rover 75 cdti high pressure pump

david2000 · 9th September 2019, 20:09

hi to all
I have a question about the high pressure pump
recently I changed the ubp as I have mentioned in previous threads now I tested the ubp and it had a pressure out put of 400 kpa the previous ubp had the out put of 250 kpa now this is my question if the ubp produces more than the max pressure of 440 kpa can this cause the o rings to fail in the high pressure pump the pump on my car has done over 100.000 miles and would be well worn
david

Mike Noc · 9th September 2019, 21:25

How did you test the UBP pressure David - was it still in circuit in the car? There is a pressure relief valve after the UBP, and if that fails then the fuel will just recirculate round the low pressure side.

As to blowing the O rings in the HP pump I can't see that happening given the differential pressure between the low and high pressure circuits. The pressure relief valve is more likely fitted to prevent damage to the UBP rather than the HP pump.

And your HP pump shouldn't be worn out at 100k miles - mine has just clocked up 400k and is still working fine.

As I mentioned in your other thread, check that the fuel pressure regulator is working correctly.

Brian and Russ found a problem with the voltage supply cable from Fuse 1 in the engine compartment fusebox - red wire with a white tracer. It supplies the glowplug relay, cam sensor, crank sensor, fuel pressure regulator, EGR and MAF. Failure of the supply would throw up multiple fault codes on your T4, but if the supply to the fuel pressure regulator, or the wire from the regulator back to the ECM failed, that could be your problem.

.

david2000 · 10th September 2019, 00:00

hi to all
I tested the voltage to the pressure regulator and it was 12v I shall try the other cable tomorrow weather per mating as for testing the ubp I connected a pressure tester between the ubp and the fuel filter turned on the ignition and read the reading then started the engine to see what the pressure was and it was over 4 bar
david

9th September 2019, 20:09	#1
david2000 Loves to post Rover 75 Tourer Join Date: Dec 2007 Location: Ammanford Posts: 485 Thanks: 248 Thanked 29 Times in 24 Posts	rover 75 cdti high pressure pump hi to all I have a question about the high pressure pump recently I changed the ubp as I have mentioned in previous threads now I tested the ubp and it had a pressure out put of 400 kpa the previous ubp had the out put of 250 kpa now this is my question if the ubp produces more than the max pressure of 440 kpa can this cause the o rings to fail in the high pressure pump the pump on my car has done over 100.000 miles and would be well worn david

9th September 2019, 21:25	#2
Mike Noc This is my second home Rover 75 CDT Manual Connoisseur SE, Rover 75 CDT Automatic Connoisseur SE & a Freelander Td4. Join Date: Jul 2009 Location: Hampshire Posts: 11,547 Thanks: 3,470 Thanked 3,119 Times in 2,247 Posts	How did you test the UBP pressure David - was it still in circuit in the car? There is a pressure relief valve after the UBP, and if that fails then the fuel will just recirculate round the low pressure side. As to blowing the O rings in the HP pump I can't see that happening given the differential pressure between the low and high pressure circuits. The pressure relief valve is more likely fitted to prevent damage to the UBP rather than the HP pump. And your HP pump shouldn't be worn out at 100k miles - mine has just clocked up 400k and is still working fine. As I mentioned in your other thread, check that the fuel pressure regulator is working correctly. Brian and Russ found a problem with the voltage supply cable from Fuse 1 in the engine compartment fusebox - red wire with a white tracer. It supplies the glowplug relay, cam sensor, crank sensor, fuel pressure regulator, EGR and MAF. Failure of the supply would throw up multiple fault codes on your T4, but if the supply to the fuel pressure regulator, or the wire from the regulator back to the ECM failed, that could be your problem. . Last edited by Mike Noc; 9th September 2019 at 21:41..

10th September 2019, 00:00	#3
david2000 Loves to post Rover 75 Tourer Join Date: Dec 2007 Location: Ammanford Posts: 485 Thanks: 248 Thanked 29 Times in 24 Posts	hi to all I tested the voltage to the pressure regulator and it was 12v I shall try the other cable tomorrow weather per mating as for testing the ubp I connected a pressure tester between the ubp and the fuel filter turned on the ignition and read the reading then started the engine to see what the pressure was and it was over 4 bar david