Waytoomanycars

Hi, I have posted here a couple of times with the knowledge of members proving to have been extremely valuable. So here I go again.....Sorry it’s long but I’ll give you all the information I have to avoid people having to ask too many questions.

I have a 1979 Australian Delivered SA22 RX7 with NA 12a. Rats nest and all the other vacuum / emissions system still in place.

It had been laid up for a number of years when I purchased it and, using the knowledge base on here and elsewhere, successfully resurrected it. It ran fine.....though very Smokey at first!

After the smoke cleared it ran fine, started every time and I began to believe that the horrible stories I had heard of old Rotaries was just a myth!

Then it just died one day!

I eventually got it running again after spending many many hours tracing an electrical fault. A previous owner had cut & soldered an ignition wire to fit a radio or some other thing which had resulted in a dry joint. This now fixed I thought my woes were over.

How wrong I was!

Since then starting has been a nightmare! Previously starting was a breeze!

It will fire but not run (with very few exceptions). It’s like it just doesn’t have any fuel to run for more than a couple of seconds. Though the trailing plugs are soaked with fuel every time.

As it stands.....

Tank is 1/2 full with fresh fuel

Fuel pump flow / pressure tested and OK.

Return line is clear.

Carb cleaned & rebuilt.

Ignition has been checked, timing is correct, points set with dwell meter, hot spark to all 4 plugs. New plugs, leads, coils, points, condensers, cap & rotor!....such is my frustration that I’ve tried everything!

Compression is good.

Battery is new and fully charged.



On the odd occassion that it actually starts it runs well.....but only for about 10 minutes & then it dies and will not re-start!

After a great deal of searching and problem solving I’m now considering an intermittent electrical fault. Specifically the 12v feed to the fuel bowl vent solenoid. As I understand it there should be 12v to this with the ignition on. The manual and all the information I can find in the various forums indicates that this should be fed via a black wire with a white trace which receives its 12v direct from the ignition circuit.....mine is blue (not joined anywhere) and has 0v no matter what.

if I manually jump 12v to this the solenoid activates however somehow this feeds back into the original relay / control boxes on the left hand side of the engine bay rearward of the strut tower resulting in a buzzing from
one of these. I haven’t yet investigated this properly to determine the cause. Manually jumping with the blue wire disconnected from the solenoid activates the solenoid but obviously doesn’t feed back into the loom. I think at this point I’m actually answering my own question......maybe I should just manually jump this connection and see what happens!.....but I’ll see what expertise is out there first!

To fix my original electrical fault I had to undo most of the loom and replaced many of the original relays.....I’m thinking that somewhere in that mess I have missed a connection or connected one of the relays incorrectly!

So, in short, should that blue wire to the fuel bowl vent solenoid have 12v to it and, if it should, why would the relays be buzzing. Could it be that the relays / control units themselves are just faulty?

Any advice on this would be awesome.....I’m at the end of my knowledge base! Help!!!!!!

DummyFixer

Do you have the service manual and wiring diagrams? The download link is in my signature.

Waytoomanycars

Thanks for your reply. I have the Haynes manual that reproduces the wiring diagrams. Unfortunately there are many colours in the wiring loom that just don’t match mine. I imagine that somewhere out there an Australian Supplement exists!

One of the relays is the hot start assist. The colours on this match the UK wiring diagram. I suspect the other is the no longer installed Airconditioning relay.....but the colours match none of those in any of the wiring diagrams. Disconnecting this relay results in the “Heat” warning light on the warning panel going out.......though I can’t find reference to a “Heat” warning lamp on any of the wiring diagrams to enable me to trace this relay!

The relay is simply marked “Japan - 3Points Relay”.

In any event it doesn’t change the voltage to my vent solenoid & manually bridging it makes no difference to starting, however it does open the solenoid! So maybe whatever normally feeds that solenoid also has some influence over starting?

Thanks for the link to all those manuals too. A great source of information!

rxtasy3

iTrader: (2)

link i was going to suggest is already posted.

DummyFixer

If I'm not mistaken, the "HEAT" indicator has to do with a sensor under the floor of the car to warn of excessive exhaust system heat (catalytic converter overheat condition).

Does anyone "down under" have an answer for the wiring color mismatch?

Benjamin4456

A quick comment about the float bowl vent solenoid. It should be powered any time the car is running and is usually enabled with the key in the run position. Without it powered you'll run into all sorts of interesting issues due to the float bowls not being able to equalize pressure with the atmosphere.

Regarding the weird wire colors and buzzing relays, I'm really not sure. Your best bet there will probably be going through the fsm and/or wire tracing as others have already suggested.

Waytoomanycars

Still no luck with this!

I’ve now spent a ridiculous amount of time and effort on this car and am nearing the point where it will be scrapped! This will be the first time in 35 years that I will have to accept defeat! There’s no use spending more time, effort & money with no light at the end of the tunnel.

I believe the problems to be electrical, however attempting to problem solve the electronics on this car without a wiring diagram has proven impossible! It seems that Australian delivered Rx7’s had their own specific wiring loom and electrical system, an apparent hybrid of Californian & UK with a colour coding all of its own.......oh and the connectors don’t necessarily match what appear in the workshop manual! Right now it’s like taking a road trip around Australia using a map of America!

I mention the Californian models as this car seemingly has the Distributor relay, retard relay, short relay and ignition relay in the front left corner near the headlight. These 4 relays only appear on the “California Only” wiring diagrams! Actually identifying which is which is proving problematic as neither the colours nor the connectors match those depicted in the FSM!

Heres what I know.....

Leading spark is good, trailing is there but much weaker. This would match up with Californian Emissions systems as described in the FSM however I would have thought that there would be a good spark for startup.

The ECU has 16 pins......so that’s the generic, non California specific ECU. I’ve opened the ECU, it is clean and free from any corrosion or damage. Fuse is good. There are 2 micro relays in the ECU, only 1 operates when the ignition is tuned on. I assume the second one operates when certain running conditions are met thereby operating the various emission control devices.....unfortunately the ECU is something of a mystery with very little that can be checked without the car running! It gets power, I know that much!

The wire leading back from the bowl vent solenoid is blue, not BW as depicted in the FSM. This traces all the way back to connector X-01 and back through the firewall. 12v is NOT PRESENT at the solenoid or at the corresponding point on connector X-01.

The richer solenoid has a light green wire with a yellow trace (though this may be slightly discoloured so could be light green with a white trace). It can also be traced back to connector X-01, the wire is equally discoloured at this point, nonetheless there is no power to the solenoid. I believe, from the FSM, that this is a switched 12v dependant upon the idle switch being open or closed. It would also appear that the idle switch open will then feed back into the ECU to, I presume, trigger other systems. At this point I should note that the idle switch has been dismantled, cleaned and checked. I am just thinking to myself now that maybe I should test for 12v at the vent and richer solenoids with the switch open and again with it closed....I’ll do that this week!

Of the 4 previously mentioned relays located in the front left corner of the engine bay only the Ignition relay seems to operate! This however “flutters” open & closed as the key is turned to the start position, opening and closing about 3-4 times a second! I would have thought that as power is supplied the normally open relay would close and stay closed while power is applied. Maybe there is a voltage drop during cranking that causes this? I believe this relay provides 12v to the coils during cranking....which I get at both coils when cranking so if that’s the case the “fluttering” doesn’t seem to affect the function. Since observing this “fluttering” I have modified this relay by soldering the internal earth which ordinarily just makes metal on metal contact with the external case, soldering both the internal earth to the case and to an external earth wire.....seemed that the metal on metal was always going to be prone to corrosion!

Turning my attention to the remaining 3 previously mentioned relays:

The distributor relay is powered by the ignition switch and there is 12v present at the BW wire, as it is normally closed this continues to the Trailing coil resistor. External switches visible on the FSM diagram that feed into this are not all present, only the top switch for M/T is present as well as a very different vacuum control switch.....if that’s what it is! I believe these are some of the switches that are responsible for the trailing ignition system not operating at all times, as described in the FSM.

The short relay does not seem
to operate. By the FSM it’s normally open and closes when powered via the ECU, so I assume conditions are not met to do this until the car runs? Interestingly the FSM shows a total
of 4 external resistors associated with this relay however there are only 2 on the car fed by a BR and BL wire at one end and out to the coils (and elsewhere) via a Y and YB.

Finally the retard relay. Again normally closed so not operating with ignition on doesn’t seem too unusual! Seemingly requires input from the vacuum
switch / vacuum control valve to operate and “switch off” the trailing ignition.

So.....I’m at a loss. It will crank, it has spark, fuel & compression, the timing is right. It should run, it should start each and every time!!! Instead It runs infrequently.....almost never. On occasion it starts in an instant, other times it takes forever or just won’t start at all! It soaks the plugs with fuel when it doesn’t start. If it does start it dies quite quickly (sound like the bowl vent) but “jumping” this open doesn’t change anything!

I guess my next point, before abandoning this project, is to try to locate an Australian wiring diagram! Does anyone out there have one? Surely Mazda Australia didn’t just fly blind!!!!!

What I really need is the 1979 Mazda Service department to magically appear in my garage!!!!

Any ideas? Any wiring diagrams? Anyone else had this problem and found a solution? The non-starting means I’m now an expert in de-flooding and have learnt way more about early emission control systems than I thought I would ever need to know!

If you’ve made it this far it’s been a long read! Thanks 😊. Hopefully someone can help!

Maxwedge

iTrader: (1)

This seems like the most problematic troubleshooting thread on this issue, ever. Your going to scrap the car over,.... this? Jesus Christ man, put on a Webber or something before you give up on the whole car.

"There"s no App on my IPhone, I give up".

Maxwedge

iTrader: (1)

Keep ignition-on power to the bowl vent solenoid if you're keeping the stock-ish nikki. Simple as that. I never had enough trouble with this car that I considered scrapping it. WTF?

Waytoomanycars

I should clarify. This car is a project but is only viable if it will run, otherwise there really isn’t much value in it. If it was a really nice car it would be different. The fact it ran was it’s one redeeming feature.

Keeping 12v to the vent solenoid doesn’t help. It changes nothing. If it was that easy I would have done it long ago!

The fact is that at this point this car just doesn’t want to run for more than a couple of seconds. It’s taken way too much of my time, all the usual suspects have been checked and re-checked, I’ve invested about 200 hours in this car.....time I will never get back and time I can not afford!

All I can hope is that someone out there has the magic fix, something I’ve missed, something obscure.....

Maxwedge

iTrader: (1)

Hey, I'm not trying to be a ball-buster. But you're dealing with a 40 year old car, so "not running right" is par for the course. You buy these cars for the look and the history, knowing they will need to be rebuilt. If you want a "ready to run" old car look at 10yo, 100k mile cars. Miata, Honda 2000, 350z, etc.. Buying Any year RX7 you need to be ready for a full rebuild, one system at a time.

Maxwedge

iTrader: (1)

The car without a motor is worth almost as much as the car with a motor. Motors are very easy to replace on these simple little cars. So don't throw it away. Sell it to someone who will pop a new motor in and give it another 20 years on the road. Heck, I'd love a solid shell for when I wrap mine around a tree.

Waytoomanycars

Don’t worry, I won’t scrap it! Despite the frustration it has caused me I’ve invested too much of me in it to scrap it. Yes it is frustrating! Never been more frustrated with a car in my life.....so now it’s just more of a challenge!

Steve Adleman

seems I'm having a similar problem, don't have a solution yet, but i'll post if I know anything.

yeti

iTrader: (1)

What does the Australian forums say? My understanding is Aussies and New Zealanders worship rotaries. I'd check the Australian forums for the wiring diagram. I do think that if there is a difference that we should probably get a copy for archival reasons.

For what it's worth I have a early-mid 79 (10/78) and some of the wiring colors have been a little off here and there but for the most part been in line with the diagrams. Probably just how things were done back then.