Fuel Filter Replacement

[jsean]

My 1989 525i just began running very poorly with no advance notice. In fact, it is no longer driveable due to the inconsistent ideling and acceleration. When I press the gas, it basically pulsates and lunges the car back and forth. I replaced the fuel pump fuse, and this seemed to have helped, but I'm wondering if the fuel filter also needs to be replaced. However, I'm not sure where it's located. Is this is a fairly simple job? Should I be looking at the fuel pump too? Again, the car seems to be running fine, but I'm concerned something else may be wrong.

Thanks!

[jeffreyb4me]

the fuel filter's just above & behind the R/R axle shaft but this doesn't sound like your problem & failing fuel pumps USUALLY won't even allow it to start. the sudden unset sounds like an intake air leak [cracked or displaced air hose]. i'm going to have a look at your other posts............

[jsean]

I actually replaced a split intake hose a week ago, and everything seemed fine. I will check the other hoses. Right now, the car is running okay... but it does idle a little rough. I'm wondering if the fuel pump fuse replacement relieved enough pressure to clear the fuel filter. Is this possible? Thanks for your feedback!

[jeffreyb4me]

no...the pump fuse issue sounds irrelavent, keep looking. jb

[Aladdin]

Another good place to look would be to pull the spark plugs in your car and see if they give you any signs as to whether the fuel mix is rich or lean. If they do give you any sign, I'd look next at your O2 sensor and think about replacing it. (I saw on your other post that your check engine light is on and in my model, 1990 535i, the manual says that light is emissions related.) Diagnosing an O2 sensor is beyond my capability though. I pulled my plugs and they looked as if the car was running very rich so long story short, after ruling out all else, I took a plunge and changed out the O2 sensor.

[jsean]

Thanks for the insights. I'm still noticing short gasps for air/fuel while driving at lower speeds and the idle is pretty rough. I now have several things to check -- air intake hoses, O2 sensor, air filter... as well as possibly the fuel filter and plugs. Based on the feedback thus far, it appears to be more of an air flow issue than a fuel issue. By the way, what does the O2 sensor cost? If this is an easy fix, perhaps I should replace it anyway. Thanks again, JB and Aladdin!

[jeffreyb4me]

the O2 sensors do fail and on earlier DME's like yours, when they short can sometimes drive the DME far to lean or rich. not REAL hard to replace.