My 1976 Cadillac Eldorado Cranks but Doesn’t Start. What Could Be the Cause?

Written by

Mia Bevacqua, ASE Certified Master Automobile Technician

Automotive Subject Matter Expert at CarParts.com

Updated on October 12th, 2023

Reading Time: 3 minutes
Summary
  • Your 1976 Cadillac Eldorado might crank but refuse to start because the electronic control module (ECM) isn’t pulsing the injectors.
  • A faulty sensor, wiring issues, or ECM failure are possible causes why the ECM is failing to pulse the fuel injectors and preventing your Cadillac Eldorado from starting.
  • Another possible reason why your 1976 Cadillac Eldorado cranks but won’t start is an engine mechanical problem, such as a damaged timing chain.

Q: I have a 1976 Cadillac Eldorado 500 with an 8.2L fuel-injected engine. The engine cranks but doesn’t start. Both fuel and spark are present. What could be preventing the engine from starting?

– Rod T McClashie from Mesa, Arizona

Issues such as a faulty sensor (e.g., engine speed sensor), a wiring problem, or an issue with the ECM itself could prevent your vehicle engine from starting.

A: Hi, Rod. When you say the engine is getting fuel, I’m guessing you mean that there is good fuel pressure. What you might be missing, however, is injector pulse—the onboard engine management system “pulsing” the injectors on.

Your vintage Cadillac has a fairly modern electronic fuel injection system that includes an electronic control module (ECM), sensors, and fuel injectors. The ECM uses input from the sensors to determine when to fire the injectors. 

One of the easiest ways to check for injector pulse is with a noid light. You simply disconnect the electrical connector from the injector, then insert the noid light into the female side of the connector. Crank the engine and monitor the noid light. Repeat this test on a few different cylinders. If the light does NOT illuminate during testing, there’s no injector pulse, which indicates the ECM is not commanding the injectors on. 

From there, you’ll need to determine why the ECM is not pulsing the injectors. The issue could be a faulty sensor (e.g., engine speed sensor), a wiring problem, or an issue with the ECM itself. 

The ECM uses input from the sensors to determine when to fire the injectors.

The other possibility is that you have an engine mechanical problem, such as a damaged timing chain, preventing the engine from starting. But if the engine cranks normally, I would lean more towards a lack of injector pulse. 

Good luck! 

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