My 88 convertible cold starts normally and runs well but after it gets to normal temp either starts hard like it is choking out or won't start at all until it cools down.

It was just in to have all vacuum lines tested and replaced, new plugs and plug wires, new belts and cleaned the electrical connection going to the injector.

The car has 90k miles on it, what could be the cause of this.

 

..a lot of things can cteate HOt start,
Somtimes it could be low compresion,or leaky fuel injectors allowing Gas to Sneak past the injector and into the engine after shut down,This is beacuse the Injectors are still under pressure until the Gas can return to the Tank,via the return line.,
Injectors can be taken off,cleaned and replaced,,,the Quick Fix if Injector Cleaner is a waste of money.it is Do it right or Nothing.
Another HOt Start scenario can be Because of a Bad Temp sender at the Water pump..it is located on the Water pump housing and is hidden by the alternator(green connector is attcahed to that sender)
If the Sender is not connected or is Bad,it will make the ECU think that the car is Still COLD and Give it Too much fuel on Retsart,.,The Outcome of that is a HOT-START.(flooding)
It can be replaced easily.(sometimes it works,sometimes..IF ir is indeed the problem)
HOT starts are Remedied by Cuttiing fuel to the Injectors,to Clear fuel out of the engine.
That is done By Removing the EGI FUSE( located on the Fuse block in the engine bay),Roll the engine over with the Fuse OUT to Expel the excess fuel,( about 8 seconds).Replace the Fuse and Restart.,..A total pain in teh *** but it works.
YOu could always Look up on HOW TO put a Fuel KILL switch on it,so when this happens you do not have to go through the Process.
Myself,I am going to put in the switch inline with the EGI fuse so that I can hit the switch and cut fuel fron there.
another method is to Pull the fuel pump realy under the dash,ad replace and restart.But I don't like the idea of having to Put back a Relay that has six Connections on the Connector.Something may go wrong(bend a tab on or IN the connector and the acr will not start.
so,all in all,I hope that gives you a Little insight into your problem.
HOt starts are one of the Things that RX owners go through,often.
Proper maintenance can make it go away..and maintenance is Key with an RX7.They love attention..so love it and it will love you back.Cheers STYX.

 

Thank you for taking the time to answer my very broad question. I will attempt these fixes over the next week and let you know which one effected the problem.

Aloha and I hope the climate is warming in the great white north.

 

Im experiencing the same issue, powerful 93' feels amazing running, can't quite put my finger on the issue but the car is running pig rich and hot restarts are a problem. Sounds to me like somethings up with my temp sender by what's written above, or possibly injectors stuck open and flooding the engine insanely. I can smell the gas from the exhaust and the car is fouling spark plugs within a month every time i replace them... i'll look into all this too! btw how do I know if my temp sender is completely screwed up? voltimeter?

 

I'd service the injectors.(it wouldn't hurt to clean them anyways IF that is NOT the problem.)
I've had the 3 minute Run then NO start problem too.As a matter of Fact it is going on with my 750's.
I hooked up a "kill switch" to alleviate that problem,as I don't want to Screw with the injection system until I switch to bigger Injectors(I am running Turbo,RTEK,and FMIC,,and so on.)This Switch will just diasable fuel and clear the Engine of excessive fuel.Then when you Hit it again the fuel system is back ON and the car starts right up.
The POWER Question: really Leaky Injectors will not show up as Power loss or Power gain..It has nothing to do with it..When they Leak,it is Usually After the engine is OFF.and the Fuel takes the Easy way out,rather than go back to the tank Via the return line,it will just **** out the leaky injector.That is why you get the NO Start,or Hot Start problem.