Volvo Repair: high fuel consuming problems, coolant temperature sensor, fuel pressure regulator

Question
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Followup To
Question -
my car is volvo 940glt model 1992 with a 16-valve DOHC engine (B234F) with a gulf model which is come without CO sensor (lamabada sond) and without catalizer , its recently consumed too much fuel and the CO is around 6,7 which is too high , what are the all possible things that may cause high CO outlet and high fuel consuming ? and if the exhust is damaged do it effect the CO gas outlet from the engine ?

Answer
yes the exhaust can affect it if there is a leak before the O2 sensor.there are many things that can affect the CO. any fuel sensor in the fuel system can cause this.engine coolant temperature sensor,air mass meter,fuel control unit,throttle switch,injectors,fuel pressure regulator,O2 sensor.