Hello. 1991 740 with 157,000 miles auto sedan Regina system. Just got this car earlier this month. Problem is poor gas mileage : 16mpg local around town and 21mpg highway. I have tryed and checked everything : replaced IAC valve(as idle was too high), replaced engine temp sensor(turned out it was bad so that is why idle was too high), replaced sparkplugs(old ones were ok), replaced air filter(old one was ok), triple checked and no hose,line, or vacuum leaks anywhere, put in a bottle of fuel injector cleaner(didn't make any difference), cleaned throttle(was ok), checked throttle position sensor(was ok), checked oxygen sensor(was ok),etc., etc. Fuel filter is old - looks quite rusted - looks like it has not been changed in a long long time. While idling flow is much stronger on input line then on output side. Is this normal or should flow in & out be about same ? Could fuel filter be reason for poor mileage ? Would replacing it help ? Oh yeah - what is correct replacement part # ? Bosch # 71039 ? Remember I have Regina if that matters. Thanks very much. I really do like this car but will like it much more once I get decent gas mileage out of it.
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' 91 740 sedan nearly 157,000 and ' 87 240DL auto nearly 135,000