This is a guild,tell you how to get unlimited fuel and shutdown reaper detection in Mass Effect 3 by Modify Coalesced.bin.

I use this tool ,there are other tools,any way,if you can find the right place.http://blog.gib.me/2012/02/16/mass-effect-3-coalesced-bin-tool/

inbioweapon.json,search "fuelefficiency",change its default value "1.5" to a smaller one,such as 0.015,fuel will be more efficient,then 1000 fuel will be enough for scan the whole galaxy.

"fuelefficiency": [
 "1.50"
],

inbiogame.jsonsearch "m_fscandetectionrange",find this part:

"sfxgamecontent.sfxgalaxymapreaper": {
   "acceleration": [
    "5.0"
   ],
   "m_fscandetectionrange": [
    "300;"
   ],
   "maxspeed": [
    "67.5"
   ]
},
change "300" to "0",then reaper can not detect you,there will be no reaper alert any more.