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2022 Ram 1500 3.6L - Cranks But No Start, No Fuel Pressure

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Sarah K. · rep 0 · May 22, 3:30 AM · 1 replies · solved · Question

Vehicle: 2022 Ram 1500 Big Horn 3.6L Pentastar

Hi everyone,

My 2022 Ram 1500 with the 3.6L Pentastar engine (Big Horn trim) suddenly won't start. It cranks strong, the battery is good, but it just won't catch. It sounds like it's not getting any fuel. I checked the fuel pressure at the rail, and it's basically zero.

I've already checked the fuel pump fuse (it's good) and swapped the fuel pump relay with another identical relay from the fuse box, but no change. I don't hear the fuel pump prime when I turn the key to the 'on' position. Is there anything else I should be looking at before I assume the fuel pump itself is dead? The truck only has 30,000 miles on it, so this is pretty frustrating.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 3:30 AM

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ClearTheCode admin answer:

It sounds like you've done some good initial troubleshooting by checking the fuse, relay, and confirming no fuel pressure. A 'crank but no start' condition with zero fuel pressure and no pump prime sound strongly points to a fuel delivery issue. Here's a breakdown of potential causes and next steps:

  1. Fuel Pump Itself:

    • Cause: The most direct cause of no fuel pressure and no priming sound is a failed fuel pump. Even at 30,000 miles, component failures can occur, though it's less common.
    • Action: If you've confirmed power is reaching the pump (see step 2), then the pump itself is the likely culprit. Replacing the fuel pump assembly (which includes the pump, sender, and filter) is usually the solution.

  2. Wiring to Fuel Pump:

    • Cause: A break, short, or corrosion in the wiring harness leading to the fuel pump can prevent it from receiving power, even if the fuse and relay are good.
    • Action: You'll need a multimeter to test for voltage at the fuel pump connector. Accessing the connector usually requires dropping the fuel tank or accessing it through an access panel (if your specific model has one). You should see battery voltage for a few seconds when the key is turned to 'on'.

  3. Fuel Pump Driver Module (FPDM):

    • Cause: Many modern vehicles, including your Ram, use a Fuel Pump Driver Module to control the fuel pump's speed and pressure. If this module fails, it won't send the necessary signals to the fuel pump.
    • Action: Locate the FPDM (often mounted on the frame rail or near the fuel tank). Check its electrical connector for corrosion or damage. While less common than the pump itself, a faulty FPDM can mimic a dead fuel pump.

  4. Ignition Switch or PCM Issue:

    • Cause: In rare cases, a faulty ignition switch might not be sending the 'run' signal to the PCM, which then fails to activate the fuel pump. Similarly, a PCM (Powertrain Control Module) failure could prevent the pump from being commanded on.
    • Action: These are less likely but possible. A professional diagnostic tool can check for related trouble codes or confirm if the PCM is commanding the fuel pump on.

When to See a Shop: If you're not comfortable testing wiring or dropping the fuel tank, or if you've confirmed power to the pump but it's still not working, it's time to visit a professional mechanic. They can safely access and replace the fuel pump, diagnose FPDM issues, and perform more advanced electrical checks.

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