91 b22OO efi seems to run rich oil has slight gas smell?

Wondering what might be the issue here? If its an adjustment, a part that needs to be replaced? How to diagnose? 220,000 miles does have the morning blue smoke if left to sit for a day or two. Runs really good and I clocked just under 24 mpg with probably 30% in town 70% highway driving. Any input greatly appreciated!

Running rich may be the O2 sensor.

OK if it is a o2 sensor shouldn't it throw the check engine light on and a trouble code? No check engine light on and the truck passed Ca. emission about three weeks ago. Starting to wonder if the seller did not do some monkey business to get the smog? Guess I will take it to someone with a sniffer and see the results. At least the current smog is good through Oct. 2015. BUT I would like this truck to be running correctly! Thanks again for any input.

Your 91 probably wouldn't throw an engine light on, because OBDII wasn't on anything prior to '96. I would do an oil change to get the diluted oil out of the crankcase, and replace the O2 sensor, because you get better performance when they are less than 60k miles old.

Your mileage at 24 is not as good as a fuel injected B could be. That is what the carbed units when they are working will do.

You'd be surprised what "sins" can be resolved by a new O2 sensor. They are cheap, relatively, to other options/issues and fairly easy to install.

Check for leaking injectors.