12a tach dies and car losses spark?
#1
Junior Member
Thread Starter
12a tach dies and car losses spark?
It's just like the title says. I'm getting intermittent spark and the tach dies right before. Any ideas? I'd rathe not replace ignitors and coils if there's another issue. I wa plauing with my dizzy just now and got a mild spark when I retarded it a little... then the engine died again. Pls help!
#2
Junior Member
Thread Starter
Quick update. I replaced my coils with what I thought were known good ones and took it for a 10 m8nute industrial area run. All seemed well so I headed out on the street and the tach goes to zero again right before the engine died 2 minutes later. Now I'm stranded at a gas station.
#3
ancient wizard...
Sooo,problem not likely ignition coils. A VERY common failure pattern of an igniter is loss of spark when warm(hot) and when cooled down will run normally til heat soak duplicates the problem again.
The tach signal is generated by trailing ignition and while your car will run without trailing ignition,it won't for long as trailing also triggers fuel pump circuit and when float bowls in carb empty the car will shut off.
There could be other problems with wiring,personally suspect failing igniter is at the heart of this complaint. Suggest obtaining a known good used one or a new one and replacing it and retest.Even if this is not the cause of the problem,having a spare igniter in your possession is never a waste of money. Own this car long enough and you will have need of it.
Don't neglect scraping off old thermal paste and coating back of replacement igniter with fresh thermal paste,omitting this step guarantees a short life of the replacement. Post back your findings/results.
The tach signal is generated by trailing ignition and while your car will run without trailing ignition,it won't for long as trailing also triggers fuel pump circuit and when float bowls in carb empty the car will shut off.
There could be other problems with wiring,personally suspect failing igniter is at the heart of this complaint. Suggest obtaining a known good used one or a new one and replacing it and retest.Even if this is not the cause of the problem,having a spare igniter in your possession is never a waste of money. Own this car long enough and you will have need of it.
Don't neglect scraping off old thermal paste and coating back of replacement igniter with fresh thermal paste,omitting this step guarantees a short life of the replacement. Post back your findings/results.
The following users liked this post:
David Chan (04-27-18)
#4
Junior Member
Thread Starter
Sooo,problem not likely ignition coils. A VERY common failure pattern of an igniter is loss of spark when warm(hot) and when cooled down will run normally til heat soak duplicates the problem again.
The tach signal is generated by trailing ignition and while your car will run without trailing ignition,it won't for long as trailing also triggers fuel pump circuit and when float bowls in carb empty the car will shut off.
There could be other problems with wiring,personally suspect failing igniter is at the heart of this complaint. Suggest obtaining a known good used one or a new one and replacing it and retest.Even if this is not the cause of the problem,having a spare igniter in your possession is never a waste of money. Own this car long enough and you will have need of it.
Don't neglect scraping off old thermal paste and coating back of replacement igniter with fresh thermal paste,omitting this step guarantees a short life of the replacement. Post back your findings/results.
The tach signal is generated by trailing ignition and while your car will run without trailing ignition,it won't for long as trailing also triggers fuel pump circuit and when float bowls in carb empty the car will shut off.
There could be other problems with wiring,personally suspect failing igniter is at the heart of this complaint. Suggest obtaining a known good used one or a new one and replacing it and retest.Even if this is not the cause of the problem,having a spare igniter in your possession is never a waste of money. Own this car long enough and you will have need of it.
Don't neglect scraping off old thermal paste and coating back of replacement igniter with fresh thermal paste,omitting this step guarantees a short life of the replacement. Post back your findings/results.
#5
Junior Member
Thread Starter
Sooo,problem not likely ignition coils. A VERY common failure pattern of an igniter is loss of spark when warm(hot) and when cooled down will run normally til heat soak duplicates the problem again.
The tach signal is generated by trailing ignition and while your car will run without trailing ignition,it won't for long as trailing also triggers fuel pump circuit and when float bowls in carb empty the car will shut off.
There could be other problems with wiring,personally suspect failing igniter is at the heart of this complaint. Suggest obtaining a known good used one or a new one and replacing it and retest.Even if this is not the cause of the problem,having a spare igniter in your possession is never a waste of money. Own this car long enough and you will have need of it.
Don't neglect scraping off old thermal paste and coating back of replacement igniter with fresh thermal paste,omitting this step guarantees a short life of the replacement. Post back your findings/results.
The tach signal is generated by trailing ignition and while your car will run without trailing ignition,it won't for long as trailing also triggers fuel pump circuit and when float bowls in carb empty the car will shut off.
There could be other problems with wiring,personally suspect failing igniter is at the heart of this complaint. Suggest obtaining a known good used one or a new one and replacing it and retest.Even if this is not the cause of the problem,having a spare igniter in your possession is never a waste of money. Own this car long enough and you will have need of it.
Don't neglect scraping off old thermal paste and coating back of replacement igniter with fresh thermal paste,omitting this step guarantees a short life of the replacement. Post back your findings/results.
Last edited by David Chan; 04-28-18 at 08:33 AM. Reason: spelling - gm geo to gm hei
#6
84SE-EGI helpy-helperton
Running it like that will be hard on the Apex seals with the timing so far off. Fix the leading ignitor and time it correctly before you start applying load. Turning the distributor to its max to get trailing to run the engine is a recipe for disaster. You could have bypassed current to the fuel pump to get it running, as well. Something to consider as a fuel cut switch, aka anti-theft device.
#7
Junior Member
Thread Starter
Running it like that will be hard on the Apex seals with the timing so far off. Fix the leading ignitor and time it correctly before you start applying load. Turning the distributor to its max to get trailing to run the engine is a recipe for disaster. You could have bypassed current to the fuel pump to get it running, as well. Something to consider as a fuel cut switch, aka anti-theft device.
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#9
Junior Member
Thread Starter
I wired the HEI in place of the leading J109 that I binned. With the hei plugged into the leading there's a bit of a tick like an arc. If i put my finger across B and C on the HEI I get a very minor shock. The idle stabilized to 900 rpm when I advance the trailing vacuum pot and the motor still likes full advance but it'll run at halfway with less power. I drove it home now at basically full leading and trailing advance. I laid into it a bit and it has a vicious amount of power. it's just above freezing here in Toronto, so that's a plus for power. It sounds very angry. I'm going to mess with it some more tomorrow. Any insights would be much appreciated.
#10
Have RX-7, will restore
iTrader: (91)
My advice is on par with the above. Set the timing to spec and NEVER run the engine on the leading or trailing ignition alone. Personally, I would have just picked up a set of J109's and left the ignition system alone. They are built well and are reliable. There are plenty of people here on the forum that have sets that they would have sold you.
#11
Rotary Enthusiast
I wired the HEI in place of the leading J109 that I binned.
#12
Waffles - hmmm good
iTrader: (1)
You can not go wrong with the HEI/TFI coil setup. Makes a world of difference.
Also, you can run just leading alone with no issues. The trailing just helps to reduce the stink. I did it for a a few years when I did my HEI conversion, always started well and ran well.
Also, you can run just leading alone with no issues. The trailing just helps to reduce the stink. I did it for a a few years when I did my HEI conversion, always started well and ran well.
#13
1st-Class Engine Janitor
iTrader: (15)
Running leading and trailing is more thermally efficient, but running lead alone is not unsafe for the engine. Might make your cats get pretty hot, though, if you still have them; rich exhaust will do that.
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