Error Code U0109 Communication lost with fuel pump

[Stringcheese]

I have a check Engine light, an illuminated wrench, and a U0109 Code 'Communication with fuel pump lost'

So, First thing is I changed the fuel pump and sending unit. Then I bought an OBD MX+ and used FORscan to troubleshoot and clear the code.

Code popped back up, repeatedly.

Car runs and drives fine. Fuel gauge works properly.

Any ideas where I should look for an issue? PCM failing?

Where is the plug on the PCM side of the fuel pump circuit?

Thanks!

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[kryptto]

What year? There were model years I believe 2010-2013 with fuel pump relay issues

 

[Stringcheese]

What year? There were model years I believe 2010-2013 with fuel pump relay issues

View attachment 88517

2016

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[Stringcheese]

What year? There were model years I believe 2010-2013 with fuel pump relay issues

View attachment 88517

Where's the fuel relay? Fuse box?

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[kryptto]

Nope back where the pump was, you drop the passenger seat back, use a tool to lift the fabric clips. It's right next to the door frame. Two screws and pop it out. I threw the factory installed one in the trunk. When they go you can be completely stranded. About $75 if I recall. The 2014 models had some of the bad relays in the early built models. Was a safe than sorry replacement for me.

PS, Some folks online including me noticed an increase of line pressure. Nothing huge... but couple psi on average.

 

[Stringcheese]

Nope back where the pump was, you drop the passenger seat back, use a tool to lift the fabric clips. It's right next to the door frame. Two screws and pop it out. I threw the factory installed one in the trunk. When they go you can be completely stranded. About $75 if I recall. The 2014 models had some of the bad relays in the early built models. Was a safe than sorry replacement for me.

PS, Some folks online including me noticed an increase of line pressure. Nothing huge... but couple psi on average.

Do you think that could even interfere with the fuel pump talking to the PCM?

I mean I changed the pump and sending unit. I have it undercoated every year, so that would lower the chance of a rotted wire. Such an oddball problem.

I may as well look into the relay, they can't be more than a frw bucks. But the car is running and I am getting fuel pressure and usage in the PIDs.

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[kryptto]

Hmm well generally the relay when it fails will cause the car to not start. BTW not to make u paranoid there is a ford tech many of us follow on YT might make u rethink that decision....

 

[kryptto]

Do you think that could even interfere with the fuel pump talking to the PCM?

I mean I changed the pump and sending unit. I have it undercoated every year, so that would lower the chance of a rotted wire. Such an oddball problem.

I may as well look into the relay, they can't be more than a frw bucks. But the car is running and I am getting fuel pressure and usage in the PIDs.

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You could try and reset the KAM keep alive memory - the SCT can do that.

Read this, and hope it helps explain.

 

[Stringcheese]

Hmm well generally the relay when it fails will cause the car to not start. BTW not to make u paranoid there is a ford tech many of us follow on YT might make u rethink that decision....

I use a mineral oil/wax based coating

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[Stringcheese]

Well, the relay fixed the communication error.

Of course I reset the vehicle completely with my ned OBDLink MX+ because I thought, why not!

Now it runs and no engine codes, but continously stalls at idle. I wonder if I kinked one of those impossible hoses on the fuel pump. I tried not to. Any ideas?

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[kryptto]

Well, the relay fixed the communication error.

Of course I reset the vehicle completely with my ned OBDLink MX+ because I thought, why not!

Now it runs and no engine codes, but continously stalls at idle. I wonder if I kinked one of those impossible hoses on the fuel pump. I tried not to. Any ideas?

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get a code from the computer....

 

[Stringcheese]

Okay, here's a screenshot of my fuel PIDs at idle.

Basically car slowly loses RPM until stall, repeatedly.

Otherwise runs great

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[Stringcheese]

Ugh app wants me to.pay to.post a photo. I don't have the time right now

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[Lurch.sho]

Ugh app wants me to.pay to.post a photo. I don't have the time right now

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you can upload pictures for free on a browser, i use safari on my phone or google chrome

 

[Stringcheese]

Once engine is up to temp, idles low but no stalling. Struggles a little.

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[Stringcheese]

you can upload pictures for free on a browser, i use safari on my phone or google chrome

I gotta get to work this morning but will post screenshot later today. Thanks for the heads up!

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[Stringcheese]

get a code from the computer....

Not throwing any codes

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[Stringcheese]

Here are PIDs pertaining to fuel

 

[Stringcheese]

Also, the car is shuttering briefly when I go from steady gas pedal to letting off.

 

[Texas Marauder]

All the pids look ok. Check for a vacuum leak.