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Topic Review (Newest First)
02-15-2007 08:30 AM
driveability
Quote:
Originally Posted by ricksautorestoration
Hey John thanks a lot your right static testing the coil doesent really tell you much the spark looked great comming from the coil but i guess there wasent enough to actually fire the plugs. I swapped coils with my other 4.3 it fired right up. I guess these quick tests arent always the best thing. Anyway thanks to everyone who gave me suggestions this site is great there sure is a lot of knowledge here. Thanks again to everyone.


Rick
Glad to here the forum could help you out.
John
02-14-2007 09:34 PM
ricksautorestoration
Thanks John

Hey John thanks a lot your right static testing the coil doesent really tell you much the spark looked great comming from the coil but i guess there wasent enough to actually fire the plugs. I swapped coils with my other 4.3 it fired right up. I guess these quick tests arent always the best thing. Anyway thanks to everyone who gave me suggestions this site is great there sure is a lot of knowledge here. Thanks again to everyone.


Rick
02-10-2007 06:42 PM
NorthStar If youve replaced all those things cap, rotor, wires, plugs. And have spark at coil wire. It has to have spark at plugs.

Just as an expirement hook everything up to run and give it a shot of ether or gasoline see what it does then when you crank it.
02-10-2007 05:44 PM
docvette
Quote:
Originally Posted by driveability
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
Doc here,

What I do to test, Is get a portable METAL vise, put a plug inside it, and run a jumper cable to the ground at the battery, plug it into the car one cylinder at a time..Crank and monitor the plug gap..look for any kind of a spark at each.

If not, use a KNOWN good plug wire, from the dizzy to the vise plug..see if that doesn't provide spark..If so, you need wires.

Also, Be advised: There WERE a bunch of bad rotors out there, I think NAPA got most of them, where the Tang and the rotor arm weren't making contact under pressure (bad injection molding) so ohm that out while moving the tang up and down. it should not stray off "000" ohms.

Doc
02-10-2007 05:38 PM
docvette
Quote:
Originally Posted by ricksautorestoration
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,

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
02-09-2007 10:27 PM
ricksautorestoration Yes the rotor turns freely i checked that. I will check a plug wire tommorow like you said the spark does seem strong at the coil but ya maybe its not enough to actually start the engine. Its sure worth a try hec i'll try anything at this point. Thanks
02-09-2007 10:17 PM
driveability 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
02-09-2007 09:42 PM
ricksautorestoration Did check all the fuses a couple times they are good. Where abouts is the tach wire i have no idea where to look?
02-09-2007 09:37 PM
docvette Doc here,

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.
02-09-2007 08:52 PM
ricksautorestoration yes i have tried a new wire on the coil and even an old one of my other 4.3. the rotor is right down it is the large cap the screws wouldent go in if it wasent all the way down. I really dont know what to try next i'm at a loss with this thing.
02-09-2007 08:28 PM
T-bucket23 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
02-09-2007 07:35 PM
ricksautorestoration 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.
02-09-2007 07:09 PM
T-bucket23 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.
02-09-2007 06:14 PM
poncho62 That is an odd one.............Are you sure the centre piece on the rotor is touching the centre button in the cap?
02-09-2007 06:08 PM
ricksautorestoration Well i'm at a loss here i just changed the rotor and cap again theres no way 3 rotors and 2 caps can be screwed? The only other thing i can do is change my plug wires but i cant see all my wires being screwed, there actually fairly new wires. This is really frutrating.
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