Air-Fuel mixture too rich problem
 

Hi, I would like to ask if somebody could help.
The engine is shutting off due to the air-fuel mixture has been to rich. The car is Mazda 626.

Hoping for your kind response. Thanks.

Need more info. What year and size engine? It will not idle or dies while driving on the highway? How did you determine it was running too rich?

It could be but it depends on what he means when he says it runs so rich it causes it to quit running. It might cause it to die at idle but i would lean toward the MAF or torn intake boot. It being that old it could be tons of things. It might have jumped time or have a bad coil/distributor,plug wires etc. Possibly a restricted exhaust. Pretty much limitless on the possibilities without more info.

Yea 93 was the first year the 626 used a MAF. A torn boot would cause a lean condition but could cause it to die. Not really sure about his symptoms though so throwing out common issues.

Hi guys, yes it's still the same Mazda 626 Auto '93.
Regarding the too-rich observation, this is the what happened.

First symptom is hard starting. So I replaced following:
-throttle body (surplus)
-distributor assembly (surplus)
-spark plugs (brand new)
However, same results were observed.

I replaced then the fuel pump (brand new). After replacing the fuel pump, the car now starts easily and smoothly but after a few minutes (approx. 2-3 min.) you will notice that idle becomes rough until it shuts off. You can then smell the gasoline coming out of the muffler.

I tried to remove the spark plugs and noticed that it is wet with gas.
That is why I mentioned that it is too rich.

By the way, I consulted a mechanic, he said that the problem is the computer box. What do you think?

Hope this provides key information.

Thanks.

Hi, engine size is 2.0. Thanks.

Hi again, may I kindly ask what is MAF and O2 sensor? I am not familiar with these.
Thanks.