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21st March 2012, 13:16 | #21 | |
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Once the UBP looses it prime and stops, it will need quite a bit hgher a fuel level, to be able to reprime itself. So the best fix is to do away with the ITP and fit a pick up which reaches all the way to the bottom of the bottom of the pick up dish? I would really like to know what changes Rover made (if any) to the ITP system, which enabled them to do away with the UBP.
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21st March 2012, 13:21 | #22 |
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What a terrible design!! Another one in fact, as sadly there are quite a few ludicrous design items on our cars innit.. Makes one wonder if they were deliberate coz the Co was being sold.. ----
And I thought Jags idea of two separate pumps and tanks was mad!!!!!! ... |
21st March 2012, 15:50 | #23 | |
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TC |
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21st March 2012, 23:01 | #24 | |
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Who knows how long a new UBP would last running on its own? I do know I got at least 20k miles from my UBP running on its own. It had already covered over 100k miles and it was still going strong when I replaced it. Mike |
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21st March 2012, 23:18 | #25 | |
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It is a bit of a complex system for supplying fuel, but it is also regulating fuel temperatures, both ensuring a fast warm up and then stabilising the temperature of the fuel, and regulating the levels in both sides of the saddle tank. The more you look at it the more it ticks all the boxes. Shame they didn't build the pumps to last longer, as if they had the LP fuel supply wouldn't be a problem. There are recommendations never to run the tank below a quarter full even with both pumps running but I can't see a problem with it and I've nearly always run down to the low level light before refilling and had no issues. Mike Last edited by Mike Noc; 21st March 2012 at 23:29.. |
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22nd March 2012, 07:47 | #26 | |
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The 52PSI regulator, rather than a regulator, if that were instead an air release system, then it would make much more sense to me. We have already arrived at a conclusion that the ITP can start sucking air at below a quarter tank, which means some air will be pumped along with the fuel and the air would need to be released before the fuel is sent down the car to the UBP and HP pumps.
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Harry How To's and items I offer for free, or just to cover the cost of my expenses... http://www.the75andztclub.co.uk/foru...40#post1764540 Fix a poor handbrake; DIY ABS diagnostic unit; Loan of the spanner needed to change the CDT belts; free OBD diagnostics +MAF; Correct Bosch MAF cheap; DVB-T install in an ex-hi-line system; DD install with a HK amp; FBH servicing. I've taken a vow of poverty. To annoy me, send money. |
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22nd March 2012, 19:39 | #27 | |
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Of course the petrol pump delivers at 50psi on its own. TC |
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23rd March 2012, 07:39 | #28 |
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Agree TC both UBP and ITP have their own pressure relief valves, the UBP being external to the pump and the ITP built into it.
The pressure relief from the HP pump returns with the injector leakback fuel to the thermostatic valve for the heat exchanger. When the fuel is hot and the thermostatic valve is open it can vent to the tank, but with the fuel cold and the thermostatic vave closed the returning fuel joins the outlet from the fuel tank to return to the UBP. There is a restrictor in the line also going back to the tank but this looks like it vents off any oversupply from the ITP when it is only topping up the supply fuel when the thermostatic valve is closed. During this warm up period pressure could build up in this loop, so it makes sense to have a regulating valve in the circuit to relieve it if needs be. Mike |
23rd March 2012, 09:56 | #29 | |
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TC |
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23rd March 2012, 11:14 | #30 |
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What a valuable thread Great insights to be gleaned here and being new to diesel it has me intrigued as I've never heard of this Quarter Tank Syndrome and other than this thread and one regarding Dodge vehicles there is nothing more Google can offer me. Can someone elaborate as to where this term is derived from?
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