FarNorthMotoring

iTrader: (2)

Hello, I have been lurking here for about three months and never really posted.

Right now it is sitting beside the freeway on the way to my house. Which I will go after about 4 hours from now.

I bought a 85 FB w/12a for my work car and with plans of restoring it one of these days. It has 123000 on the car and was taken pretty good care of from the last owner. I have changed the Distributor Cap and Rotor, new plugs and wires. Of course the oil changes. That is the only thing I have done to the car since I have owned it. Up till a week ago the car ran great pulls hard for bone stock 12A car.


About week ago the Tach started acting crazy, it would all of sudden stop working and start working again. I passed it off as one of those things I will fix later. Then a couple of days later the car just quits firing as I was driving 40 MPH I left the car in gear and it fires right back up with no trouble what so ever. About 2 miles it does it again and I pull over and motor over the engine for good minute and finally start up (with no cloud of smoke like it does when its flooded). I have been so busy this weekend I didn't even think about it. It drove fine all weekend., Till my way home from work. Does the same thing. I pull the plugs to see if I am getting spark. I had to have motored this engine over a good 5 mins with in 30 min time frame. But when I pulled my plugs I expected it to covered in fuel.... it wasn't. We pulled the air filter cover off to try to see in the dark if it was getting fuel. The car fired up ran rough, but then throw a cloud of smoke like rotary engine does if it has been flooded. Drove great for 100 feet and died.

At first I was thinking it was ignition problem due to the way the tach is acting. I am starting to think it is a fueling issue now. And I have two problems... a fuel delivery problem and electrical problem with my tach.

I don't know when the fuel filter was last changed and I think thats where I am going to start my trouble shooting.

But if any of you guys have some tips or solutions I would be a happy man.

Thanks for your time.
M. Beaver

Pele

iTrader: (28)

The tach runs off the signal generated by the trailing ignitor. The car will run rough, if at all, without trailing ignition. So if the ignitor is bad, you won't be getting spark.

The ignitors are the small black devices located on the side of the distributor housing. You will have to remove the alternator to get at the trailing one. Try swapping them and see if it'll run.

Ignitors are highly expensive new. I suggest getting them seccond hand. I know I need a set.

You can get them from any 1981-1985 RX-7, 12A or 13B engine. They are j109 type. THe 1980 model has j105 type ignitors that are seperate from the distributor. They won't work without some creative wiring.

As for the fuel issue, Try disconnecting the fuel feed line from the carburetor and having someone turn the key. Drain it into a cup or something.

cjf

iTrader: (1)

If I were you , I would change the fuel filter..it could also be your fuel pump...It is kinda hit and miss but do the fuel filter first...see how that goes. I would also change your tranny and rear end fluids...who knows when it was last done...use RED LINE fluids..it is the best. and, if you habe a GSL , you have the LSD rear end and make sure if you DO NOT use red line oil in the rear end, make sure you put the LSD additive in the rear. Hopefully you know what I am talking about. RED LINE already has the additive in it. Most "7" owners use Castrol 20w50 motor oil(don't use synthetic oil) while adding a little Marvel Mystery oil in with the oil ( I'd say a half a qt.) The rx7 loves Marvel mystery oil . Use only regular gas...the "7" doesn't need or like the other gas......oh...and to back up a bit...check your air filter, make sure it is clean...and you may need to have the carb. checked out if the fuel filter and/or the fuel pump does not solve the problem..these are just a couple things ...hopefully, others will contribute to help you out...cjf

FJ

It's likely the two are related. As already mentioned, the signal for the tach comes from the trailing coil (igniter). If you lose the trailing ignition on the '84/'85 engines, the ECU kills the fuel pump.

I would guess that when you said the tach stopped, then started working again, that it had only stopped for a moment. During that time you would have been running on the fuel in the bowls. (If it was longer than a moment, then it gets interesting.)
With any luck, you will just have to clean the connections on the coils to regain fuel and trailing spark. (Do you feel lucky? )

You mentioned you pulled the plugs to see if you were getting spark, but you didn't say if you had leading or trailing spark at the time.

Not related to the problem:
Along with the fluids already mentioned, it would be wise to rinse the cooling system and replace the coolant and water (use distilled water). It should be done every year to prevent corrosion as it's a common cause of water seal failure.

Also, the fusible link connectors should be cleaned as preventive maintenance. They can cause a number of problems. If you are not familiar with them, a picture can be found in this thread:
https://www.rx7club.com/forum/showth...hreadid=104450

-John.

FarNorthMotoring

iTrader: (2)

Update: The car is back in the car port and I am driving the turbo DSM the rest of the week. I wish I had my Miata back together though... That money pit is different thing all together.

Basically like I said I never had any problems with the car before last week. I was just driving along and the tach was going crazy and it would just 0 out completely. Though drive fine and the tach would start working as advertised.

But a couple of times when the tach was dead the car would die out too.

If I can find my Haynes Manual I will see if there is test for the ignitors and look at the fuseable links also. I am too busy to mess with the car this week, its going to have to be this weekend.

But thanks for tips guys.

Spieder

Grab a timing light and check to see if your ignitor is dying when you loose your tach. If it is, you'll get now flashing off your timing light on your trailing (or leading) wire.

Here is some circuit logic for your car. Both your oil pressure guage and tachometer share the same 12 volt node. If it's a power type of failure then the oil pressure guage would also faulter. The signal for the tach comes from your trailing ignitor (I believe).

My guess is you have a bad ignitor. They usually work when the cars cold and stop after a little bit of driving. You can try reversing the coil leads going to the cap. See if that get's your car started.

FarNorthMotoring

iTrader: (2)

I tired reversing them today and nothing. I might go out and see if I can get the tach to die and put a timing light on it tonight.

Thanks.

jerij

iTrader: (5)

The only time my tach did what yours is doing was when one of my fusible links was almost pulled out. Found it by mistake but it got my car off the side of the road.

jerij

FarNorthMotoring

iTrader: (2)

Where is the best place to buy ignitors also? Is that Mazda dealer only part?

gamble302

the best place would be on the forum actually. i bet a few people have one or two layin around. i think i do actually but i have no clue where it is. if nobody else replies sayin theyve got a few they use as paperweights or somethin i'll see if i can find mine. i used to have 3 extras as i was gonna do the dlidfis but i sold 2 to a forum member in need for cheap so i should have the other laying around. j-109's is what theyre called

gamble

Spieder

Na, Kragen's sells them for like 200 bucks each. Best place is a junk yard, get the whole distributer. The Haynes manual also has a section where they describe how to check the ignitors. Something about measuring resistance I think.

Pittdp

I would replace your negative cabl, get new ignigters from Napa for 125 a piece and also put a new positive cable on.
My car would just die on me out of no were and it was a bad negitive cable.

RotorMotorDriver

iTrader: (1)

My car died the other day turning a corner and then I hit the key while I was still moving and my volt gauge dropped to 8 volts...I just popped the clutch and kept going, but I know I have a problem with my negative battery cable...The stock connector is so worn out big, it barly tightens down over the terminal...I bet I just need to fix that and that will fix my problem . Ive also walked out to my car from eating at Taco Bell or something and it act like a dead battery, only nothing was wrong when I parked it. I just get out, wiggle the cable, and off I go . So I bet it dying was just that damn cable . Thanks for the tip.

~T.J.