here's the diagnosis for 312. i'd be REAL suprised if this is the reason for the no start. please note pictures are missing as the links would not copy and paste.

1990 Volvo 760 L4-2320cc 2.3L SOHC Turbo VIN 87 B230FT
Vehicle Level Powertrain Management Computers and Control Systems Testing and Inspection Diagnostic Trouble Code Tests and Associated Procedures Bosch System [LH/EZK] DTC 3-1-2


DTC 3-1-2
Notes

EP. Diagnostic trouble code (DTC) 3-1-2 MFI LH 2.4

3-1-2 No knock enrichment signal from distributor ignition (DI) system





DTC conditions:
When attempting to start the engine the DI system control module sends an Ignition signal to terminals 1 and 28. This is to check that the wiring to terminal 28 is unbroken. A DTC is logged if the signal is missing.

Causes of fault:
Break or short circuit in the wiring between DI#4 and MFI#28

Fault symptoms:
Normally no fault symptoms.

EP1






Connecting the test box to DI EZ 116 K


Ignition off.
Remove fuse 1 (or 31).
Connect the test box to DI.
Continue with Checking the signal from DI EP2.
EP2






Checking the signal from DI EZ 116 K


Connect the control module.
Put in fuse 1 (or 31).
Ignition on. Connect a voltmeter between #4 and #20.
The voltmeter should read approx. 600-900 mV.

If this value is OK:


Continue with Checking the wiring between DI and MFI EP3.
If the reading is 0 V:


Check the wiring between DI#4 and MFI#28 for grounding in accordance with NA3. See: Component Tests and General Diagnostics\N. Other Electrical Fault Tracing\NA. Checking the Wiring
EP3






Checking the wiring between DI EZ 116 K and MFI LH 2.4


Operate the starter motor and take readings from the voltmeter. The voltmeter should read approx. 6 V.
If this value is OK:


Check the wiring between DI#4 and MFI#28 for breaks in accordance with NA2. See: Component Tests and General Diagnostics\N. Other Electrical Fault Tracing\NA. Checking the Wiring
If the reading is incorrect:


Try using a new control module. ----end of testing.

ezk is bosch speak for ignition control system. mercedes uses ezl. porsche has a different ezk. di and mfi is volvo speak for ignition control unit and fuel injection control unit. numbers refer to pins on each ecu. test box refers to a breakout box. i've got 1, but i'm a pro. damn few shops have them. the breakout box sits between the harness and whichever ecu needing testing. it allows you to use a voltmeter to check signals between the sensors, grounds, etc. while the key is off, on or starting, whichever is needed for whatever pin. now for the easy part-i've never seen an ezk control unit fail. nor do the harnesses break on the 89-ups like they do on the 81-88 cars. and again, a bad knock sensor won't keep the car from starting unless, and this is a real stretch, the sensor itself is sooooo screwed up that it's telling the ezk to retard the ignition sooooo far that thing's just won't happen when they are supposed to. again, big stretch. also, only time i saw 214 post was when a bolt got loose in the bellhousing and screwed up the reluctor ring on the flywheel. and i've done a bunch of crank sensors on the 89-up cars, with never a 214 seen.

you don't mention-
1-if you have spark,
2-you hear the fuel pump run,
3-have fuel pressure and what it is,
4-the timing belt is where it belongs on the engine, i.e. the covers are off and the marks line up. don't used the balancer for tdc, unless it's BRAND NEW. the b230 balancers slip and the marks move,
5-WHY the other items were replaced except because you saw it here,
6-WHAT BRANDS were used with WHICH new items, suprisingly important.

information is key. good luck, chuck.