Saab: Saab 900i, 16v, 1991 Wont run, fuel level gauge, mass air flow sensor

Question
QUESTION: :
1991 Saab 900i, 3 door, 16v, 2.1 liter engine
Chassis number *YS3AC35D3M5010225*

Problems: Mass Air Flow sensor burned out, motor stopped, car wouldn't run.  filament was burned through, ceramic case blistered, intense heat, completely dead. I replaced it with a tested used unit. Based upon the ECM readings, I found several rubber vacuum hoses leaking and replaced them, checked all vacuum connections.... all okay. Checked and cleaned the engine IAC idle adjustment valve. Replaced the oxygen sensor with a new one. Fuel flow appears okay.
Then I found a burnt fuse in the panel under the rear seat, replaced that, don't know what it went to, it was not in the normal fuse panel in the engine compartment. Then found a corroded connection to the fuel level gauge in the gas tank. Repaired that. Now dash check light wont respond to testing, just stays on. Replaced EMC with tested unit, no change. Swapped fuel relays with a spare unit.
Where do I go from here? When the car does runs, it runs outstandingly well.

Testing: I made a fused testing wire and connected it to the Bosch LH 2.4.2.4.1.2.4.2 ECM motor computer test unit under the rear seat and read the fault codes from the computer. The codes are:
12111-  learning fault in Lambda;
12112- learning fault in Lambda;
12223-too lean;
12231- false reading, no ignition;
12241-False, ignore;
I read the codes, clear the ECM computer memory, the yellow Engine Fault light comes after restart and stays on, the car runs fine for a few days and then the engine cuts out completely while driving... nothing... dead.  
I repeat the procedure, get the same faults, mostly "learning" faults, clear the computer... and so on.

Finally, after replacing and checking everything, the Engine Check light stays on constantly, wont respond to the checking procedure anymore, and the car wont start at all. Is there a manual check procedure for the fuel relays?

Help please, I'm finally lost
Bob Carignan


ANSWER: Bob:
 I recall that I'd answered with a simple procedure to check the fuel pump relay  in this forum about a year ago.  In short, it involves removing fuses Number 27 and 30 and connecting the outboard terminal of fuse 30  to the inboard terminal of fuse 27. If the fuel runs, then it or the wiring driving it is faulty. If the pump does NOT run, then the problem is in the wiring to the pump or the pump itself.  
     Hope this helps,
         Jerry

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

QUESTION: Jerry,
Thanks, the fuse check worked, replaced one relay and the car now runs. New problem now, consistently after driving a short distance the 'Check Engine' light comes on, codes are always:12111-Learning fault in Lambda; 12223-Too lean; 12231-False reading, no ignition; 12241-False, ignore;
I clear the computer, run the car a while and then they come on again, always the same codes, same order. Any suggestions? I've gone through the engine, hoses, and sensors several times, am I missing something?  Thanks in advance. Bob

Answer
Bob:
  I would start with checking out the O2 sensor...a simple test is to remove it and apply a propane torch flame to the sensing element; w ith a good sensor, the output voltage, as measured on a high impedance digital voltmeter, should rise to approximately 0.4 volts and quickly fall back upon removal of the flame.
 If this checks ok, then you'll need to check out the chassis wiring, wire by wire. If you need a schematic, I can scan it in and send it.
         Jerry