Hoping I can find some direction with this. My Civic will start and run for about 4-5 mins then will turn right off. Very frustrating. I’ve replaced main relay/fuel pump. But no change. I can see my A/f ratio is high (lean) any good advice??

 

Do you lose electrical power ? If you installed a factory OEM relay and 100% sure it's good did you check the ignition switch? Does your car have a kill switch or an alarm?

If you don't lose electrical power check your fuel pressure. You can should maintain fuel pressure for a little bit when you shut off the engine.

 

How lean are you running?

Ignition switch or any relay related to that would be my first suspect.

Edit: Just realized this thread is over a month old.