took months to figure it out

replaced it and it has been great for three years now


we wasted our time with replacing the FP twice and other stuff when it was nothing but a stupid cheapo wire broken
 
#14 ·
If you have spark at the coil then the problem is not the module. The module is what tells the coil to fire. I has to be the rotor or the cap, they are in a hard spot to install so double check they are in correctly and the cap is on tight. I have seen the top contact of the rotor get bent up away from the coil terminal inside the distributor cap cause no transfer of spark to the rotor. Your problem has to be the coil wire not puged in tight, incorrectly installed distributor cap or rotor, or by a long shot all of your spark plug wires are bad.
 
#15 ·
if your actully getting voltage out of the secondary windings of the coil, the fault would be within the coil wire, or the spark is grounding inside the distributor. if you have voltage to the coil, but no spark, take a test light, hook it up to the - side of the coil then ground it, if the light flashes, your getting a signal from the modual, if not, your not getting a signal. you could have the modual tested, if it's not flashing, if it's good check the hall effect/ Magnetic pickup to make shure it's working, a magnetic pickup will generate a voltage, if you spin the motor over, with a dvom hooked up, you can verify it's working by this. the modual is a transistor, when the magnetic pickup/ hall effect triggers, it turns off the voltage to the coil, the magnetic field collapses and induces a voltage into the secondary windings.

Also check the crank sensor, some ign's will not pulse until the modual get a crankshaft position ( MOPAR is big on this ). we just finished up a '95 Jeep that an autoshop was playing parts changer on, it would not start, he replaced hall effect sensor in the dizzy , starter, ASD relay, ignition switch and wanted to replace the PCM. after a little reserch on shopkey, I found that on this jeep, the ignition will not pulse without a crankshaft position, so we tested the crank sensor with a lab scope, and shure enough, it was bad, replaced and it runs good now.
 
#18 ·
I would make sure the center post it the dist is touching the coil and that it is assembled correctly. If you have spark at the coil and not at the plugs there are only a few possibilities.
1 bad coil wire (not very common)
2 Bad rotor, burnt through and shorting out. ( you said it is new)
3 Wrong cap or rotor.

I am guessing this is a small cap hei. Those caps can very easilyy be installed incorrectly and the rotor wont hit the button in the cap.
 
#19 ·
What do you mean by the centerpost of the distributor is touching the coil? Are you talking about the cap and rotor touching? I 'm sure its all installed properly i've has these 4.3 g.m. vehicles for years now and i have changed caps and rotors many times never had a problem. This is just bizzarre the vehicle was acting up prior to it totally dying it was hesitating at around 55 then one day it just cut out totally. I looked under the rotor i noticed some build up on top of the shaft looked like some kind of grime is it possible that could have something to do with it. I cleaned it off but still no change just turns real good but wont fire? Can something be wrong with the actual distributor? Thanks guys i'm just getting really frustrated with this one.
 
#20 ·
Are you sure the rotor is down all the way. make sure you cant turn it. I may have missled you on the assembled incorrectly, I was thinking or the large cap HEI. Have you tried a new coil wire, or at least put a meter on the old one. The coil wire could be broken
 
#22 ·
Doc here, :pimp:

Check the fuse buss, for any blown fuses, ESPECIALLY marked IGN, ECM~1, or INJ...

Also Check to be sure the TACH wire (white) Is not shorted to ground..or the Tach calibration card is not bad, (disconnect the tach and try to start it.)

Doc. :pimp:
 
#24 ·
I gather you have spark and all the other things you need to run the engine, but you have narrowed down the situation to be no spark at the end of the spark plug wires, correct ?
OK, dumb as this sounds and bear with me here, Are you sure/trust in the manner used to test if there is voltage at the end of the spark plug wires?
Static testing a coil only tells you theres spark, it doesn't speak to the quality/power of the voltage. It might just be a week coil that may create a spark but not run an engine.
I would test it in a simple way, with everything connected remove one plug wire at the spark plug. Hover it over a good ground with the lights dimmed so as to see any part of a spark. Hold it as close to the ground as you can without making contact. You may see a small discharge/spark but not enough to run an engine. Its hard to diagnose a problem over the net and often we come to conclusions , but in reality with a lack of product knowledge we miss something simple. I surely would hope the distributor rotor turns smoothly during cranking as well. If you have done this I apologize in advance, just thinking out loud.
John
 
#26 ·
ricksautorestoration said:
Did check all the fuses a couple times they are good. Where abouts is the tach wire i have no idea where to look?

Doc here, :pimp:

It will Be the WHITE wire coming from the Dizzy out to the Tach AND a pin on the Computer..Leave the computer wire on, and Remove the Tach wire for testing (you need the computer ref. Signal to make it run) . So pull the wire at the TACH.

Doc :pimp:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top