The fuel pump in my 98 Mercedes ML 320 died last summer. I replaced it then, but now it's having issues. When I turn the key slowly, I can hear the pump kick in, but when the starter kicks in it shuts back off. The engine will start for 4-5 seconds, then stop. I've put my multimeter on the electrical lines, and it reads 5v on the gauge lines and 12 volts on the power lines... but only for those same 4-5 seconds. I've checked the relay and fuse and both look good.

Where else can I look?

  • Not sure about the MB, but most vehicles will run the fuel pump for a few seconds KOEO, then stop powering it until you actually start the vehicle. You're saying, even after you start the vehicle, the pump only gets power for the 4-5 seconds? Have you put a fuel pressure gauge at the fuel rail to see what the actual reading is when you start it? Mar 4, 2018 at 15:42
  • @Pᴀᴜʟsᴛᴇʀ2 "KOEO"? What does that mean? And I'll check the pressure on the rail.
    – Jim Green
    Mar 4, 2018 at 15:46
  • KOEO = Key On; Engine Off Mar 4, 2018 at 16:13


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