Can someone tell me if a bad oxygen sensor is a likely cause for the exhaust having a strong gas smell? If so, which one is likely causing it and is there a way to test before buying a new one? This is on a 1996 Dodge Ram 3.9 with about 126,000 miles on it. I bought it used so I don't know the maintenance history.

(FYI - This truck has a carburetor.)

 

The pre cat o2 sensor(s), but I bet the cat is no good too.

 

... or the cat has been removed. Is there even a cat there anymore. When they are removed it results in a strong gas smell.

 

Are you serious that it has a carb?

 

Is he sure? Rams stopped using carbs in 1986. Anyways a carbed truck wouldnt have O2 sensors and maybe not even a cat.

 

That's not possible. There are no vehicles made in the 1990's (for use in the U.S.) that still had a carb in them.

 

My dad thought for years that the two bbl throttle body was a carb. lol

 

If it still has the converter, yes, a bad O2 could cause a rich condition (which would cause exhaust gas smell). The pre-cat O2 is the only one you need to worry about, all the post-cat O2 (if you have one) does is tell the computer when the converter is bad.

Like others have stated, unless its some kind of custom job, you do not have a carb.

 

If it's running rich and has a cat, FIX IT or don't drive it to much!!! That unburned gas will crack you honeycomb and clog your cat (depending on how rick it is)

 

It's simply a problem with age and machines becoming less efficient over time. I had a 91 Honda Accord and the older it got the more it smelled like gas. I could only tell in the mornings when I started it up in a closed garage. The car still passed emissions testing and ran fine, but it would smell richer as it got older. Sold it a couple of years ago so it doesn't matter anymore. BTW that was a 91, and it was fuel injected.