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Marcus97



Member Since: 14 Dec 2024
Location: Montreal
Posts: 69

Canada 2010 LR2 i6 HSE Auto Stornoway Grey
Fuel Pressure at 0 PSI with Engine off?

Hi all,

As the title suggests, my fuel pressure is at 0 PSI with the engine off, according to my newly-bought OBD2 scanner.

Now I just want to make sure I'm not misinterpreting this reading.

Does this confirm I have a leak in the fuel line, or is this simply explained by the fact that "some ECUs only report live sensor values when the pump is commanded on (engine running or during priming)."

Thanks in advance!

Post #451093 17th Aug 2025 3:39 pm
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BossBob



Member Since: 30 Sep 2010
Location: Bristol
Posts: 1509

England 2007 Freelander 2 TD4 GS Manual Baltic Blue

If the engine isn’t running the fuel pressure is going to be zero because pump in the tank only supplies the swirl pot in the fuel tank. The mechanically driven fuel pump that sucks fuel from the tank (low pressure) via the filter and supplies the fuel rail (high pressure) is driven by one of the cam shafts.

Post #451098 17th Aug 2025 8:21 pm
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Marcus97



Member Since: 14 Dec 2024
Location: Montreal
Posts: 69

Canada 2010 LR2 i6 HSE Auto Stornoway Grey

This is for the petrol engine which I don't think has a high pressure fuel pump.

This reading of 0 PSI comes from the fuel pressure sensor on the fuel rail, correct? So it should be registering residual pressure if it is registering anything?


Last edited by Marcus97 on 17th Aug 2025 10:43 pm. Edited 1 time in total

Post #451099 17th Aug 2025 8:27 pm
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OxonPete



Member Since: 11 Jun 2024
Location: 11350 France
Posts: 239

England 2012 Freelander 2 SD4 HSE Lux Auto Santorini Black

Is car running ok……? Are you just checking with your new code reader….?

I wouldn’t have expected to read pressure in fuel rail when engine not running…..but I am not familiar with the 3.2 petrol……….
But p_gill knows a lot about the 3.2petrol…….he will know I am fairly sure……
But if car is running ok…..don’t worry…. FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

Post #451100 17th Aug 2025 9:07 pm
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Marcus97



Member Since: 14 Dec 2024
Location: Montreal
Posts: 69

Canada 2010 LR2 i6 HSE Auto Stornoway Grey

The car runs fine, but I've been attempting to remedy the loooong crank times I've had with this vehicle since I bought it in December. Everything points to a leaking check valve in the fuel pump.

Post #451101 17th Aug 2025 9:12 pm
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OxonPete



Member Since: 11 Jun 2024
Location: 11350 France
Posts: 239

England 2012 Freelander 2 SD4 HSE Lux Auto Santorini Black

Sounds feasible…..if the fuel is running back to the tank when engine is off…..
Don’t know if changing the check valve is expensive ….or complicated…if not then that’s the way to go……

Nice to hear p_gill’s view……. FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

Post #451102 17th Aug 2025 9:17 pm
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Marcus97



Member Since: 14 Dec 2024
Location: Montreal
Posts: 69

Canada 2010 LR2 i6 HSE Auto Stornoway Grey

I'm pretty sure it requires changing the whole fuel pump. But if I can confirm that the issue is indeed the check valve (nothing serious), I'll have the peace of mind and just ignore the long crank time.

Last edited by Marcus97 on 17th Aug 2025 10:45 pm. Edited 1 time in total

Post #451103 17th Aug 2025 9:24 pm
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OxonPete



Member Since: 11 Jun 2024
Location: 11350 France
Posts: 239

England 2012 Freelander 2 SD4 HSE Lux Auto Santorini Black

I imagine that will be expensive……….there must be some test to check the pump…perhaps needing to remove the pump for bench testing………….you could do with contacting someone who really knows about these machines……..! FL2 SD4 HSE Lux Auto MY 2012— current
D2 TD5 HSE Man MY 1999 470kmls….gone 2014 ….lovely engine..chassis rotten
D1 300TDI Man MY 1996 56kmls….gone 1999…D2 much better
Wife’s FL1 1.8P MY 2001 32kmls …gone 2007…has Mini since.

Post #451104 17th Aug 2025 9:47 pm
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p_gill



Member Since: 06 Dec 2011
Location: USA
Posts: 1320

United States 2008 Freelander 2 i6 SE Auto Tambora Flame

Pete and Marcus,

Thanks for the vote of confidence.

Here is my two pence worth.

Back in the day I owned a 535i with a faulty check valve and I was able to get a replacement valve and install it in the fuel line. It worked for a while but ultimately I had to replace the pump.

I’m not sure if the 3.2 has a good place to install a check valve.


As for the measurement of the pressure using a ODB2 tool with the engine off.

I have made this measurement but you have to be in the correct power mode.

My memory says that the mode that will allow you to switch the automatic transmission to neutral is the correct one.

Let’s assume that we are in the correct power mode

Then I would check the pressure right after switching off the engine and assuming the engine is hot the pressure should rise slightly and if it drops like a stone then look into a check valve or fuel pump

Note: I wouldn’t expect the fuel line to retain pressure for several hours. The check valve on my LR2 will leak down overnight.

Good luck

Paul

Post #451127 18th Aug 2025 9:04 pm
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Marcus97



Member Since: 14 Dec 2024
Location: Montreal
Posts: 69

Canada 2010 LR2 i6 HSE Auto Stornoway Grey

Your two pence worth is always appreciated!

These reading were taken in Mode II (aka, I held down the start/stop button for 2s without touching the brake). Reading was 0 PSI irrespective of whether the vehicle had been left overnight or had been running seconds before.

I think a mechanical fuel gauge would be necessary to confirm that this isn't just a false reading from a sensor that isn't actually reporting anything. But that seems to be quite complicated to connect to the fuel line...so I guess I'll just ignore this for now.

Thanks all!

Post #451129 18th Aug 2025 9:44 pm
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p_gill



Member Since: 06 Dec 2011
Location: USA
Posts: 1320

United States 2008 Freelander 2 i6 SE Auto Tambora Flame

Marcus,

If you really want to know that the pressure is ZERO you could remove the fuel pressure sensor.

When I changed mine I had some pressure in the line and it sprayed fuel at me but I used a rag to catch the fuel.


Or you could do what Volvo recommends to drop the fuel pressure.

First run the engine

Then shut off

Remove the fuse for the fuel pump and start the engine and it will stall due to fuel starvation

In your case if the pressure is actually zero then it would wouldn’t run for even a few seconds


This is actually a good way to check for fuel pressure indirectly


Good luck

Paul

Post #451197 20th Aug 2025 3:54 pm
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Marcus97



Member Since: 14 Dec 2024
Location: Montreal
Posts: 69

Canada 2010 LR2 i6 HSE Auto Stornoway Grey

p_gill wrote:
In your case if the pressure is actually zero then it would wouldn’t run for even a few seconds


I finally had a chance to try out your Volvo recommendation, and the car wouldn't run for even a few seconds. I just cranked away and gave-up after maybe 5s.

That said, it is apparently normal for the pressure to be 0 PSI before starting the engine, according to this: https://www.freel2.com/forum/post450622.html

It would be interesting to know if anyone can actually get their car to start with the fuel pump fuse pulled-out. If not, then there's little doubt my fuel pump's check valve is compromised. Not sure it's worth replacing the whole pump ($500+) just for that, though.

I also noticed my starting trouble actually manifest in two different ways. There's:
1) the longer than normal cranking when the vehicle hasn't been driven in awhile. However once the vehicle starts after that long crank, it will start immediately during subsequent attempts.
2) The vehicle cranking and starting, but then stalling. This happens when the engine is hot. I'm betting this is due to a "heat soak" of the camshaft sensors as seen here: https://www.landyzone.co.uk/land-rover/sol...st-5877032

Bought new cam sensor from rockauto, will update you once installed.

Post #451309 25th Aug 2025 9:24 pm
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