Diesel fuel pump failure or is it pressure regulator

Tiny
J.OILS
  • MEMBER
  • 1999 ROVER 75
  • 11,000 MILES
Car hick-cupped and eventually died. Fuel filter not full detected intank fuel filter pump, almost blocked with algae cleaned out, both low pressure pumps working ok but fuel pumping to common rail (with ignition on). No high pressure at c/rail when cranked. Not had any diagnostics report purely manualy tested. Can a failure be detected by bench testing manually in either the sensor or pump as I have now dismantelled
Tuesday, November 22nd, 2011 AT 2:06 PM

9 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
You should never remove anything till you pin point the failure.

If the low pressure pump failed. It starved fuel to the injector or high pressure pump. That alone will burn out the pump.

You said you replaced the lift pump and now have fuel to the injector pump? Then the injector pump most likely has failed.
Replace the pump. You wont get credit for the core unless you re assemble it.

Roy
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Tuesday, November 22nd, 2011 AT 2:15 PM
Tiny
J.OILS
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Without having the aid of computer diagnostics I carried out a manual test as discrbed earlier and found the resulting fault in the fuel tank but however this has obviously dry run the hpp or an electrical fault has occured to avoid damage.I have not replaced any components as of yet as there appears to be none visibly broken.
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Tuesday, November 22nd, 2011 AT 7:47 PM
Tiny
ASEMASTER6371
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You wont see the failure from visibly examining the pump. It is all about clearances and operations.

Roy
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Tuesday, November 22nd, 2011 AT 7:50 PM
Tiny
J.OILS
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The question really is, should fuel go to the c/rail via low pressure pump as it is meant to supply hpp with fuel, unless there is a fault at the hpp or could there be an electrical problem causing it? Ie. Hp sensor
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Tuesday, November 22nd, 2011 AT 8:12 PM
Tiny
ASEMASTER6371
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The low pressure pump feeds the high pressure pump which feeds the injectors.

It could be electrical but once again, the high pressure pump ran dry and most likely has damage internally.

What was the original failure and did you do electrical checks before taking everything apart.

Roy
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Tuesday, November 22nd, 2011 AT 8:27 PM
Tiny
J.OILS
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I disconnected the hp sensor to test for c/rail pressure under cranking (can this jam open)and also one by one all other sensors but no h/p. In c/rail at any stage which led me to believe a hpp problem had arisen because of the lack of lubrication from fuel.
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Tuesday, November 22nd, 2011 AT 8:54 PM
Tiny
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With the sensor disconnected, there will be no pressure.
Anyway, I agree that the pump is no good.

Roy
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Tuesday, November 22nd, 2011 AT 9:04 PM
Tiny
J.OILS
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Thanks for your evaluation. John
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Tuesday, November 22nd, 2011 AT 9:28 PM
Tiny
ASEMASTER6371
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Good luck

Roy
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Tuesday, November 22nd, 2011 AT 9:29 PM

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