I've read various threads on here that says the LP fuel pump on the TD4, (under the rear wheel arch), should only run for a few seconds before switching off, when the ignition electrics are enabled. It would seem I have a problem with my fuel system, as mine runs for about 2 mins, before what I understand is the ECU shuts its off.

Ok, so I need to sort out why that is happening (changed the fuel regulator washer, and its still doing it, so leak back testing is next on the agenda - but that's something else).

My question is, what should the normal operation of the LP pump be when the engine is running? Is it supposed to run continuously along with the engine? Or is it supposed to stop, then let the high pressure pump take over syphoning the fuel needed from the tank lines? - If it's the former, I don't want risk burning out the pump motor, if it's only supposed to be on for a few seconds at a time, because mine seems to run continuous when the engine is running.

I've tried listening under the wheel arch and it sounds like the pump is running still? But not sure if that is just the noise of fuel being taken through the pump instead.

Any confirmation on what the pump is supposed to be doing when the engine runs would be much appreciated!

Many thanks

Jim

Is it supposed to run continuously along with the engine?

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i asked same at local LR dealership ..
techie said it runs all the time .. but goes into 'free wheeling' mode if fuel demand is low
something to do with a pressure relief valve ..
i can only hear mine running before the engine fires up ..
pump be quiet .. ( relatively new pump ) .. any other vehicle noise masks it ..

Thanks.
At least I know I'm not overrunning the pump, if it is supposed to be operational during normal use.
When the engine is running, it is really difficult to hear it, even with an ear under the wheel arch, but I could just about hear the faint noise, being masked by the TD4 rattle coming from the front of the car. So I'm hoping that there is a bit more life left in the pump (90k miles), before it dies on me, (which will probably the most inconvenient time, based on other people's stories).
Thank again,
Jim

So I'm hoping that there is a bit more life left in the pump (90k miles), before it dies on me, (which will probably the most inconvenient time, based on other people's stories).

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mine were changed @ 76k miles ..
symptom was the engine hitting a brick wall at 3000rpm regardless of which gear it were in
pump didn't get any noisier than when i bought the vehicle at 37k miles ..
( on second thoughts Maybe it were a tad louder )
fuel filter hadn't been changed either .. when the brick wall effect started to occur ..
( my fault as it should have been changed earlier )
so don't know if it were the pump or old filter that caused the issue .. 'cause changed the pump anyway due to mileage

other 'failing pump' symptoms include it getting much noisier
or needing a tap to get it to start working ..

when the pump or filter does need changing ..
not a bad idea to clean the whole mounting frame .. and give it a coat of some anti-rust paint
and .. smear some 'contralube-770' on the electrical plug/socket that runs the pump

replace the pump with the original Bosch type .. cheap alternatives wear out quicker ..
( the pump is sealed and cannot be rebuilt ..
( i think it's the electric motor bits that simply wear out ..

my new pump is about as loud as a modern small domestic refrigerator .. ( rough estimate )

I thought the best pump to use was/is the pierburg one ?

' john t' rekons both are used by LR
https://www.landyzone.co.uk/land-rover/and-so-my-fuel-pump-dies-on-my-td4.249163/#post-2944000
i'd use either ( my pierburg maf is doing well @ 66k miles )

It's not too noisy. Probably about the same level and sound as the noise the powerfold mirrors on a FL2 make, or an electric shaver. The engine running masks the pump sound.

To be honest, I never really noticed any sound until I became aware of the pump and its existence under the wheel arch when I changed the fuel filter. The cradle holding it was pretty rusty, so while it was off, I cleaned it up, got the loose stuff off and painted it with Hammerite to hopefully extend its life a bit more. Fingers crossed it will keep going for some time longer, which will give my wallet time to recover from the four new tyres about to go on, new VCU and bushes, and what's pointing towards an iffy injector problem, (the fact that pump runs so long on pre-ignition).

Thanks again,

Jim.

Mines loud! Like an unhappy bee or a mall electricity substation, its louder than the engine..

badfelafel said:

Mines loud! Like an unhappy bee or a mall electricity substation, its louder than the engine..

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under wheel arch /////// my pump started to go loud today turn the ignition on and very loud vibration and also can hear it with engine running . seen new cheap ones on ebay £25 may have a go at this price

having had problems with bad start when cold usually 2-3 cranks and refusal to start when warm unless left for some time
was advised to check lp fuel pump either fitted to tank or under wheel arch ,mine being tank figment was advised that the pump should run for up to a minute switch of retry after 30 seconds
and the time should be the same IN MY CASE(60 seconds) SO PUMP OK.
had injector checked 1 and 2 leak back high had reconditioned injectors fitted and freelander starts and runs like a dream
just to add the problem occurred after filling whith TESCO diesel instead of my normal bp octimax