Hey grey ghost if its the same as my 82 b21 its under the intake manifold. There is a little hose that connects to the intake manifold right in the center, if you follow that little hose you will find it. Like I said this hinges on if the motor is set up the same way, You can also remove the idle air control valve(big thing on the intake manifold probably gold with two big hoses on either side) if you pull that off you can see the flame trap better. It is comprised of a small hose that goes to the intake manifold and a large hose that runs down below the throttle body, the flame trap itself is a little plastic cup with holes in it(kinda like a smashed thimble) and it sits inside the part that goes into the block. If any of these become plugged(and they do)it can cause backfires and if your lucky like me it will only blow the flame trap apart and not blow out your engine seals, it creates an vacuum leak but compared to the time and money to replace the seals its an easy fix. Look under the 700/900 FAQ on this site and it will give you detailed info on replacing it, its a pretty easy job but if you have giant hands it could be a bit difficult:). Parts are cheap and you can probably get everything you need from the stealership or off of FCPGROTON.com, good luck.