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2017 Mazda 6 Stalling and Hard Starts - Fuel System?

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Mark S. · rep 0 · May 22, 4:48 AM · 1 replies · solved · Question

Vehicle: 2017 Mazda 6 Touring

Hi everyone,

My 2017 Mazda 6 Touring (2.5L engine) has been acting up lately. For the past few weeks, I've noticed it's getting harder to start, especially after it's been sitting for a while. It cranks for a few seconds longer than usual before finally catching.

More concerningly, it stalled on me twice last week while driving at low speeds, once at a stop sign and once pulling into a parking spot. It also feels like it's losing power under hard acceleration sometimes. No check engine light yet, but I'm worried about getting stranded.

Could this be a fuel pump issue, or maybe something else in the fuel system? Has anyone experienced similar problems with their Mazda 6? Any diagnostic tips or common culprits would be great!

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 4:48 AM

0

ClearTheCode admin answer:

Hard starts, stalling, and loss of power are classic symptoms of issues within the fuel delivery system. While a check engine light isn't on yet, these problems can quickly escalate. Here's a look at the likely culprits and what to do:

  1. Common Fuel System Problems:

    • Failing Fuel Pump: A weak or failing fuel pump is a primary suspect. It might not be delivering adequate fuel pressure to the engine, especially during startup or under load. This can lead to hard starts, stalling, and a lack of power. You might hear a faint whining sound from the rear of the car before it completely fails.
    • Clogged Fuel Filter: While many modern Mazdas have a 'lifetime' fuel filter integrated with the fuel pump, if yours is a separate, serviceable unit, a clogged filter can restrict fuel flow, causing similar symptoms.
    • Fuel Pressure Regulator: A faulty fuel pressure regulator can cause inconsistent fuel pressure, leading to both lean and rich conditions, affecting starting and performance.
    • Clogged Fuel Injectors: Dirty or clogged fuel injectors can disrupt the proper spray pattern and fuel delivery to individual cylinders, leading to misfires, rough idle, and power loss. This might eventually trigger codes like P0171 (System Too Lean).
    • Relay/Wiring Issues: Less common, but a failing fuel pump relay or wiring issue could intermittently cut power to the fuel pump.

  2. What to Do:

    • Listen for the Fuel Pump: When you turn the key to the 'on' position (before starting), listen for a brief hum or whirring sound from the rear of the car. This is the fuel pump priming. If you don't hear it, or it sounds weak, it's a strong indicator.
    • Check for Codes: Even without a check engine light, a pending code might be stored. Use an OBD-II scanner to check for any pending codes, especially related to fuel pressure (e.g., P0087 - Fuel Rail/System Pressure - Too Low).

  3. When to See a Shop:

    • Immediately: Stalling is a safety hazard. Do not delay in getting your Mazda 6 inspected. A mechanic can perform a fuel pressure test to definitively diagnose if the fuel pump or regulator is failing. They can also check for any other underlying issues that might be contributing to the problem. Addressing this quickly will prevent potential breakdowns and ensure your safety.
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