'84 Won't start - Help, roto-wizards!
 

I just bought my son an '84 RX-7 GSL, 70 cu. in. non-turbo, carbureted, five-speed. It ran fine for the first couple of hours, then began dying at the most inopportune times. It appeared to be a case of fuel starvation. I replaced the fuel filter, then the fuel pump. Still no luck. Replaced the spark plugs, plug wires, distributor cap, and rotor. The car miraculously started up and ran like a champ. (You've never seen a bigger smile on a sixteen-year-old's face!) We drove it around the neighborhood (close to home, of course) for an hour or so, and it purred like a kitten. I turned him loose with it, and two hours later he was sitting at a traffic light. The light turned green, and the motor turned OFF. And hasn't run since. I towed it back to my house, and spent all evening troubleshooting it.

The starter spins the engine, but it won't start - unless I pour a little gasoline into the primaries of the carburetor. Then it starts instantly (obviously, we have spark) and runs for three or four seconds until the fuel is consumed. After numerous unsuccessful attempts to start the beast, I became concerned that it was flooded. I removed the plugs, dried them, spun the engine for several seconds with the plugs out, then reinstalled everything. No joy.

I unplugged the connector for the electric fuel pump, connected my voltmeter, and turned the ignition on to check for power. Zero, zip, nada. Methinks I've got an electrical problem.

This is my first rotary-powered vehicle, and I'm not familiar enough yet with the electrical system to know where to look first (though it appears I'm gonna become intimately familiar with it rather quickly).

Please help! Any assistance would be greatly appreciated!

Kevin

Does the tach stop working a little while before the engine dies? The fuel pump relay is switched by the ECU and only sends power if the engine's turning. The ECU knows if the engine is turning from the tach signal, which comes from the trailing ignition. If the tach dies at the same time it's usually because the trailing ignitor is dead. They're easy enough to change (swing alternator up out of the way, unplug a connector, and two screws holding it to the side of the distributor)

Sounds like you've been there before...the tach does stop registering immediately before the engine dies.

What the heck is an ignitor? I know they use 'em in jet engines - is that why RX-7's are so fast???

Like I mentioned in my initial post, I'm an absolute Wankel newbie, so I'm not familiar with the specifics of the hardware yet...

The ignitor is a little electronics gizmo that takes the signal from the distributor and sends power to the ignition coil. Japanese cars call them ignitors/igniters, American cars call 'em modules.

When it dies, the trailing coil stops working, which means the tach stops working, which means the fuel pump stops working, which means the driver starts swearing :)

It's a not uncommon failure. When I picked up the '85 it had a dead trailing ignitor, fortunately I had a spare distributor with at least one good one, took about 5 minutes to swap out :) The only trick is the trailing ignitor is right next to the alternator, so the alt has to be swung up out of the way.

I think I can handle the alternator. Thanks for your suggestions - I'll give 'em a try tomorrow - er, I mean later today...dang - I've got to get up for work in four hours. <sigh>

One last thing: Do you know of a good online manual for the RX-7?

Not a manual per se, but good reading:

http://mrmazda.members.atlantic.net/

A little tricky to navigate but a must-read for those new to the rotary world.

this should also help you out on finding out where things are

http://www.mazdaformance.com/


although you dont know much about rotarys you obviously know engines and basic trouble shooting,
which believe it or not is more then alot of people know that scramble in here for answers

I hate telling people to do the basics that should have been done in step one,

anyway i have a spare ignitor if you need one and would be willing to part with it for $25.00 shipped if its worth it to you,

mazdatrix charges $500.00

my ignitor came from my car so its gauranteed working,

dont need it with dlidfis

more info,,,http://mrmazda.members.atlantic.net/cfaqtext.html
. http://pittdp.homestead.com/underhood.html

If it starts when you pour gas in, then it's probably either the fuel pump relay or the fuel pump. Check those out and make sure they're working.

Folks,

I 'preciate your advice and suggestions!

I haven't seen any mention on any of the RX-7 sites that I've been cruising of a performance-oriented website that I visit regularly for Supra items:
www.mvpmotorsports.com

These folks are located just outside of Fort Worth, Texas, and appear to have a very loyal and vocal band of customers. You might want to check 'em out for all of your RX-7 equipment needs...

Thanks again, and I'll update y'all on my progress!

Kevin

check your screens in the carb also. i don't understand why it would be electrical if he can pour gas into the carb and it works. sounds like fuel delivery. was the car sitting? mine had a gummed up tank and lines. also did you get a see through fuel filter? if you have rust/gunk in the tank it could run for a while until it stops up again. if you can't tell i've been here. replaced the fuel line because it had rusted. replaced the pump, see through fuel filter, new tank.

HEHEHEHEE.... I wonder why there are so many texans with RX-7's.... maybe its cause they dont die of rust down here:noyes: .... Well..... hmm.... So... did it sit for awhile before you got it? If so.... clean all the fuel lines.... vatt the tank, and rebuild the carb.....:)

But it could also be the trailing ignitor...... or an electrical problem.....and those suck.... :noyes: :D









WELL..... LATERz, Andrew

"...check your screens in the carb..."
"...rebuild the carb..."

Man - I HATE carbs! I grew up rebuilding Holley and Ford carbs, and I hated 'em then, and swore I'd never rebuild another carb when I grew up...

Hey wait - I HAVE grown up, and now it's time for a new generation to come to appreciate the joys of fuel injection! I'll make my son rebuild that turkey!

:D HAHAHHAA... :noyes: these are easy to mess with.... I did work on my intake, and carb.. it was not hard at all... when you have the forum that is:) Hey get on AIM... ... I am rotaryrx7toy on there........


LATERZ, Andrew

Check your fuel pump and wiring. I'm thinking it's a fuel delivery problem, because you say it starts up right away.

I can't believe nobody's mentioned it yet. If you plan on setting the computer outside or wasting paper printing out manual sheets, then the online .pdfs are the way to go. If you prefer an old style portable manual, you really need to get a Haynes. They even have the electrical systems break-down for you plus little pictures of what the connectors look like and approximate locations of them on the car.

Keep in mind that on the '84-85, the fuel pump will not run with the key on and the car off. The fuel pump on those years doesn't start humming until you're actually cranking it over, and then it's supposed to keep running after the car starts, of course. :) This is different from all the other SA's and FB's, which should run the pump with the ignition on.

Methinks you're on the right track though, you could always try to find a way to safely put 12v straight to the pump for troubleshooting purposes. That would tell you whether it's the pump itself, wiring along the way, or clogged carb screens.

Definitley get a Haynes! $14 well spent, and it has a pretty thorough walk-through of the carb rebuild if you make him do it. :)

Armen

I haven't found the specific Haynes manual for that car yet, but I found one that covers all Mazda models for that year, including the RX-7. Not ideal, but I needed something immediately. I'm gonna be looking for the Haynes this weekend...

Thanks for the suggestion!

peejay :
On my '84 13B the fuel pump can be cut by disconnecting the primary of the trailing coil, as you mentioned. (Same effect as a dead igniter, and useful for unflooding and compression tests). According to the FSM, that is not the case for the 12A: they specifically mention that disconnecting the trailing primary wire does not stop the fuel pump. So I assumed the fuel pump activates with the ignition key "on", not just in "start" for 12A's.

Are you maybe referring to a different model year (other than '84/'85)
I'm just curious as to what I'm missing about the 12A's pump... :)

Good Luck kspaight. "I'll make my son rebuild that turkey!" Sounds like a good signature, if you want one. :)

-John.

Hi. I've been working on a 1980-81 for a couple of years. Put in a working 12A engine, did a couple of other things, and at least got it driveable. I was out for a joyride and stopped to fill it up with gas, and it wouldn't start back up again. I towed it home, and discovered that it wasn't getting any fuel. Further investigation showed that the fuel pump wasn't engaging at all. I replaced it (stupidly), and still have the same problem. Obviously, it isn't getting any power. I checked all the fuses in the under-dash fuse box, and didn't find anything wrong. The wiring diagram seems to show a connection to the ignition coil, but I don't know enough about those to make any conclusions. Could it be a bad coil? How do I test them? This is driving me nuts!

Okay, folks - I'm baaaack...

Well, I got it running, but it took a little, um, rigging...

I called Mazda to get a price on the igniter, and was quoted $340. Needless to say, that wasn't an option. I found a salvage yard here who had two of 'em, so I latched onto them for $15 each. Installed them, and it made no difference at all. Still no fuel to the carb.

In desperation, I decided to run a new pair of wires to the fuel pump. I unpugged the pump behind the driver's seat, and connected a wire from the power window fuse connection to the positive side of the pump plug, and a ground wire to the negative. I said a quick prayer, and turned the key. The engine immediately roared to life, then settled down to a smooth idle. I collected my tools, then drove it around town for almost an hour. It's been over 24 hours since I turned it over to Matt, and he hasn't been stranded yet.

Okay, now back to you wizards:
What trouble am I risking by bypassing the standard wiring to the fuel pump? I'm a little uneasy about "customizing" the wiring on this vehicle, but I HAD to get the car running...

Thanks for all your support and suggestions!

Kevin

My '85 will disagree with that! :) Like I said, the trailing ignitor was dead causing the tach and fuel pump to not work. Replacing the ignitor cured that.

Kevin, are you sure the NEW one is good? :)

Thanks, that's interesting. I did think you and Mr Project were referring to 12A's; I wanted to double check. I'm just surprised the factory manual got that wrong.

Kevin: The engine will run on just the leading plugs. So it could start when you add gas to the carb even if the trailing plugs are not firing (and preventing the pump from running.)

With the original pump wiring, you could check for spark on one of the trailing plug wires to narrow it down: if you don't have any, it's an ignition problem.

If you do have spark, I would think it's a bad connection between the coil and ECU, not the ECU itself. If you haven't already, I would remove the primary wires on the trailing coil and clean the connections. Between that and the ECU is a 5 pin connector just below the brake master cylinder. (The coil wire in it should be yellow/green.) It's not likely the connection at the ECU as the tach dies before the engine dies, and it is tapped of the coil wire; for the same reason, it's not likely the fuel pump relay...

I don't know why the pump is wired that way. Maybe it is to prevent us from running with the trailing plugs not firing, which would leave too much unburned fuel to kill the cats?? I dunno.

-John.

John,

Thanks for the detailed info. When I get a chance, I'll use your procedure to narrow it down. Not this weekend, though - I'm leavin' Friday evening and driving to the mountains. Not in the RX-7, though. I've got to get away from that beast!

BTW, my son called yesterday afternoon and informed me that he was stranded on the side of the road with a clutch problem. :mad: Well sure! Why not? It had been running almost 24 hours...turns out that the clutch master cylinder had blown out, so I - we - spent last night replacing that. Come to think of it, it's been 22 hours - my cell phone should be ringing any minute now...;)

Kevin

I KNOW THE PROB... somewhat
 

I had a friend that this happened to, sorry I didn't chat with him more on this now. Deceleration valve, check valve, some little thing the shop charged him $300 to fix. One of the 'normal' things the manual tells you to check for proper operation. I am sure it's in the manual.
I can tell ya he went through some of the same debugging, though not nearly as much as you have.

PM me if this was not enough info, I can give him a call and see if he remembers what was replaced. Hope you get it fixed.