RX7 questions

So, I've created a monster - my son is looking at a project car, 85 RX7 that runs until it reaches op temp, then dies.

Assuming he comes up with enough cash (dear old dad is going half's with him... yes, I'm an enabler) and we pick this thing up, common problem?

As an 85 I assume injected, and that sounds like a temp sensor of some sort, cold start valve, etc...

Know nothing about the cars though, so what else should we be looking for as we go check it out?

It'll only be fuel injected if its a gsl-se with the 13b otherwise its a 12a with a carb.

Look for rust under the rear storage bins. You can remove them with a Phillips screwdriver.

If its not an injected car it has a manual choke that is closed by a magnet when the engine reaches operating temperature. It may not be closing or it may be closing prematurely Can sometimes be an issue. Biggest single issue I've had was around electrical system not being grounded. Worth making sure that grounding sites are clean and secure.

Watch the tach. There are two ignition systems, leading and trailing. The trailing is there for maybe 10% more power and much better emissions, but the engine can run just fine on the leading alone. Mazda put the tach lead on the trailing ignition for this reason. The engine computer (the carb models have one too) gets its signal from this same wire. If the trailing ignition dies, usually from a bad ignitor which fails hot and is tucked up on the distributor next to the alternator, the tach will stop working and a short while later the engine will quit because the ECU shut off the fuel pump.

The strange thing is, the fuel pump relay is a NC relay. The computer has to energize the relay to shut off the fuel pump. So a quick (ha!) workaround is to pull the passenger side carpet up, remove the floor plate to access the computer, and unplug it. Not recommended to do this if the engine still has a catalyst on it and the solenoid rack, since the purpose of the solenoid rack and air pump is more or less to keep the cat from slagging. Well, cats. An '85 should have three of them.

Do it.

Some good info here: http://www.rx7club.com/1st-generation-specific-1979-1985-18/1st-gen-rx-7-faq-page-237777/

excellent, thanks fellas. We'll check it out in the next day here, I think. I've been playing painter all day today. Looking at and working on old cars is more fun.

the son just created an account and is checking in. ive texted the guy and will see him sometime tomorrow after school as ill be down there anyways. anyway to test the magnet or that wire thing without fixing it on accident? (trying to keep the price down haha) also a link/pic to where those are located would be nice. if not i can google during class when we are doing nothing.

anyways its midnight thanks for all the help!

The thermo sensor that keeps the choke knob electromagnet active is located in the thermostat housing or more accurately the back side of the water pump housing which is also where the thermostat lives. Look on the passengers side of the car between the carb, and water pump and you should see the sensor. Maybe two wires on it. It is hard to see between the rats nest of vacuum,oil injection, and wires, but it's in there.

Your problem could also be vacuum leak related. I had a similar problem years ago where the car wouldn't idle, but did run on the choke, or if you kept your foot in it. Turned out one of the many vacuum caos I installed was split, and I had a major vacuum leak. One new cap later and I wa son my way. I found this while removing the engine for replacement. If you get it remove the rats nest of vacuum hoses ASAP, and you will be mucho happier.

Good luck, let us know what you end up doing. I have owned a few RX-7's over the years and still have my 78 GS. I love these cars!!

Chris

I had an '82 12A GS that did the same thing, it had idle passages clogged in the carburetor base plate. Damned if I know what they were clogged with, I finally had to get a base plate from another carb. Ran great after that, loved that car. Only sold it because baby.