anglefire
Member Since: 09 Mar 2010
Location: In the Club House
Posts: 4180
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I understood the LP pump, pumps fuel into the small reservoir and that is where the HP pump takes its supply - it is the same place that the FBH takes its supply from too - hence the ability to run when the engine is off. Mark.
2006, D3 SE Auto - gone but not forgotten.
2014 BMW 530d M Sport Tourer.
1977 Triumph Spitfire 1500
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Disco Picture Website Here
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 6th Jun 2011 6:25 pm |
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packingstrips
Member Since: 24 Mar 2010
Location: uk
Posts: 435
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Fuel burning heaters fuel is supplied by an auxillary pump mounted at the front chassis, its not part of the in tank fuel pump, however the fuel line does go in through the top of the intank pump.
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| 6th Jun 2011 6:57 pm |
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Adigorn
Member Since: 14 Mar 2010
Location: Birmingham
Posts: 546
  
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what a bull that LP pump is only for starting
failure of fuel tank unit will rather cause lack of power as well as engine will stall if intank pump will stop working
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| 6th Jun 2011 8:18 pm |
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packingstrips
Member Since: 24 Mar 2010
Location: uk
Posts: 435
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Adigorn.
How much pressure is in the low side when running?
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| 6th Jun 2011 10:01 pm |
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anglefire
Member Since: 09 Mar 2010
Location: In the Club House
Posts: 4180
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LP pump provides fuel at a regulated 0.5bar. The HP pump requires fuel at between -0.3 and 0.5bar. (gauge)
No where can I find a suggestion that the LP pump stops once the engine is started. The HP pump lifts the pressure to 1600bar - once the HP pump is running at 1500rpm (Not engine speed). At idle, the pressure is around 1500bar Mark.
2006, D3 SE Auto - gone but not forgotten.
2014 BMW 530d M Sport Tourer.
1977 Triumph Spitfire 1500
_________________________________________________
Disco Picture Website Here
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| 6th Jun 2011 10:39 pm |
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packingstrips
Member Since: 24 Mar 2010
Location: uk
Posts: 435
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-0.3 Bar?
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| 6th Jun 2011 10:53 pm |
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anglefire
Member Since: 09 Mar 2010
Location: In the Club House
Posts: 4180
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Yep, that is what the manual says - not forgetting its gauge pressure, so 0.7bar absolute.
It also says the HP pump returns the fuel to the tank at between -0.3 and 0.5bar. (Gauge) Mark.
2006, D3 SE Auto - gone but not forgotten.
2014 BMW 530d M Sport Tourer.
1977 Triumph Spitfire 1500
_________________________________________________
Disco Picture Website Here
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| 6th Jun 2011 11:12 pm |
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packingstrips
Member Since: 24 Mar 2010
Location: uk
Posts: 435
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Connect a conventional guage that will read zero at atmos, switch the ignition on and it will read around 0.5 bar or approx 7psi, start the engine and rev to approx 2000rpm, a negative pressure is noticed so whats going on there?
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| 6th Jun 2011 11:32 pm |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26705
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I suppose it depends where you connect the guage. If you connect it down stream of the fuel filter, and the HP pump is running at higher speeds, the pressure will be lower, possibly negative, if the filter is partly blocked.
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| 6th Jun 2011 11:45 pm |
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packingstrips
Member Since: 24 Mar 2010
Location: uk
Posts: 435
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No,at the engine Gareth with no blocked filters.
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| 6th Jun 2011 11:46 pm |
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Adigorn
Member Since: 14 Mar 2010
Location: Birmingham
Posts: 546
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ok gareth point taken sorry
Last edited by Adigorn on 7th Jun 2011 8:24 am. Edited 1 time in total
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| 7th Jun 2011 7:24 am |
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Gareth
Site Moderator
Member Since: 07 Dec 2004
Location: Bramhall
Posts: 26705
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I remember my old Citroen BX that I used to drive (a loooong time ago) and the fuel tank breather got blocked up. I was on a long motorway journey, when suddenly things started falling off from underneath the back of the car.
When I stopped and had a look, the fuel tank had been sucked into a collapsed heap of plastic. This was done by the sucking power of the engine powered diesel pump, and those cars were before the days of high pressure common rail technology!
@Adigorn, I don't see the need for the aggressive nature of your post's?
You have an opinion and thats great, but remember this is a discussion and not an argument 
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| 7th Jun 2011 8:10 am |
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Adrian L
Member Since: 24 Nov 2009
Location: Johannesburg
Posts: 35
 
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Hey. All
Thanks for all the input, its seems like its defiantly the HP pump thats the problem. Can't find a reconditioned part anywhere, tried three countries and they all say no stock.
Don't want to pay LR the full price (Although I may not have any choice.) any ideas on where to go from here?
Anyone got a spare one lying around? �I will go anywhere, as long as it be forward.� David Livingstone
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| 7th Jun 2011 11:59 am |
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packingstrips
Member Since: 24 Mar 2010
Location: uk
Posts: 435
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Gareth,Angel,Adigor.
Im going from my observations....there needs to be atleast 0.50 bar low fuel pressure to start the car, once running the pressure will decrease in the low line to a negative reading. If you look at description and operation you will see the hp pump creates enough to pull its own fuel through. Im using a guage that reads zero at atmos.....so if anyone has any ideas on whats happening i will only be pleased to hear it. From my observations the lp pump alone will not supply enough fuel to the hp pump at load and high rpm.
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| 7th Jun 2011 12:44 pm |
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anglefire
Member Since: 09 Mar 2010
Location: In the Club House
Posts: 4180
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The LP pump must be able to supply all the fuel for the HP pump surely - it has to be pulled through the pump by the HP pump otherwise. Just because it is low pressure, doesn't mean it's low volume. Mark.
2006, D3 SE Auto - gone but not forgotten.
2014 BMW 530d M Sport Tourer.
1977 Triumph Spitfire 1500
_________________________________________________
Disco Picture Website Here
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| 7th Jun 2011 9:41 pm |
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