Had a sudden intermittent change on the M.P.G. display on a fuel injected car engine. After A LOT of investigation,the fault turned out to be a very small leak on the pick up/inlet side of the fuel system. This was letting a very small amount of air in,which ' dashed' through the fuel flow meter,showing extra flow ,i.e. less miles per gallon. However,this small amount of air was,presumably absorbed into the fuel at the high pressure of the injection system,as the running of the engine was not affected. This was a t..t to find. Hopes this helps. (The leak was found to be a' scratch' on a copper washer in a connector.This was on 500 hp rally car engine!)
