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Temporary almost complete loss of power today

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    Temporary almost complete loss of power today

    So first let me set this up for you. I drive an 89 Auto 325i(soon to be manual). I was in traffic for about an hour today, i had just gotten out of traffic and was switching lanes etc and going to accelerate from about 50mph to 65 or so to get to normal highway speed, but when i pressed the gas pedal nothing happened at all. Engine didnt rev, nothing. But it continued to idle/run fine with no hiccups, sputters, etc. So i changed lanes and exited since i would soon use up my coasting speed and be stranded.
    When i was coasting down the exit ramp i found a sweet spot, where by barely (and i mean barely) pressing the gas pedal i would get some acceleration(again with no sputtering). After a few moments of coasting on the feeder i was able to accelerate normally throughout the range of the pedal and made it to a gas station. I noticed the gas light had come on, so i thought maybe i ran the tank almost dry. It filled up to its normal 12.9 gallons, so i didnt run it any lower than i normally do.

    here are some figures of my latest MPG/ fillups that i could find in my glovebox(i know these figures can sometimes help with troubleshooting), and relavent work.

    date trip odometer amount filled up mpg
    7/7/2012 302 12.9g 23.4
    8/3/2012 320 12.9g 24.7
    9/1/2012 295.5 14.25g 20.7
    9/21/2012 262 14.3g 18.3
    10/4/2012 209.9 12.9g 16.18


    I fill up almost as soon as the gas light comes on, but the guage usually has is in the red for a little bit before the gas light comes on. I base my mpg calculations on how much i put in the tank, since technically that should be the amount i used. I write it on the receipts after i fill up so i can try and keep track of any problems. As you can see this time, i only got 209 miles before the gas light came on, which is a bit less than normal. There are a few receipts missing, but i typically have been getting 260ish miles to a tank lately with around 17ish mpg.

    I replaced the fuel filter on 3/4/2012 and it has about 2000 miles on it. Im pretty sure(tested it with multimeter) that my TPS is bad, and also my gas tank has a decent but not huge bend in the bottom of it, which i know could decrease the volume of the tank.

    So with the information i have provided, here are my questions:

    Any reason why my typical fill up is almost always 12.9 gallons before the pump stops?(like could there be something that only is allowing that much in)

    Any reason for the almost complete loss of power today?

    I do have spark plugs, cap and rotor, and oxygen sensor sitting in the garage ready to be installed as well. But all the parts on the car currently(other than oxygen sensor, pretty sure thats bad) seem to be working correctly to my knowledge other than just being worn/tired.
    89 325i Coupe Auto Delphin Metallic - Sold
    91 325i Sedan Auto Brilliantrot - Sold
    83 323i Euro Coupe Manual Lapisblue - Sold
    89 325i Coupe Manual Delphin - Sold
    89 325i Sedan Auto Brilliantrot
    87 325i Vert Manual Brilliantrot

    #2
    Oh and currently the other issue i have is high idle when not in gear, like around 1800-2k, which i believe i have traced down to being the TPS. Not sure if that will be useful info for this issue.
    89 325i Coupe Auto Delphin Metallic - Sold
    91 325i Sedan Auto Brilliantrot - Sold
    83 323i Euro Coupe Manual Lapisblue - Sold
    89 325i Coupe Manual Delphin - Sold
    89 325i Sedan Auto Brilliantrot
    87 325i Vert Manual Brilliantrot

    Comment


      #3
      It isn't a good idea to routinely run the tank down below 1/4 tank. The fuel pump is cooled by immersion in gas and running the tank down to the point that low fuel light comes on has the pump dry. At that point there is 3-4 gallons of fuel left in the tank. Your tank holds 16.6 gallons, so filling the tank with 12-13 gallons when the warning light is on sounds about right.

      The description of the power loss sounds like a fuel delivery problem. Since it occurred with low fuel, the pump may have been starving. If it does it again, see what the econometer is showing. If there is a fuel delivery problem the econometer will drive to zero.
      The car makes it possible, but the driver makes it happen.
      Jim Levie, Huntsville, AL

      Comment


        #4
        I don't get the point of driving the car until there is practically fume left in the tank. The gas consumption is independent of how much fuel is left inside the tank so why run the risk of overheating your pump...to gain what? Back to your post, it is most likely that your pump was sucking air at that time. 3 or 4 gal in the tank is not much and a simple lane change can shift the fuel away from the pump inlet. Your idle speed of @ 2K is not a good sign. I would check for vacuum leaks immediately.

        Comment


          #5
          Yea i know about the pump overheating thing, but i dont run it down to fumes. I fill it up as soon as the light comes on. I wouldnt think bmw would design the light to come on at a time when it is potentially harmful for the pump. Yea im starting to think it just might have sucked dry, i may have been on an incline on the highway or something. Although it has never done that before, but i guess i have never driven it on an incline with the light on. And yea i just got every piece of hose(coolant and vacuum) under the hood in the mail the other day, and have narrowed the idle issue down to the TPS, so idle will be fixed soon.
          89 325i Coupe Auto Delphin Metallic - Sold
          91 325i Sedan Auto Brilliantrot - Sold
          83 323i Euro Coupe Manual Lapisblue - Sold
          89 325i Coupe Manual Delphin - Sold
          89 325i Sedan Auto Brilliantrot
          87 325i Vert Manual Brilliantrot

          Comment


            #6
            The light is there for folks that don't check their gauges (i.e. an "idiot light"). The light is basically saying, "Hey stupid, you are about to run out of gas!".
            The car makes it possible, but the driver makes it happen.
            Jim Levie, Huntsville, AL

            Comment


              #7
              Sounds like fuel starvation for sure. Happened to me the other day on the track. Granted, I was taking wide sweeping right handers at 70+mph, but it's the same physics.

              Comment

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