sirfixalot

I have a 1985 GS with the 12a engine. The car had been starting fine, until I replaced the radiator and thermostat. The first time I attempted to start the car after the radiator installation the engine would turn over but not fire. I have experienced this will fouled spark plugs, so I removed and cleaned the plugs, but the car still wouldn't start (the lead plugs were dry, but the trailing plugs were moist, and smelled of fuel). I tested the spark at each plug using an inline spark tester positioned between the spark plug and plug wire, and I am getting a spark on both of the trailing plugs, but no spark on either lead plug. I swapped the ignition coils to see if one might be faulty, but the situation remained the same. Is it normal during starting for the top plugs to receive a spark, while the bottom plugs do not? I can't imagine a direct connection between the radiator/thermostat installation and ignition issues, but since one directly followed the other is it possible that while performing the installations that I might have inadvertently altered or damaged some ignition related component located nearby?

GtiKyle

iTrader: (5)

You checked your coils, but did you check the ignitors? They commonly fail, so you can try swapping them around and see if the leading plugs start sparking.

sirfixalot

Thanks for the tip. Fortunately, my Rx7 has performed trouble-free for most of the years that I've owned it, so I don't have much experience working on it. Do you happen to know where the ignitors are located, or what they look like?

GtiKyle

iTrader: (5)

No worries.

If you look at your distributor, there should be two plugs attached just below the cap. Those two small modules are the ignitors. I recently was working on my car, and bumped the plug on the ignitor and was getting no ignition. Plugged it back in and boom. Fired over. So start there.

You can try swapping them around and see if that changes which plugs are getting spark.

fastissimo

Also may want to check if the leading coil is getting 12v

sirfixalot

Thanks for taking the time to be so helpful.

sirfixalot

I will do that, thanks for the tip.

ray green

iTrader: (14)

On swapping the ignitters, it is easier to just swap the leads on the igniters than to remove and physically swap the igniters themselves from on position to the other.

Also less chance of damaging the igniters or more critically the interface between the igniters if you don't remove them.

Manny3

iTrader: (1)

Igniter was my issue last week.

mazdaverx713b

iTrader: (91)

You will have to physically swap the ignitors. If you swap the leading and trailing out and notice you have no tach bounce then you can pretty well confirm that the ignitor that you swapped into the trailing position from the leading position has failed.

Once you replace the ignitor, clean the rear of the new ignitor if its used, and clean the corresponding mounting point on the distributor. Then apply a small amount of thermal paste to the new ignitor where it mounts against the distributor. Then you are safe to install the ignitor. I would do this to both ignitors.

raven12aFB

I was just dealing with that problem. I had no spark on the leading coil. I swapped the ignitors from position and it was the leading ignatia that was dead. I swapped the ignitor with one spare that I had and problem solved.

Now if I can get her to start🤦‍♂️......but that will be for next weekend .....2nd round!

sirfixalot

Thanks for the tip.

sirfixalot

Lots of helpful information, thank you.

sirfixalot

I hope that I get the same results, thanks.

raven12aFB

Good luck....

sirfixalot

I swapped igniters and the spark moved from the trailing plugs to the leading plugs. I have ordered a replacement igniter. Thanks so much for the help.

sirfixalot

I swapped igniters and the spark moved from the trailing plugs to the leading plugs. I have ordered a replacement igniter. Thanks so much for the help.

raven12aFB

Cool....glad you could figure it out. Like I said...i was dealing with the same problem and that process got the culprit......bad ignitor also...luckily I had one spare hidden in my tool box....

mazdaverx713b

iTrader: (91)

Glad you got the issue figured out!! Remember to use a small amount of thermal paste on the ignitor backs. You will be back in business in no time at all! Did you order one or two ignitors?