Hello,

2019 LR5 HSE Luxury SCV6 Gas. 39600 miles.

I’m having the low fuel pressure issue and already replaced low pressure fuel pump, fuel control module O2 sensors, Fuel Pressure sensor on fuel rail.

still when I turn on the car, low pressure pump is at 10-30psi I turn off, back on, off again and back on 3 times or so and the pressure goes up to desired pressure on GapIID tool.
desperately annoying how hard it’s been to fix this. Seems everyone ends up not fixing or finds different ways.
attached are the codes and live monitoring screens from Gap tool. Any ideas would be great. Thank you all.




Maybe that fuel rail temperature sensor makes gut be the culprit now but seems it was not the case before.

 

I don't know much about the SDV6, but here's what the service manual says about those two codes. It doesn't look like there's much to the low pressure fuel system. Fuel pump, pump driver module, and the pressure sensor prior to the high-pressure pump. Either the driver is bad/disconnected from the pump, the pump is bad (but you replaced it), the internal hoses in the tank are leaking (usually fully replaced with the pump), or the pressure sensor is bad (but also replaced). I'd be looking for a wiring issue or driver module issue.

 

Thank you Chuck.
I’ll explore those suggestions.
such an odd thing.
example. I started the car and pumps are matching the desired PSI. I drive a few miles and suddenly low pressure pump shows 10ish PSI vs desired 80psi. Car dies. I give it a min start again. Drive and no more issues while driving. Desired and displayed PSI all match…
so frustrating…

 

Fuel FILTER?

 

the fuel pump module would be next on my list. Modern EFI systems monotor the fuel pressure and the pump module varies the pump drive to keep it in parameters.

 

So far I replaced:
fuel pump inside tank: done by mechanic and got ripped off btw. Said ordered genuine, charged me $$1000 and from the picture you can see it is not a genuine oem
high pressure rail fuel sensor (LR108241

low pressure fuel sensor (LR082759)
fuel pump control module
pcv valve.
fuel tube going trim top of fuel pump. (LR082728) Waiting for it to arrive because it does not seem to be locking in well.
Relay and fuse are good.

lesson is to start by looking at leaks on the line before replacing things. But my amateur self kept getting sucked in to replacing parts Tuition of life.
I’ll try testing the pressure for a leak closest to the tank and go from there.
seems to be getting better but not sure why
picture

picture of the hose I ordered to replace next. The one on the right.

 

I highly doubt the hose outside the tank is leaking. If it were, the fire department would have already paid you a visit and you'd have different pics to show.

The pressure should be measured independent of the truck's LP pressure sensor to rule out the non-genuine pump. This is a separate issue altogether. Personally I'd insist the mechanic resolve this if OEM was promised.

I keep going back to P025A-13. If this code is cleared and keeps coming back then the fuel pump module is defective or the wiring between the fpm and the pcm are likely damaged. There's a yellow with orange wire that is used to control the fuel pump driver. The PCM may be detecting no load on that wire or when it changes the PWM frequency it doesn't detect an equivalent change in fuel pressure. There's also a high-pressure relief valve in the fuel pump module in the tank. Sometimes that can stick open and prevent proper pressure delivery. I've had this happen in one of my other cars. The fact that your original pump and the new "suspect" pump both have similar symptoms is suspicious to me though. I'd still be looking at electrical.

It's also possible the fuel pump control module fuse is blown if your original pump truly failed. I believe it's fuse 46 in the rear fuse panel. Maybe fuse #2? Check the diagram in your owners manual and relay box. Some of what I'm finding is inconsistent.

 

It's also worth pointing out that many fuel-related systems are covered by an 8 year 80,000 mile federally mandated warranty.

Disregard the highlighted bits. They're from a PDF I found on the forum. Pretty much everything related to fueling the engine should be covered by the dealer.

 

One last thing and I'm out of ideas for you. Have your main battery checked. If the battery is worn out you may have an excess voltage drop during cranking that could cause all sorts of issues.

 

Thank you on all the suggestions Chuck. I’ll start looking g into the integrity of the wires now. I’m not good with electrical work but this is a good way to start learning.
if it goes nowhere I’ll look into the 8yr coverage.
im at 39600 miles.

my guess is it must be electrical issue because I’ll try starting and it won’t start for 3 or 4 times and pressure stock at 1.3psi or so, then all of a sudden I try again and I see the pressure quickly climb to the 7psi desired and then it keeps adjusting and matching desired thereafter. Odd.