Hi,

Car is running *very* rich and very rough, especially under no load, at any RPM, as if one cylinder is not firing properly and all the others are very very rich. I'd like to pull out the fuel rail and injectors as a unit and check the spray pattern and compare the relative volumes of each injector. My main question is during this process can I use the original "O" ring seals over again? I'll probably buy new ones but if I have to remove something twice will I have to replace the O rings again? Any other caveats? Thanks.

/// Be sure to use either the correct Volvo o-ring or high temp o-rings if you substitute. I haven't replaced the seals on my 83 but I had problems when the wrong o-rings were used on earlier cars. Standard o-rings will harden and shrink to the point of breaking.

"I'd like to pull out the fuel rail and injectors as a unit and check the spray pattern and compare the relative volumes of each injector"

You can't do this safely with electronic fuel injectors but they can be cleaned using a pressurized injector cleaner on the car, engine running by following the instructions on the can. Motorcraft makes a good product for that but a fuel rail adaptor is required.

A bad or partially clogged injector will cause a miss but if it's running rich, I doubt that your injectors are the cause of that.