Common fuel pressure issue?

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Wrstewart

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This has been discussed before but each time it seems like there are different symptoms and fixes. I thought I would add mine to the list in case anyone has a similar experience.

Wife was driving the 2012 V8 LR4 HSE Lux, calls me to say “your car just did something weird”. Poor acceleration and “Restricted Performance” warning on dash. I started it up a little while after she got home and it took a while to crank but settled into a normal idle and ran fine in the driveway. I plug in the SDD to diagnose. I pull the P0087-00 code which the manual reads as “Fuel Rail/System Pressure - Too Low”. Several of the possible causes revolve around the fuel rail pressure sensor so I ordered one from FCP Euro with rush shipping. A lot of threads on here mention the HPFP but the logs say my pressure is at like .068 PSI. At that level it would probably be impossible for the car to even run, and definitely throw some misfire codes. Im really hoping it’s just the sensor.

After dinner I went back out and started it up. It was very erratic and would bounce between 200 and 1200 rpm and immediately die. I plugged the SDD in again and now it’s reading:
P00C6-00
Fuel Rail Pressure Too Low
- Engine Cranking - No sub
type information.

The manual says it’s likely the HPFP.

While researching this some threads suggested using BG 44k in the tank to clean the fuel system. I picked up a can from the dealer for $26 and dumped it in my already full tank. At this point I wasn’t sure how it would even get to the fuel system through a whole tank of gas, especially if the truck won’t even run. I had the brilliant idea to give it some gas on startup and after some struggle it ended up running and idling again just fine. I left it running for about 30 minutes to try to get some of the fuel treatment to the pumps, sensors, and injectors. When I shut it down and started it back up, I didn’t have to give it any gas, and it settled into idle without any drama.

I don’t think the 44K has had enough time to do much of anything, I’m attributing the better performance to the engine being warm, although holding out hope for it doing something.

That’s all I have for now but I’ll let you know how it goes once I put in the new sensor.

-RS
 

powershift

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With it running fine it will be hard to determine if the new sensor fixes it. My service history (same year as yours) shows the fuel pump was replaced at 91k mi. How many miles does yours have on it? I'd be replacing it regardless of the sensor results.
 

Wrstewart

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I have about 140,000 on it, not sure if the pumps have ever been replaced. Another member on here said something about the pumps never actually going bad, just needing the fuel treatment to get them working efficiently. In your opinion is there a service life for the pumps? Why replace the pumps if the sensor fixes the issue?

When I do the sensor I will hook up an external fuel pressure gauge and see what the actual pressure is on startup and idle. I don’t think the ECU is getting the correct value.
 

powershift

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When I was shopping for an LR4 looking at service records, there were fuel pump replacement records. 140k miles on it is pretty good i think. I'm not an expert in this area but for me I'd want to do the preventative maintenance and change the fuel filter too. If you are more of a reactive person then wait for it to fail and then replace it.
 

L Crist

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I've had this very same issue on my 2011 LR4. Very long story short-- We tried the Seafoam first to no avail. Finally had the hpfp's and the lpfp replaced and voila. No more misfires.
 

jlglr4

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Wonder if it could be the low pressure fuel pump relay cutting in and out. In any event, I’d suspect the lp pump over the hpfps with it cutting in and out like it seems to be doing based on the initial post.
 

Wrstewart

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I think they replaced the low pressure pump during the flange recall. I also swapped the blower relay and the fuel pump relay, the blower still worked and the fuel problem persisted. I have the fuel rail pressure sensor, I’ll replace that tonight. Does anyone know how to bleed the lines after install? I can’t find a Schrader valve anywhere. I’m guessing they don’t use them on high pressure systems.
 

Wrstewart

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Couldn’t wait for an answer… Got the new sensor in, even though the old sensor looked pretty filled with junk, the new sensor did not fix the problem. I have a new low pressure sensor too. Maybe I’ll put that in and see what happens.

IMG_3296.jpeg

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