Fuel System Problems

[alabamaalfa]

Looking for some assistance diagnosing what I beleive is a fuel system problem. I have 1984 Alfa Spider Veloce. I have just replaced the cat converter and O2 sensor. I am running a K&N cone air filter that replaced the original air box. Fuel pump (main) and filter are new. Tank strainer is clean. I have difficulty starting the car, hot or cold. Going down the road under load the car sometimes stumbles and stalls. Idle starts smooth then stumbles then smooths out again. I am in the process of checking all the hoses, clamps, etc and suspect that air leaks are the problem. Before I replaced the cat converter and sensor, this was not a problem. Related? Looking for some extra insight....

David

[slyalfa]

have you looked at the plugs?
if the O² is bad and is making it run very rich you might be cloging up a spark plug and that would make it hard to start. But the air leaks are the most common just them working on it they might have pulled somthing off.

[RayKiszely]

I have an '84 and it has Bosch Fuel Injection. I assume that you do too. My car is stock and I was cleaning up and repainting the air cleaner box. After I reinstalled it I started up and it ran like yours is described. Then upon closer examination I discovered that i forgot to re plug in the connector for the Box. I have no Idea what it does, (my guess is that it regulated the flow of air to the system) So when I plugged it back in it worked great, just like before. Hope this helps. Maybe someone else will reply and tell me what the heck that plug does.
Ray Kiszely

[rmatteo]

Sounds like an air leak. Check all your vacuum hoses for leaks, and pay particular attention to the large intake hose that runs across the top of the cam cover. Also make sure you have a good connection at the cone filter.

[alabamaalfa]

Thanks for all the advice. I ran down all the hoses and no leaks. Decided to check the new O2 sensor and guess what! It was bad. Amazing what a bad sensor will cause. Thanks again....

David