Have you twisted an ignition wire boot off any of the spark plugs, stuck a factory recommended new plug in the boot, grounded the threads on the motor and has someone spin the starter motor to see if you had any spark?
You can remove the O2 sensor from the exhaust and try to start it, if it starts it could be the cat or a defective crushed exhaust pipe (internal dual wall pipe, the inside wall collapses and blocks the flow of exhaust gasses) or put a vacuum gauge and watch it while cranking it over, it there is a blockage the gauge will fist show a vacuum than it will return to zero. Good Luck!
If the cat converter was bad enough to prevent starting, it wouldn't be intermittent. Get back to the basics; check for spark while cranking, check fuel pressure, check to see if the fuel injector is firing.
Anyone that thinks a cat converter will keep the motor from starting should close the hood and get a mechanic! You are not even close to understanding how a motor works and are dangerous under the hood!
Cat converts don't go bad for a while and then go good so look somewhere else.
Check for a lose venturi just inside the carburetor.Tighten it up if loose.
There is no reason to suspect the cat anymore than loads of other components
Have u checked the distributor cap? Could have oil
I have a Honda civic 91 and its a 4th gen sedan. The problem with it is that the engine cranks but it won't start. I checked the spark plugs and they are all good. Battery has been recently replaced. What i don't get is why it starts up at times and doesn't. Could it be by any chance the catalytic converter that's ruined?
