87 535i Died

[Pearson-Franks Family <pearsonf@xxxxxxxxxxxxxxx>]

Richard:

Lots of things to look for.  From your comments, I gather
it cranks OK, but does not even try to start.  Also, that
you are not out of gas, or something else embarrasing!  ;~)

1)  Power to the People (er, Engine!)

- - With the key on and not cranking, you should hear the tiny
  buzz of the idle control motor.
- - Likewise if you have a multimeter, you should find +12v
  (or so) at both primary terminals of the ignition coil.
- - If no joy on either of the above, suspect the 'main'
  relay (or corroded connections).
- - This is one of the relays clipped to the outside of the
  fusebox, a 5-pronger, the Bosch part number varies from
  time to time.  The Electical Troubleshooting Manual id's
  the relays on an '86 as 'Main', fuel pump and o2 sensor,
  front to rear.  The '87 should be similar.

2)  On to Spark-ness!

- - If there appears to be power, pull the plug wire to the #6 (rear)
  cylinder; the easiest to get to.
- - Insert in a spare spark plug, ground the outside of the plug
  and have somebody crank the motor.
- - You should see a fat spark a couple of times a second.  If not,
  do the same test, but this time with the wire directly from
  the ignition coil.  If this works and wire #6 didn't, pull the
  distributor cap and test the rotor - it may be open, or not
  moving (bad).
- - If _still_ not sparking, leave the ignition on and short pin
  1 (NOT 15) to ground with a hank of wire.  You just imitated
  the action of the ECU thinking all is well with the world, and
  telling the coil to fire.  If it did not spark, suspect the coil
  or the ECU.  You can look for less than an ohm between the two
  primary coil leads, and hundreds or so from the high tension
  lead to ground.  The ECU (above the glove compartment) is a
  'black box' to be swapped, not troubleshot IMHO.
- - Weird note:  if it _did_ spark when grounding pin 1, try starting
  it again.  If it starts, you need a new ECU.  If it doesn't,
  just continue the troubleshooting!
- - If the grounding of pin 1 got a spark, but the car does not
  restart, move on to the TDC and timing sensors.
- - These are the three conductor connectors imbedded in the rear
  intake manifold brace.  One is black, the other grey.  The
  sensor is just a coil wrapped around a magnet, and should
  measure 960 ohms, +/- 10%.  The third lead is a shield, and
  should measure effectively infinity to the other two leads.
  Sometimes these connectors corrode, or are full of water.

3)  Fuel

- - So, assuming you have power and spark:  let's do fuel.
- - Start with the fuses:  all should be clean, along with the
  clips, paying especial attention to the front inside corner
  16a fuse for the fuel pump.
- - Pull the fuse and jump a wire from the positive battery
  terminal to the forward clip that used to hold the fuse.
  The fuel pumps should be audible, and you should hear the
  fuel swooshing through the pressure regulator.
- - If no go, the fuel pump is the most suspect.
- - If this works, try replacing the fuel pump relay - also on
  the outside of the fuse box, per the order described above.

That addresses most of the common modes of failure.  There are
some rare (and obnoxious) modes of failure, such as wire splices
buried in the wire harnesses opening up, but I am betting on either
the 'main' or fuel pump relays.

Have fun!  Larry F.

>Date: Thu, 21 Oct 1999 09:35:10 EDT
>From: Richbauch@domain.elided
>Subject: 87 535i Died
>
>Bimmerphiles...
>
>Driving to work this morning, my car just died!
>
>I replaced the power steering fluid last night and was working around the
>fuse box.
>
>I have access to tools at work, but I don't have my manual.
>
>Can anyone help me diagnose?  How do I check for spark?  How do I check for
>fuel going to the motor?
>
>Any help would be greatly appreciated!!
>
>Thanks in advance,
>
>Richard
>
>

Larry Franks
Issaquah, Washington
'95 540i/6
'86 535i
'83 245 GLT  (Swedish iron)

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