Disco 1 Fuel pump, Fuel pressure Regulator problems.

Hi All,
It's been a while as I have not done much work starting up the V8.
Work done in last 6 months (could be more!), taken off old downpipes with cats to replace the lambda sensors.
Snapped a stud in the exhaust manifold, took that off - bit nervous would snap studs but they came out great, had the manifold repaired.
I thought while the down pipes were off I would just replace with a new ones, fitted new lambdas, fitted downpipes and jerry rigged up the exhaust system.
OK its started no problem but the engine management light flashing again.
Rigged up my ECU mate and cleared faults, the engine began to run smoother, and management light went out, put some fresh petrol in the tank.
OK left the car for around 1/2 hour came back and engine management light flashing like a good un again before I had started the engine, I could hear the fuel pump still pumping/priming started the engine and it was as rough as old boots and strong smell of petrol with EML flashing but it slowly cleared itself up and ran smooth and tick over very even.
Today came out to see if fuel pump would shut off when I turned the key (no start up yet) EML flashing and fuel pump priming, clicking noise coming from the fuel pressure regulator.
After all that blather I think the fuel pressure regulator is faulty?

Any input would be grateful before I order a new one.

Cheers Ian

Very strange, I never heard my regulator make a sound much the same as the fuel pump, the regulator is a basic mechanical valve operated by vacuum from the plenum chamber, basically if the fuel pressure exceeds the spec. the valve operates and petrol is returned back to the tank. Simples and effective.
The vacuum pipe is ok and connected ?? As for the other issues I haven’t a clue, it’s something I’ve come across, fortunately.

Thanks for reply Discool,
OK should the fuel pump shut off when primed or does it continue to pump?
Its a difficult one to try and write down.

IandiscoV8 said:

Thanks for reply Discool,
OK should the fuel pump shut off when primed or does it continue to pump?
Its a difficult one to try and write down.

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Shut off, and then restart pumping on cranking of the engine.

Its not shutting off, i am more familiar with motorcycles and they prime up and **** off until needed, when i turn the key pump continues to run

Well the EFI ECU controls the fuel pump via the fuel pump relay, so either could be iffy and would have the pump running continuously, maybe rare for the ECU so it’s more likely the relay is locked on... that’s just a guess of course as there isn’t anything else.





Sent from my iPad on a train

OK tried the V8 again this evening, again rough as when first starting and EML flashing, read a post on here about earthing out the Fuel pump relay, no clicking noise now.
Disconnected the fly lead and it started on bother with a very steady tick over, shut it off and I could hear the fuel pump had stopped with ignition on, started up without a problem a few times.
Ordered a new relay for the fuel pump, fingers crossed!
Thanks for the help

Just went to lock up, thought I would try it again, looked for the 'clicking noise' it is coming from the fuel pump relay

Ian

Hi Discool,
Update, changed the fuel pump relay and its doing the same thing/symptoms.
Basically the pump is running continuously, EML flashing, fuel pump relay clicking and fuel regulator clicking away before I start it up from cold.
When I start it up and it does start no bother it is as rough as a badgers a...se and really stinks of neat petrol; runs like that for around a minute to minute and a half it clears up and ticks over no bother, starts restarts no bother with no symptoms, fuel pump is switching off with the ignition on.
Leave it a while and symptoms return, fuel pump runs continuously and runs crap for little bit and clears up.
Is there a cold start mechanism on these V8's

I would be happy if some one could lend me a fuel regulator and an ECU and that would take them out the loop;

Ian

Ok, so how did I test the existing relay as it seems it wasn’t faulty, what was the part number of the replacement? With the ignition off remove the relay does the pump still run when its turned back on? Also you sure it’s the fuel regulator that clicking as the no electrical supply to it and so if the engine isn’t running it’s doing anything.

Straight forward replacement relay, used the correct numbers.
Yes I agree with you about the fuel regulator - it should not 'click' I think it is the fuel pump pulsing but the relay is definitely clicking.
I just cannot figure out why its working ok after a short time running and running ok afterwards for a while.
I will go and take the relay out and see if the pump runs

Cheers

There’s two 12v supply’s to the fuel relay, are they both reaching the relay. Diagram below shows what is what and the two fuses involved.

OK appreciate the input, I do have the manual so not working blind as such, OK i have an anomaly which is good, there is a bypass wire going to the purge valve, I have tried wiring the old white and purple but nothing happening - the alarm just comes in eventually, reconnect the bypass and same results, iit runs bad then settles.
The bypass wire is definitely the thin white and purple to the purge valve.

cannot find a purge valve in the manual, I will do 12v tests to the relay tomorrow

OK found the purge valve and on the vehicle, no bypass up to the valve, must be going somewhere else.
Maybe someone bypassed the valve, can this be done?

IandiscoV8 said:

OK found the purge valve and on the vehicle, no bypass up to the valve, must be going somewhere else.
Maybe someone bypassed the valve, can this be done?

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Don’t worry about the purge valve, that is on top of the round charcoal canister that’s positioned on the offside inner wing, the purpose is to purge the fuel tank of fumes and direct them into the inlet manifold.
The canister can be removed, isolated, Land Rover recommendation is replace the canister every ten years, can’t say I’ve seen or heard of anyone doing that.

OK cheers, I will do some electrical measurements at the fuel pump relay later this evening

Ian

Well I have made progress and its by accident really.
I had a feeling the ECU was at fault, took it out and contacts looked OK, put it back in and moved it and the wiring around and the clicking slowed down, pushed on the ECU connector and its stopped the clicking at the relay and the fuel pump stopped priming.
I guess a quick clean up of the ECU contacts should cure it.
Thanks for the input Discool

Ian

Discool, I thought it was fixed with the pressure on the ECU clamp - nope.
So I found a reasonably priced used ECU, changed it for mine hey presto all fixed, started it a few times so it would get calibrated, small adjustment with the ECU mate and its now sweet as a nut.

Thanks for the input
Ian

IandiscoV8 said:

Discool, I thought it was fixed with the pressure on the ECU clamp - nope.
So I found a reasonably priced used ECU, changed it for mine hey presto all fixed, started it a few times so it would get calibrated, small adjustment with the ECU mate and its now sweet as a nut.

Thanks for the input
Ian

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Finally So well done, but you was unlucky as the Ecu, are normally fault free ie not the first suspect.

Saying that my old RR Ecu failed, but there’s was an issue known by LR with some of them and I had one confirmed by my main dealer with swapping the part over with one from another customers RR, that’s was the only way then, sadly a new replacement was out of stock and there’s was a waiting list, so I removed the ECU and took it to Lucas, I took the day off and drove up to Lichfield to the big Lucas repair centre, they easy found the fault and install updated parts while i waited so better than it was when new.