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Saab/88 saab 900 starts then dies immediately


QUESTION: Sounds fine on start up, runs briefly (about 5 to 10 seconds) then dies.  Runs fine with fuel pump jumpered at fuses.  I have had ecu repaired and replaced both the system relay and fuel pump relay.
Any additional suggestions?
Thank you.

 Sounds like the only thing left is the wiring. Since the engine runs satisfactorily with the fuel pump relay jumpered, then either:
 a. The fuel pump relay control coil (terminal 86) is not getting 12 v from terminal 87 of the system relay OR,
 b. The connection between terminal 85 of the fuel pump relay which goes to pin 17 of the ECU is faulty (the ecu keeps pin 17 at ground to sustain fuel pump operation during running).
     Hope this helps,
         Good Luck,

---------- FOLLOW-UP ----------

QUESTION: Jerry thank you for your original reply.
a. There is 12 v at fuel pump relay terminal 86.
b.  I have continuity between fuel pump relay terminal 85 to ecu pin 20 but not to ecu pin 17.  As per townsend I do have 12 v between ecu pin 4 and ecu pin 17.  There is also 2 - 3 v AC between ecu pin 1 and ecu pin 17 when cranking.  
therefore the question:  what would prevent fuel pump relay terminal 85 from connecting to ecu pin 17?  In other words what does the wire from 85 go through before getting to 17 or is it a straight connection?
Thanks for your assistance.

Jim:  Please accept my apology for giving you bad info...I looked at the reference for the 1987 SAAB..not the 1988.  For the 1988, there should be a connection from fuel pump relay 85 to pin 20 of the ECU ONLY! Pin 17 of the ECU is a hard ground.
  I am attaching a scanned in complete schematic which I hope will be more effective than verbal descriptions.


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Jerry Schwell


Most anything about SAAB 900's 1990 and earlier only, except for automatic transmission info. Also, I have lotsa vintage parts.


I have rebuilt many dozens of SAABS, from 1970's to 1990's.

BSEE grad work in electronics and underwater acoustics.

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