Volvo Repair: Volvo 240 rough idle, running rich, volvo 240 dl, chevron techron

Question
Hi Chris,
    I have another mass airflow sensor that is brand new. I put it in last night, and the same problem persists. Where is the fuel pressure regulator located and how can I test it. By the way I forgot to tell you the oxygen sensor is about 5,000 miles old.

Thanks for your GREAT help.
Lewis
-------------------------
Followup To
Question -
Hello,
   I have a 1987 Volvo 240 DL wagon with 147,000 miles on it. The car has always gotten 26-28 mpg on the highway. The car all of a sudden is idleing very rough, almost stalling and the gas milage has dropped to 24 mpg. Also when it starts, it first puts out greay smoke and does not start as easily as normal. The catylitic converter has 7,000 miles on it. The plugs have been checked , cleaned and gapped. Plug wires are 3 months old. The air filter is new and I use Chevron Techron 1 every 6 months.
   Your thoughts would be appreciated.

Thanks,
Lewis
Answer -
possibly the mass air flow sensor, or the fuel pressure regulator is failing or has failed.

Answer
fuel pressure regulator is located by the oil filler cap. on a metal tube right about ontop of the distributor cap.  its a 1 1/2 inch diameter metal can. it has 2 bolts holding it in, and a vacuum line to the front of it. if there is any type of fuel at all in the vacuum line then the diaphram has failed, and the regulator needs to be replaced. on the vacuum side there should be NO liquid. just air (vacuum)