What is open and closed loop fuel system?

Question

What is open and closed loop fuel system?

Answer 1

Closed-Fuel injection. Unused fuel is fed back to the tank.

Open-carburetters, unused fuel is wasted.

Answer 2

A closed loop system is one that controls it,s output by monitoring its output. Such as receiving information from sensors and the E C U making the necessary adjustments as required.An open loop system does not control it,s output by monitoring it,s output which was the way before computers were introduced into cars

Answer 3

All 1996 and newer cars are OBD II (On Board Diagnostics Two) and go through open loop before the oxygen sensors warm up.  This is when the vehicles computers do not use the vehicles sensors to run the car, but runs the car through programmed defaults.  In closed loop the computer takes information in from the MAF(Mass Air Flow) sensor, Oxygen sensors, knock sensors, intake air temp sensors etc.... to get the information it needs to run clean and efficient.  The reason you have open loop is the oxygen sensors won't work until they are at least 600 degrees farenhiet,  therefore it has to run on programmed settings until they warm up.