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2021 Mustang GT Fuel Pump Thumping - Roush Supercharged

GWraith

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My 2021 Mustang GT with a Roush Supercharger Phase 2 recently had its ECU calibration updated. After that was done I started to hear this thumping, 3 of them, any time I would open the driver's door when it's been off for more than 5 min. Sometimes it even will occur if I'm just standing near the car with the key.

I originally thought it was the HPFP as it sounded like it was coming from the front right of the car. However, when I had my wife help me locate and video the sound we found it was coming from the driver-side gas tank area so in-tank fuel pump.

I consulted Roush and provided them videos of the noise and they said it should only do that if it's cold not every time.

I have no starting issues when hot and only slightly extended cranking when cold which is normal.

Going from the orginal calibration to Roush's new calibration it fixed the issues present on most supercharged Mustangs of the stumble start when the car is already to temp. This would happen if you went in to the store a few min then came out and started the car again. Its would start but stumble a little before eventually reaching stable idle.

My car is a push start, manual, base model. I upgraded the screen to 8" OEM and sound system speakers/amp. I have also made modifications consistent with the stereo upgrade in FORSCAN but have not touched anything fuel-related in there.

Roush is adamant that their calibration uses Ford's fuel strategy and they didn't modify anything and said I should take it in. They have since gone radio silent when I asked them to let me revert the calibration to the previous version to verify.

Previous to the calibration I never noticed it neither did my wife, she drives it most of the time to school.

Ford dealers in the Tampa area are absolute shit. They want you to leave your car with them for a week or more just to even look at it and most can't "fix" anything for weeks sometimes months out.

Just trying to gauge the community and see if this is seen in other cars across the forum or should I take this in as it may be something in the fuel system beginning to fail? It simply sounds like the fuel pump is priming 3 times and every time I go to use the car.

I should add I live in Florida and low temps is like 60F so not really cold by car standards.

Once the 3 year warranty is up on the Roush Supercharger Im going fully custom fuel system and E85 so as long as this pump lasts 3 years I can ignore it.

Here are multiple links to the video files:

Roush Folder
https://drive.google.com/drive/folders/1pEZLth_rKqW_krzZMTL-h2HI8RxJacY4?usp=sharing

Zip File w/ Both Videos:


Video 1 - MP4:


Video 2 - MP4:
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Andy13186

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My fuel pump makes a noise when I open my car , I think its just priming or something.
 
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GWraith

GWraith

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I have been thinking about this all day. Why are they priming the in-tank fuel pump 3 times? Also, it's so loud that I bet they are not even regulating the voltage. I think this is less of a prime and more of a shock. It sounds as if they are shocking the pump full voltage full bore 3 quick times.

I'm a prior aircraft mechanic and current-day electronics and programmer.

These "hits" are probably producing way more pressure in the fuel system than it needs or wants for that instant. I'm not sure what all the fuel system can handle but I worry about seals and leaky injectors down the road if something like this were to go on for years.

They must have a pressure sensor in the fuel system. Why are they not integrating that into the equation and applying only the necessary voltage to turn the pump to prime the system? What I mean is a 12v pump will still turn at 6V. Why are they not just applying a lesser voltage over a longer time to gradually increase the fuel pressure to prime the system, it would make WAY less noise?

I still believe this issue started happening when the new Roush calibration was put on. Not sure if Ford changed their source code, or Roush made changes.

This is the first of 3 Mustangs 2014,2016,2021, 2 of which were/are boosted, that I had ever heard this happening.

This however is my first Roush boosted mustang.

The kit on this car is 2018+ which we all know is different from the 2017 and older as they do not use a "boost a pump" and simply crank the voltage on the stock fuel pump by using the ECU adjustment to get desired high pressures out of the stock parts.

I have a feeling I'm going to have to put up with the shitty Ford dealerships here in Tampa to get my car looked at, but I dont trust them at all. I have never had a good experience at a Ford dealership. They try to upsell, lie, and skirt warranty work. Which is why I usually do my own reaseach and end up doing the repair / maintenace myself.

For reference this car was purchased from Lebanon Ford, 0 miles supercharger installed, and documented. Then it was truck shipped to my residence in Florida.

I have done the following work myself:

Changed 4" to 8" touchscreen using a 2017 screen and bezel. The current-gen APIM can be converted with software.

Changed out all the speakers for slightly better powerBass speakers. Added a 4 channel JBL Stadium 4 AMP, PRV DSP, 2 Farad Cap, and pioneer loaded 10" sub enclosure. Both positive and negative are straight wired to the battery. With that I made changes in FORSCAN to make the factory stereo output flat and low voltage (RCA) for going into the DSP and changed the chime strategy to IPC only. I tapped the front camera power for the turn-on signal. Changes were also needed in FORSCAN to accommodate the new switch configuration of the bezel.

My final modification was I took a stock active exhaust from a 2018 junkyard donor and fit it on my vehicle. I used FORD actuators with circuit board removed and reversible 12v tapped off the cigarette lighter power so it's only active if the car engine is running. Works flawlessly with a center console switch.

I also added a 12v led bar directly to the battery under the hood. It's a small bar with an old-school 80s hood pop switch that when the hood is up, it's on.

I added pics of the day I took delivery, the stereo before I put in the DSP and my little add-on badge (+5hp).

IMG_20210523_162634.jpg


IMG_20210523_162935.jpg


IMG_20210612_180502.jpg


IMG_20211107_122724.jpg


IMG_20211107_122801.jpg


IMG_20211107_122804.jpg
 
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Cobra Jet

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My 2021 Mustang GT with a Roush Supercharger Phase 2 recently had its ECU calibration updated. After that was done I started to hear this thumping, 3 of them, any time I would open the driver's door when it's been off for more than 5 min. Sometimes it even will occur if I'm just standing near the car with the key.

I originally thought it was the HPFP as it sounded like it was coming from the front right of the car. However, when I had my wife help me locate and video the sound we found it was coming from the driver-side gas tank area so in-tank fuel pump.

I consulted Roush and provided them videos of the noise and they said it should only do that if it's cold not every time.

I have no starting issues when hot and only slightly extended cranking when cold which is normal.

Going from the orginal calibration to Roush's new calibration it fixed the issues present on most supercharged Mustangs of the stumble start when the car is already to temp. This would happen if you went in to the store a few min then came out and started the car again. Its would start but stumble a little before eventually reaching stable idle.

My car is a push start, manual, base model. I upgraded the screen to 8" OEM and sound system speakers/amp. I have also made modifications consistent with the stereo upgrade in FORSCAN but have not touched anything fuel-related in there.

Roush is adamant that their calibration uses Ford's fuel strategy and they didn't modify anything and said I should take it in. They have since gone radio silent when I asked them to let me revert the calibration to the previous version to verify.

Previous to the calibration I never noticed it neither did my wife, she drives it most of the time to school.

Ford dealers in the Tampa area are absolute shit. They want you to leave your car with them for a week or more just to even look at it and most can't "fix" anything for weeks sometimes months out.

Just trying to gauge the community and see if this is seen in other cars across the forum or should I take this in as it may be something in the fuel system beginning to fail? It simply sounds like the fuel pump is priming 3 times and every time I go to use the car.

I should add I live in Florida and low temps is like 60F so not really cold by car standards.

Once the 3 year warranty is up on the Roush Supercharger Im going fully custom fuel system and E85 so as long as this pump lasts 3 years I can ignore it.

Here are multiple links to the video files:

Roush Folder
https://drive.google.com/drive/folders/1pEZLth_rKqW_krzZMTL-h2HI8RxJacY4?usp=sharing

Zip File w/ Both Videos:


Video 1 - MP4:


Video 2 - MP4:
The “thumper” fuel pump “prime” is normal see this thread:
https://www.mustang6g.com/forums/threads/2018-“prime”-when-initially-opening-driver-door.106779/#post-2375824
 

jhunt47

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Mine does the same thing whenever I get close with the key. My 2021 f150 does it as well every time I open the door and sometimes when walking up to it. Yours has probably done it the entire time your just now noticing it. As a former ford tech I use to think I knew more and tried to diag these vehicles every time something came up on them. Now I just drive them until they breakdown and stopped worrying about stuff that wasn’t really problems until it’s a real problem. Sometimes knowing a little about things make it worse than it is.
 

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GWraith

GWraith

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Got a response from Roush they did a side by side comparison of the new calibration. While they said it's not possible to revert to the previous version they have said there is nothing to worry about unless extended cranking or not starting issue develops.

As for the comparison they said they do see some differences that Ford made but that Ford has not released any updated notes on the new changes.

I'll update as I find out more. At least I now know I'm not crazy 😂, well not seriously.
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