Hello everyone. My car is running rich on fuel. It has no miss fire or hesitation, it is running smooth but on cold start it's running rich on fuel and I can smell the gasoline from exhaust pipe.
So far I have cleaned throttle body and replaced the spark plugs, spark plug wires, ignition rotors, distributor caps and temperature thermostat. It is also burning a lot of fuel than average car. Any ideas?

 

Lots of ideas. First is the check engine light on? Next a normal culprit is the engine coolant temperature sensor, it tells the ECU that the engine is now warm and does not need enrichment, if its bad it tells the ECU the engine is cold all the time and is stuck in cold enrichment mode.
Another thing is the cold start valve can be leaking fuel into the intake all the time. Then there is the O2 sensors that can give out the wrong information and cause similar problems. If (which it is not) it was OBD2 and the check engine light was on that would mean when running it would not be using the O2 sensors to sense the air fuel ratio's and instead using the preprogrammed fuel maps to limp the car to a place of service. High fuel pressure can cause a too rich condition in some circumstances too.

 

No check engine light is on but I believe it is O2 sensors. Thanks for the in-depth information.I really appreciate it.

 

Almost certainly the coolant temp sensor. Mine did the exact same thing.

 

I replaced temperature sensor last year and I also examined ECU and found nothing wrong with it.

 

Just changed the down stream O2 sensors and non of them show any resistance. The multi-meter stays at 0. I wounder if the down stream is suppose to be like this. Now I ordered two upstream OEM sensors hopefully that will fix my problem. Upstream sensors are more expensive than down stream sensors.

 

From what ive read here,just looking at the ECU wont cut it.

 

The O2 sensors should have an ohm reading... no ohm reading could be they are toast.
And if you've not done the ECU repair as indicated in this forum I'd do that. It can cause all sorts of wacky problems that don't seem to relate.
Since it's a known failure point, it just takes that possibility out of the way.