DO NOT REPLACE YET
No spark + no injector operation
Start above both outputs: verify PCM power-up, feeds/grounds and distributor reference architecture. The 1994 diagnostic system uses separate high- and low-resolution distributor information.
LT1 · 1994 · CRANK / NO-START
1994 LT1 Cranks but Will Not Start
The first useful split is not “is the Opti old?” It is what the engine loses while cranking.
APPLICATION: 1994 Firebird / Formula / Trans Am 5.7L VIN P LT1 only.
Injector operation present, spark absent
That observation changes the path. Continue into ignition-control/module/coil/output diagnosis instead of automatically condemning the distributor.
Spark + injector operation present
Move toward fuel delivery, actual spark distribution/timing, flooding, sensor plausibility and mechanical condition rather than repeating the same ignition test.
Start with GM preliminary inspection
GM's 1994 procedure calls for a charged battery, adequate uncontaminated fuel, serviceable plugs/filter, and careful inspection for disconnected, pinched, burned or chafed wiring before deeper diagnosis.
1994 workflow
- Perform the 1994 Diagnostic Circuit Check and retrieve supported DTCs.
- During cranking, observe spark and injector operation together.
- If both are missing, prove system powers/grounds and exact-year distributor reference circuits.
- If spark alone is missing, isolate ignition-control/module/coil and secondary output.
- If both are present, verify fuel delivery and whether the engine is over-fueled, incorrectly distributed/timed, or mechanically unable to run.
- Repeat the original no-start condition after repair.
DO NOT REPLACE YET
Do not replace the fuel pump, ignition parts, security components, PCM or sensors just because the engine cranks but will not start. First prove which required input—fuel, spark, injector command, synchronization or enable—is missing.
PARTS VERDICT
Replace only the component/circuit that fails its dedicated test. A no-start is a system state, not a parts verdict.
REPAIR → VERIFY
After repair, verify cold and hot restart, confirm the engine starts without extended crank, and recheck for returning DTCs or loss of the same required input.
FPV DIAGNOSTIC RULE
SYMPTOM → TEST → ISOLATE → PROVE → PARTS VERDICT → REPAIR → VERIFY. A code, symptom or commonly failed part is not proof by itself.
AFTER THE FAILURE IS PROVEN
Use the proven failed branch—not the original symptom—to choose the replacement. Go from diagnosis to the Parts Verdict →