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2020 Mazda 3 Cranks But Won't Start - No Fuel Pressure?

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Mike T. · rep 0 · May 25, 3:31 AM · 1 replies · solved · Question

Vehicle: 2020 Mazda 3 Preferred

Hi everyone,

I'm having a frustrating issue with my 2020 Mazda 3 Preferred sedan. This morning, I went to start it, and it just cranks and cranks but won't fire up. It sounds like it's not getting any fuel.

There are no check engine lights on, and I haven't noticed any prior issues. The battery seems strong as it cranks vigorously. I tried cycling the ignition a few times to prime the fuel pump, but no luck. I don't hear the typical fuel pump hum when I turn the key to the 'on' position.

Could this be a bad fuel pump, or is there something else common on these models that would cause a no-start condition like this? I'm debating whether to try and troubleshoot it myself or just get it towed to the dealer. Any thoughts or diagnostic steps would be helpful!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 25, 3:31 AM

0

ClearTheCode admin answer:

A crank-no-start condition, especially without a Check Engine Light, often points to an issue with either the fuel system, ignition system, or less commonly, the immobilizer. Given your observation about not hearing the fuel pump, the fuel system is a strong candidate.

  1. Check Fuel Pump Fuse/Relay: Locate your vehicle's fuse box (usually under the hood and/or inside the cabin). Find the fuse and relay for the fuel pump and inspect them. A blown fuse or faulty relay can prevent the pump from operating. You can often swap a relay with a known good one (like the horn relay) for a quick test.
  2. Verify Fuel Pressure: If you have access to a fuel pressure gauge, connect it to the fuel rail to confirm if there's sufficient pressure during cranking. A healthy fuel system should build pressure quickly. Lack of pressure strongly indicates a fuel delivery problem.
  3. Immobilizer System: While less common without a specific warning light, a fault in the immobilizer system can prevent the engine from starting. Ensure you're using the correct key and try a spare key if you have one. Look for any flashing security lights on the dashboard.
  4. Crankshaft Position Sensor: A failing crankshaft position sensor can prevent the engine control unit (ECU) from knowing when to fire the injectors and spark plugs, leading to a crank-no-start. This can sometimes happen without immediately triggering a CEL, but often will eventually.

When to see a shop: If you've checked the fuses/relays and still have no fuel pressure, or if the problem persists after trying a spare key, it's best to have your Mazda 3 towed to a professional. A mechanic can perform more in-depth diagnostics, including checking for power at the fuel pump, testing the immobilizer system with specialized tools, and diagnosing other potential sensor failures that might not immediately trigger a CEL.

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