'89 NA RX7 will crank with no start
 

I have a '89 GTU with the last time it was running being 15-20 years ago. I am unable to identify what is wrong with the car. It will crank but will not start. Cranking seems to be faster than normal and the car will start to shake after 8-10 seconds of continuous cranking. Here is a list of things I know to work or have replaced:

replaced fuel pump
replaced fuel filter
replaced circuit opening relay
replaced ignition switch
got starter checked
spark is good
not mechanical or electronic but got new rear hatch struts and ofc windshield wipers
ecu works (needle on tachometer twitches when cranking and every other thing in the car works just not the engine)

the only thing i could think could be the problem would be the AFM or the fuel injectors

Any help would be appreciated. Thanks <3

silly question, but did you replace the fuel in the tank as well? does the exhaust smell like fuel when cranking?

The tachometer does not get it's signal from the ECU, so I don't think it's safe to say that the ECu couldn't potentially be a problem. That said, I think it's pretty unusual for the ECU to go bad on these cars.

Also, i don't believe the MAF is used on starting. you should be able to disconnect the MAF and it'll still start....won't stay running, but should still start.

I did not change the fuel after installing the new pump. the fuel is new though
the exhaust somewhat smells like gas and there is a gas smell when cranking. there is a thin grey/white smoke that barely comes out of the left exhaust though
I will certainly try the trick with the AFM so thank you for letting me know about that
I am not sure why I have associated the tachometer to have something to do with the ECU but its good to know that it is not too often they go bad

I'd start with the basics.

Make sure you have spark by pulling spark plug out and visually verify spark (sounds like you did)

Make sure you have fuel. Start by pulling the fuel supply line and crank it, you should see fuel coming out the line. If you do, make sure your injectors are working. Best way is to take the primary injectors out, secure them to the rail and visually verify both injectors are spraying during crank.

If you have fuel and spark, the only thing left is compression. Test that next.

that is something i forgot to mention. compression is 90 in rotor 1 and 110 in rotor 2. Thanks for the help!

did you make sure there are even pulses on all 3 faces on each rotor? Those numbers are meaningless if the pulses aren’t even, could still mean no compression in 1 or 2 chambers.

I just ask because if the engine sat that long, seals can be stuck.

check if the timing is set properly under the cap of the crank angle sensor.

if the engine floods, you can deflooding it by fully depressing the gas pedal. But the spark plugs may be soaked in fuel and need new ones while the old ones dry out.

Update: I unplugged the AFM and attempted to start the engine on starter fluid with no start but smoke coming from the exhaust. I decided to take another compression test and after taking the bottom plugs out I noticed that neither really smelt like gas and only the plug in rotor 1 had oil on it. It then started to rain so it is a perfect time to do some more digging before I move on

If the engine has compression your fuel system is probably full or trash. Remove the bulkhead cover in the hatch, pull off the return line and extend it into a bucket outside the car. Run the pump until you see clean fuel and then turn it off and dispose of the fuel with used oil. After that remove your fuel rails and have the injectors cleaned and flow tested by injector-rehab or a different vendor. They should come back with new o-rings, pintle caps, and grommets and be ready to run. Be sure to get a new LIM to UIM gasket to install during reassembly and replace any cracked or brittle vacuum hoses.

It's a good idea to flush the coolant and replace the thermostat with an OEM stat right after you get the car running. Be aware you may experience a coolant seal or water jacket seal groove failure due to the car sitting unused for so long, it may run and drive fine for a while though.

If the car immediately goes into limp mode your electronic oil metering pump has probably failed- if that is the case search about it to figure out what steps you want to take.

+1 on the fueling issue.

Make sure your injectors are getting voltage, or are the correct impedance for your year. I believe the 89's were high impedance.

Check your FPR and make sure it's not busted. Follow the procedure in the FSM.