[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]

My fuel pump story

     When I came home last night, my wife informed me that her '90 100 
     would not start.  When I tried to start it, I noticed that the fuel 
     pump was not priming at ignition on time.
     I then went ahead with the diagnostic procedure outlined in Bentley, 
     using #52 terminal on the relay panel (fuse box), where the fuel pump 
     relay normally resides.  When I introduced 12 volts (from the battery) 
     to the terminal, 12v was present at the fuel pump connector.  I then 
     reconnected the fuel pump and tried the same experiment.  The fuel 
     pump would not work.  It made a knocking sound when I connected it to 
     the battery.  After several more attempts, I reinstalled the fuel pump 
     relay.  Then got into the car and turned the ignition on and of 
     several times just to make sure I was not imagining things, and 
     interestingly on the second try, the fuel pump started working.
     This morning, I decided to repeat the test procedure, and sure enough, 
     when I connected it to the battery, it hummed along with no problems.
     Not too long before this failure, I was noticing that the pump 
     generated some knocking noise for a short time after cold start (about 
     5 knocks approx. 1/2 sec apart).  Past that, the pump worked without 
     the "buzz", and without irregular noises typically observed.
     It felt like the pump hit a "dead" spot, and by introducing spikes of 
     voltage it made it past the dead spot.  I suspect that the fuel pump 
     needs to be replaced as soon as possible.
     Can anyone recommend a good source for a Bosch pump?
     Hope this info can be helpful to some of you.