Fuel System Issues; New Pump; New FPDM;

[ZackaryLamberson]

Hello,
2014 Ford Fiesta SE 1.6 Liter Naturally Aspirated Automatic transmission Sedan.

I can't get my fuel system to work. I have replaced the fuel pump twice and the FPDM (Fuel Pump Driver Module).

I first replaced the fuel pump and it actually ran for about 30 minutes and I thought I was good. The next day it didn't work. I replaced it again thinking it was a lemon because I bought it off amazon (I got the second from O'Reilly's) and it still didn't work. I tested resistance to ground on the pump negative pin and found it was high so I thought it was the FPDM and replaced it. After I replaced the FPDM and cleared the codes the pump ran for about 10 seconds and the car started and quit shortly after.

My most recent troubleshooting step was to look through the wiring and connector diagrams and jump/short the chassis ground and 12V+ supply that goes to the FPDM with the "managed" power pins for the fuel pump (i.e. just give the fuel pump straight power and ground), and it ran. I started the car it idled and I could rev it fine.

At this point I think I can be reasonably confident that the pump, FPDM, and the wiring between the pump and FPDM is fine. Currently the only other "culprits" i have in mind are: the PCM (powertrain control module), RCM (Restraint Control Module), and the wiring between the FPDM and the PCM.

I have been getting P0627 (Fuel Pump Control Circuit Open). I briefly got P2195 (O2 Sensor Signal Stuck Lean) but I figure that's because of the fuel delivery issues.

I haven't gotten any codes about the RCM, but I know that the RCM can immobilize the car.

I have tested continuity between the FPM pin on the FPDM connector and the FPM pin on the PCM connector. I have tested continuity between the FPC pin on the FPDM connector and the FPC pin on the PCM connector. (The two wires going between the PCM and FPDM have good continuity when measured from their connectors).

At this point I'm leaning towards getting a new PCM, however i've already thrown two (three if you count the repeat fuel pump) parts at this and I don't want to just buy the next part that it could be. Any help is appreciated.

 

[Handy Andy]

You will need to verify the FDPM is bad, by observing the connector, once unattached - to observe voltages, then attached to see voltages when it supposed to be on.

This also means a continuity check - if Ground is good, it is the only one that has a separated ground from one of the many main ones located under the seats - the Pump's ground is behind the seat in the wall of the rear passenger seat well at the passenger rear door.

The OCCAM'S Razor event is near here...once all the other things that can be a problem are removed, the one left behind is the obvious one to fix.

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Since you got the pump to work wired in directly - the FPDM is a control loop for the Fuel pump and uses the PCM to help it shut down or keep running - The SRS / Airbag system if deployed, will tell the fuel pump to turn off and stall the motor to prevent a fire but if it's been damaged - it can fail the FPDM again by damaging a loop detect circuit keeping the pump from ever turning back on.

To help with this Fiestas have two types of Fuel pumps - both have internal pressure regulation - one need the FPDM to regulate the speed - using pulses - to monitor the regulation - while another simply runs on 12V and shuts itself off when it it's pressurized or it thinks it has pressure - therefore it's loop relies on the Fuel Pump Relay from the PCM to tell it to go on or off and it runs as a standalone. The Former does not and although both will not over-pressurize. One will run all the time and not shut off until the power is disconnected by the relay. The PCM will have a different wire to run the pump and note the color code - so make sure the pump you're using is the correct one.


Not because the FPDM is faulty, you may have the wrong type of pump because it (PCM) looks to a different sensor so if the Sensor is faulty - the pump will never kick on because the PCM thinks it's pressurized. (Open connection showing High or Short to Ground showing LOW) The above is inclusive to turbo - but doesn't mean it is not used in the other Trim lines per the years of production; SE, S Titanium or ST.

So if the MAF sensor is ok, and you have the 7.5 Amp fuse still good, and the Relay can be powered to make it turn on - then the only thing left is to verify the Sensor (if there is one) is still good. Else an open ground at the Relay, or Bad relay or wire to PCM's Engine controls is bad.

• Adding This In Just To Clarify: IT may sound incredulous that Ford would produce two pumps for the same vehicle, but they made several types of engines used in them, including GDiT (Direct-Injection) which requires a different approach to making the fuel able to be injected in a compressed state or during high-compression strokes.