My 1987 Volvo with 285,000 miles is running rich and naturally lacking some power and mileage is down. It used to get 26-28 mpg highway and dropped to around 23 highway over the years. This past winter it started getting only 16 to 17 mpg and I noted it was was sluggish accelerating. I also note a black sooty tailpipe. I do not see any smoke. I did a number of checks: Spark,HV wires,timing, valves, compression,and air intake. Then I tried pulling electric connectors appart and reconnecting several times to try and reestablish a good connection on a tip from a friend. Even though it is spring and warmer now, this condition has remained consistant.

I have read the FAC on Running Rich.

1. I don't appear to have a high fuel pressure (although I do not have a meter to test it) since I do not have a start problem, and the problem remains hot or cold.

2. Based upon the fact that I am not getting any gas in my oil, it would seem that my injectors are closing, although I guess it may be they are not closing 100%.

3. No mechanic has been around my engine to adjust my AMM to compensate for a sticking fuel check valve on the front of the fuel pump.

There are some other suggestions in the FAC, but I am now thinking that since the AMM is adjustable, perhaps I should try this. However, I do not know where to find it and I do not know how to adjust it.

I would appreciate help in this area. Or if know of something else I should check first I would also appreciate that.