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I've had a 2011 Ford Mondeo 2.3L for about 18 months, and the fuel pump has failed for the third time. Each time the same story - the car drives fine, turn off the engine, leave the car, get back in the car, try to start and not a jot of fuel coming through - pump failed.

The car will be towed off to Ford tomorrow, but I'm worried that just changing the pump will lead to the same thing happening again. The tank has been cleaned out (although nothing wrong found there), and it always has sufficient fuel levels, and I have only used 91 unleaded. Any ideas?

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  • Have they been changing the fuel filter when they change the pump?
    – mikes
    Commented Jun 26, 2016 at 11:19
  • The first time, yes, but the second was just a straight pump change I believe.
    – Lee
    Commented Jun 26, 2016 at 12:24

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I agree with Arturs answer about high fuel pressure but I suspect a different root cause for the high pressure. In your car there is a fuel pressure sending unit. This little box is attached to the fuel line and monitors fuel pressure. It send a message to another device that controls the fuel pump. This second device a Fuel Pump Driver Module (FPDM) uses Pulsed Width Modulation (PWM) to tell the fuel pump how fast to run.

I'm guessing those signals are bad leading to excessive pressures. My guess would be that a faulty pressure sensor is screwing things up but it could also be the driver module or a problem in wiring between these units. Do note it's possible the FPDM function has been moved to be integral to your Powertrain Control Module (PCM).

I would start the investigation by reading the output of the fuel pressure sender on a volt ohm meter and/or a review of the signal going into the fuel pump with an oscilloscope.

Do let us know what you find.

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  • The car is running once more. The Ford garage found a loose connection in the wiring loom to the fuel pump which has now been replaced. They seem confident that the source of the problem has now been identified - many thanks @Arturs and zipzit. Fingers crossed, the problem is sorted.
    – Lee
    Commented Jul 1, 2016 at 13:04
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We have a 2008 and (with my previous experience with faulty fuel pumps) assumed it was another failing pump so ordered a new one, but it didn't arrive on time. However I had pulled the tank out (yes you need to remove the tank to access the pump - no inspection hatch like other models) and noticed while waiting for the new pump that the connections on the top of the pump connector were melted, the terminals inside were also melted.

I worked out that the double ended connector pins that goes thru the plastic pump lid are the wrong size for the push on spade connectors. so, I cut the internal pump connectors off (leaving the wire as long as possible) and drilled a small hole through the plastic lid and joined the wire the the short harness on top of the tank - eliminating the double socket completely (and joining the fuel level sender wires the same way).

Remember to take photos including the colour coding of the pump wire/polarity or the fuel pump won't pump! Then cover over the holes you created with the ole' hot glue gun! or a suitable fuel proof sealant.

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I see 2 reasons. 1. Bent or damaged fuel line between a fuel pump and engine, 2. Previous driver might increase a fuel pressure hoping that it will inject more fuel and make a car more powerful.

To kill an electric motor you need to overload it. If the tank is clean, there is only one way left how to overload it. You can ask in garage to check a fuel pressure in fuel rail and straight after fuel pump (if they can). And see the difference.

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  • Nice one, thanks will talk to them tomorrow. Doubt it was the previous driver mucking about..is a station wagon, so no go faster stripes :-)
    – Lee
    Commented Jun 26, 2016 at 12:28

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