P0641 GMC - what can i do to make the truck run good cant even get on the gas without turning of

Question

i have gas cap open, signal stability track, service stability track , engine light, engine power reduce and shuts of need help friend checked he got code p0641 and told me it was purge valve when i removed it sand came out of it

Answer 1

P0641  5 volts refence circuit 2

You lost the 5 volt reference circuit 2 without this 5 volt refence you have no acceleration, You will need to measure for 5 volts at the APP pedal, its the WHT/BLK wire if there is no 5 volts you will need to search for a open this can be at the terminal,which they do get corrosion which you will need to clean, Is there is no 5 volt reference circuit 2 at the ECM. you will need a ECM, The cas cap being off will only set off a EVAP code ,EVAP codes dont reduce engine   power at all.