I’m having a weird issue with my 1998 Fort ZX2. The car is very hard to start when cold and it runs extremely rough, but only through my first acceleration under load. In other words, I can rev the engine a few times while in neutral, and it will run very rough, and once I start driving, it runs really rough through my first acceleration, but then it smooths out and runs fine from then on until I stop it and let it call off for 30 minutes or more. If I restart it within 30 minutes or so, everything is fine, but any longer that that and the problem reappears. Anyone have any thoughts on this?
I had a similar problem with a 1981 Nissan Maxima. It might be the fuel pump. It takes to long to build pressure in the fuel lines. Perhaps when the engine is off, the pump leaks it fuel back into the gas tank causing the pressure in the fuel line to go down.
The problem might be with the anti drain-back valve on the fuel pump.
To check for this, the next time you go to start the engine, turn the ignition switch on so the dash lights come on for two seconds and then turn the ignition switch off. Repeat this a half dozen times and then try starting the engine. If the engine starts and runs smoothly the problem is with the anti drain-back valve on the fuel pump.
Agree with the ideas above, most likely some kind of fuel pressure problem. Besides the fuel pump check valve, could be a leaky injector too.