Fault Codes U2023 and P0087

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Originally Posted by Rsys

One weird thing I have. If I pull the LPFP fuse, the LPFP still runs. Figure that one out. I’ve concluded that on a disco 3, nothing is as it seems

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That is indeed peculiar. If I pull the LPFP fuse the car still runs, but that's relying on the feed pump in the HPFP to pull fuel up from the tank. The LPFP is certainly not running.

I wonder where it's getting power from, and if it's a reliable circuit?

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Originally Posted by BradC

That is indeed peculiar. If I pull the LPFP fuse the car still runs, but that's relying on the feed pump in the HPFP to pull fuel up from the tank. The LPFP is certainly not running.

I wonder where it's getting power from, and if it's a reliable circuit?

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That’s the only thing stopping me from replacing the HPFP. Where is the LPFP power coming from? If I take the fuse out and put the ignition on I can hear the pump run for the 15 seconds. It suggests a short somewhere and as you say, it may be not be a reliable circuit tripping out occasionally.

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Originally Posted by Rsys

Lol. Unfortunately mine is an auto and the BING coincides with TRANSMISSION FAULT So it’s too late. However, having read this thread a couple of months back, I’ve been driving by taking my foot off the gas where I think it would normally fault like a shallow incline.
I would think a leaking injector should throw a Low Injector Pressure fault and not the fuel rail. Who knows? It’s a disco!

My rebuild happened after the dreaded oil pump failure.

One weird thing I have. If I pull the LPFP fuse, the LPFP still runs. Figure that one out. I’ve concluded that on a disco 3, nothing is as it seems

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Why do you think it’s still running? Because it keeps running? Refer to Brads comment that the HPFP can successfully draw through it, albeit not effectively.

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Originally Posted by DiscoJeffster

Why do you think it’s still running? Because it keeps running? Refer to Brads comment that the HPFP can successfully draw through it, albeit not effectively.

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Sorry. Extra explanation. If I pull the fuse, then put the ignition on I can hear the pump run for it’s 15 seconds before the relay kicks it off. If I replace the fuse, exactly the same. So the relay is getting power from somewhere but it doesn’t look like it’s from fuse 1. Which is why I am so baffled.

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Originally Posted by Rsys

Sorry. Extra explanation. If I pull the fuse, then put the ignition on I can hear the pump run for it’s 15 seconds before the relay kicks it off. If I replace the fuse, exactly the same. So the relay is getting power from somewhere but it doesn’t look like it’s from fuse 1. Which is why I am so baffled.

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I’d certainly be looking into that. Unfortunately unless your P0087 occurs under heavy load then it’s unlikely the Power source to the LPFP is the issue.

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Originally Posted by BradC

I’d certainly be looking into that. Unfortunately unless your P0087 occurs under heavy load then it’s unlikely the Power source to the LPFP is the issue.

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No. Mine is under normal driving usually either on the flat or slight incline. Boot it and it’s fine. I’m certain it’s the HPFP but before the rebuild it was fine so something happened during the rebuild - either some dirt ingress or damage in some way

The rebuild was a total abortion by the garage. Leak off pipes leaking onto the exhaust (that was a fun journey). Both rockers leaking. Servo pump seal leaking. I even told them to blank off the EGRs (which had been software deleted) and that wasn’t done.

I’m loath to get rid of the car because so much of it is as new now.

I’m actually in the U.K. and used to run a pub right next to Britpart and know some of the management from those days. The reason I came across this forum was that the symptoms matched mine exactly ie none of this brake switch stuff.