1998 Volvo V70 2.0 petrol rev indicator shows about 1500 revolutions when ignition is on, petrol pump is running constantly. When I start the engine it runs unclean, when giving gas it goes out. At the petrol pump 12v volts are on however these are controlled by something so that they are there sometimes, sometimes not. I install 12v directly from the battery the car runs! Fuel pump relays and valve of the return line are already renewed. Whether the spinning of the rev indicator is related to the engine problem I do not know, at least both occurred simultaneously.