Volvo GLE 740 no knock sensor 1990 will not start?

If your 1990 Volvo GLE 740 won't start and is missing a knock sensor, it could lead to ignition timing issues, but the absence of a knock sensor alone typically wouldn't prevent the engine from starting. Check for other common issues, such as fuel delivery problems, ignition system failures, or electrical issues like a dead battery or faulty starter. Additionally, inspect the fuses and relays related to the fuel and ignition systems. If everything else checks out, consider having the engine's diagnostic codes read for more specific insights.