I have noticed a momentary but complete loss of power when the tank is in the red or after extended hard excelleration. The code 121 shows up at port 2, port 6 is 111(OK). Could this be: 1)Plugged fuel filter. 2)Failing in-tank pump. 3)Air mass meter. The car has 146,000 miles, a recent tune-up with OEM parts and runs fine in all other aspects. It never stalls, the check engine light does not come on, it just feels like I have run out of gas. Today it happened with a full tank.
Thanks in advance,
Steve M.

A fault code of 121 is for the AMM. I got that code the other day, and my car was losing power intermittantly, it ended up being a dirty terminal on the AMM, I guess I was lucky. If your car runs fine reset the code and see if it appears again.
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My 91 245

Good call Andrew! After reading your post, I went out to check the connector and sure enough, I have green powery corrosion on both the plug and receptical. Now comes the question of what to use to clean it out without damaging the connector any more that it is already. That is if it is not already too corroded to salvage. The wiring harness side of this equation is in petty sorry shape. Any suggestions?
After 27 years of owning Volvo's most of my demons have been electrical in nature.
Thanks,
Steve M.

Steve,

You need a spray can of electrical contact cleaner and a small brass bristle brush (toothbrush size). Disconnect the battery first, then spray and brush any contactsthat need cleaning.

Contact cleaner can be purchased at Radio Shack, they call it TV Tuner Cleaner. The RS brand is OK, but Caig De-Oxit 5 is the best - it cleans/deoxidizes and leaves a protective film. Caig chemicals are available from electronics specialty shops. Radio Shack can special order it for you, or you can order it at radioshack.com.

I agree about the electrical demons. They can be a pain to debug, but the fix is usually cheap once the problem is found.

-Ron