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Index > Engine/Drivetrain > Thread: Ignition Issues 1974 REPU
Thread: Ignition Issues 1974 REPU
chocolate_supra


Newbie
Posts: 2
posted May 03, 2018 09:42 PM

Ignition Issues 1974 REPU

Hello, everyone! I just bought a 1974 REPU and am having a little trouble getting it to start. After a bunch of troubleshooting, here's what I found:
With the key ON I get around 9-10V on the (+) side of each coil. With the key in START, however, the power drops significantly (almost to nothing) on the trailing coil ONLY, while power remains good on the leading. I've checked some simple schematics (my REPU shop manual doesn't have a full wiring diagram for some reason) and believe it to be a faulty ignition relay. Does this sound right to yall, and if so, where on earth do I buy one?
Is there anything else I should be checking? When I crank the engine I get good, strong spark on the leading plug wires but none on the trailing so I think this is the reason it doesn't want to fire up. Any advice would be greatly appreciated.

       
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Brad


Rotorhead
Posts: 1671
posted May 12, 2018 02:53 PM

I ran a new + power wire from the fuse box to one coil. And a simple jumper wire to the other coil. Larger gauge, less voltage drop over the wire, fresh connections. Like a 10 gauge.

Relays are typically working or not, but you never know.

You need a solid 12.6 volts at both coils.

You could start by just cleaning all the connections with a wire wheel and brake cleaner.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Brad


Rotorhead
Posts: 1671
posted May 12, 2018 03:00 PM

You can run the car on just the leading ignition. Heck, I've run it on just the trailing ignition when the leading coil broke.

       
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chocolate_supra


Newbie
Posts: 2
posted May 12, 2018 04:09 PM

I like the sound of that, super simple. But won't sustained 12v cook the coils and points?

       
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terraphysics


1st Gear
stock
Posts: 19
posted May 12, 2018 04:28 PM

Have you checked the compression on the rotors? To get an accurate reading you need a special gauge, but one can get an indication of the compression with a normal gauge. Apex seals may be broken or stuck after the engine has been sitting for a long time. An injection of ATF can boost the compression to get it started, the engine will smoke a lot until it burns off

         
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terraphysics


1st Gear
stock
Posts: 19
posted May 12, 2018 06:17 PM

Follow up on my previous reply.. Here is a link to using a standard compression gauge to test rotary engine compressions, good video, shows both what to expect from good and bad seals.
https://www.youtube.com/watch?v=_jOLN-AGQO0
Here are some links to using ATF to free up the seals ( correction from my previous statement, the ATF doesn't boost the compression , but frees up stuck seals that can then restore the compression).
http://www.mazspeed.com/atf.htm
https://www.rx8club.com/series-i-tech-garage-22/another-how-fix-compressions-any-rotary-engine-atf-170689/

         
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Brad


Rotorhead
Posts: 1671
posted May 17, 2018 11:51 AM

quote:
I like the sound of that, super simple. But won't sustained 12v cook the coils and points?


Oh i presumed uyou had the electronic igniton from an rx7, everyone upgrades to that. Not sure if points can handle 12v

       
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