Low Fuel Pressure (WOT ONLY)

[a10jay]

2019 Mustang GT (14K Miles)
CAI, Headers, E85, Lund Tune
Stock Injectors
Stock Manifold
DW400 Fuel Pump

Stock fuel pump was replaced due to failing. Replaced it with a DW400 and ran into low fuel pressure issues at WOT. Assuming it was a faulty fuel pump, I replaced it AGAIN and problem still persists.

Replaced the fuel pump 2x, fuel lines to the fuel pump outlets 2x, and fuel pump driver module. Inspected and checked the whole fuel pump assembly/hat for any leaks, cracks, pinched lines, and ect… countless times. All the ground wires, fuses, and relays are all good. All stock fuel injectors checked out to be good.


Datalog Details:
Fuel pressure drops from 80 to 70 at 5400 rpm’s. Drops to mid 60s at 6000rpms. Drops to 54 at 6400rpms. Drop to 45 at 7000 rpm’s and then 43 at 7300 RPMS. Code P008A. Voltage is 13.2V-13.5V.

Anyone have any ideas or solutions? I’ve already discussed my problem with Lund and two mechanics that work on LS/FORD but neither one of us can find a solution to the problem.

Sponsored

 

[mangosmoothie]

my only guess from here would be an issue with wiring to the fpdm or to the pump. Checking voltage at the FPDM is easy enough. Not sure how you'd check pump voltage at WOT though.

I would probably start there to rule that out

 

[WildHorse]

Try a different sock ?

 

[KingKona]

Put a stock fuel pump in.

 

[KingKona]

How old is your battery?

 

[a10jay]

my only guess from here would be an issue with wiring to the fpdm or to the pump. Checking voltage at the FPDM is easy enough. Not sure how you'd check pump voltage at WOT though.

I would probably start there to rule that out

Fuel pump driver module was replaced and voltage at the FPDM and pump are good.

 

[a10jay]

Put a stock fuel pump in.

The low fuel pressure issue started with the stock fuel pump. That’s the only reason why I replaced it with a bigger pump.

 

[a10jay]

Try a different sock ?

Deatschwerks already supplies the correct sock for the specified fuel pump, DW400 w/ 1047 installation kit. It’s a perfect fit. I’ve even tried raising the fuel pump a little so that the sock isn’t possibly causing any restriction when sitting flat at the very bottom of the hat.

 

[a10jay]

How old is your battery?

Based off the datalogs my voltage is as good as ice cream on a hot summer day. The battery is perfectly fine. I couldn’t tell you how old it is I just know it’s doing it’s job.

 

[Andy13186]

Have you tried using any fuel system cleaning product or seafoam? Weird issue, will like to know the resolution.

 

[WildHorse]

Based off the datalogs my voltage is as good as ice cream on a hot summer day. The battery is perfectly fine. I couldn’t tell you how old it is I just know it’s doing it’s job.

Then it's a tune issue. Do they use this data ?

 

[a10jay]

Have you tried using any fuel system cleaning product or seafoam? Weird issue, will like to know the resolution.

Fuel injectors were tested and had no faults whatsoever during the process. Lund is saying it has nothing to do with Fuel Injectors. I’ve heard of 3-4 other people with similar issues. They either ignored it, blamed the tune, or still trying to find a solution.

 

[a10jay]

Then it's a tune issue. Do they use this data ?

Tuner is Lund. They actually have someone else dealing with the same problem and we are all trying to troubleshoot it. Being that they have tuned thousands of cars NA/Boosted equipped with DW400 pumps and have had no issues, I have a hard time believing it’s the tune.

 

[KingKona]

Based off the datalogs my voltage is as good as ice cream on a hot summer day. The battery is perfectly fine. I couldn’t tell you how old it is I just know it’s doing it’s job.

I'd take it somewhere where the really test it. Load test it. This sounds like an electrical issue, and these cars are extremely sensitive to batteries being the slightest bit out of spec.

 

[Soulja4187]

Toby had the same issue with the DW400, his buddy end up installing his E85 fuel pump and all issues went away. Check out this Video and fast forward to 30:20, he will talk about how the DW400 was giving him low fuel pressure at WOT

Sponsored