2020 Acadia Denali cranks but won't start - no fuel pressure?

ClearTheCode admin answer:

It sounds like you're experiencing a classic 'crank, no start' condition, with a strong suspicion of a fuel delivery issue, especially since you don't hear the fuel pump priming. Here's how to approach the diagnosis:

1. Confirm Fuel Pump Operation:

   • Diagnosis: The absence of the fuel pump hum is a strong indicator. Modern vehicles typically prime the fuel system for a few seconds when the ignition is first turned to the 'ON' position (before 'START').
   • Action: Have a helper turn the key to 'ON' while you listen closely near the fuel tank (often under the rear seat or cargo area). If there's no hum, it's likely the pump isn't receiving power or is faulty.

2. Check Fuel Pump Fuse and Relay:

   • Diagnosis: Even if fuses 'look' good, a hairline crack or internal fault can occur. The fuel pump relay is a common failure point that prevents power from reaching the pump.
   • Action: Locate the fuel pump fuse (check your owner's manual for its exact location, usually in the underhood or rear fuse box) and test it with a multimeter for continuity. For the relay, you can often swap it with another identical, non-critical relay (like the horn relay, if it's the same type) to see if the problem resolves. If the Acadia starts, you've found a bad relay.

3. Inspect Fuel Pump Wiring:

   • Diagnosis: Damaged or corroded wiring to the fuel pump can interrupt power flow.
   • Action: While more difficult to access, a visual inspection of the wiring harness leading to the fuel pump module (often accessible from underneath the vehicle or by removing the rear seat) can sometimes reveal obvious damage.

4. Test Fuel Pressure (if possible):

   • Diagnosis: If you have access to a fuel pressure gauge, connecting it to the Schrader valve on the fuel rail (if present) will definitively tell you if fuel is being delivered at the correct pressure.
   • Action: A healthy fuel system should show pressure when the ignition is on. No pressure confirms a fuel delivery problem.

When to See a Shop: If you've checked the fuses and swapped the relay without success, or if you can't access the fuel pump to confirm power, it's time to call for a tow to a professional mechanic. Diagnosing and replacing a fuel pump can be complex, often requiring specialized tools and knowledge, especially if it's an in-tank pump. A professional can also rule out other less common issues like a faulty crank position sensor or engine control module (ECM) that could mimic fuel delivery problems.