[Dancingdad]

Put some logic to it.
An HP pump either works or it does not.
It doesn't intermittently fail and then work !

Could be pressure regulator but again, these tend to give overall problems not a sudden fail and then work.

Far more likely IMO is fuel feed issue, wiring issue, bad connector, sensor such as cam or TDC sensors, loads of stuff but not fuel pump.

Give us some more information please.
Any diagnostic codes?
And tell your mechanic to leave the pump alone unless they can prove this is the fault.

 

[Dancingdad]

Tom
I am even more convinced now that any work your mechanic is doing on your fuel system is a waste of time and money.
Certainly does not warrant a pump change without full investigation.

The dash lighting up and low pressure error can all be because the engine stopped, not the cause of stopping.

The real issue could be many things.
Favourites would be TDC (crank sensor), easy to pull out and clean, they can collect gunge and stop working.
Not overly expensive to replace.

Could be fuel issues such as fuel filter clogged or a leaky injector, both likely to show more at low revs then high. And to be fair, could be fuel regulator.

Could be wiring issues, not sure if the Movano has it but Trafics have a blue plug in the fuse box that is notorious.

I'd be asking your mechanic to stop guessing at your expense and do some proper tests.
Live data when engine running will give more clues then reliance on codes that are not being shown or could be because of the problem.
A leak off test will show if injectors are suspect.

If you and them decide to swap bits just in case, pick the likely ones that don't involve a large amount of money.

 

[Dancingdad]

Tom
We obviously do not have the full story.
Which is not knocking you as I suspect neither do you.

But everything you say is screaming at me that they are scrabbling around in the dark.

From what you say the motor will run but drops out.
Intermittent fault, which are the most difficult to find.
The diagnostic code that comes up is Fuel Pressure.
That is most likely a result of the engine stopping and the rail sensor is reporting a true fact, engine stopped so pressure dropped.
Not pressure dropped so engine stopped.

They can check the fuel rail pressure on live data with the engine running.
That will tell anyone who knows what they are doing whether pump or pressure system is doing what is expected.
Only if it isn't do parts get swapped but not before other simple and relatively cheap tests are carried out.
Like an injector leak off test.
Like a fuel sample and check for contamination
Like replacing the fuel filter and checking the old for contamination.


Don't know what to suggest for the best except I would be saying enough and getting the van out to someone who knows what they are doing.

 

[Dancingdad]

I may be being unfair to your mechanic.
But no one can condemn a diesel HP pump without some checks.
And although tinternet is awash with tales of pump failure, almost invariably this is that the pump has eaten itself.
Considering the number of DCi diesels out there, failure rate is relatively few, for every one that is reported failed, there are probably in excess of thousands, tens of thousands even, still happily chugging away.

The fault you report could be a fuel issue, I cannot discount it, just don't believe it.
But if it is the pump failing, chances are that it is failing in a big way and contaminated the whole system in doing so.
Swap out the pump and next month the new one will fail. So will the injectors if they already haven't.

You may not want to hear if the pump has failed like that or that it requires a full system clean and replace that could cost thousands but if that is the case, you don't want to spend 400 quid this month for it to fail again next month either.

Simple tests will show issues or discount them.
If a garage is not using these tests or not willing to try them, they are ripping you off.


We often gripe about Renault Dealers not willing to investigate anything without a full diagnostic (at a high cost) but there is some logic to it.

 

[Dancingdad]

..........Playing parts darts is a very expensive hobby, especially when its someone else's money..

Actually very cheap when it is someone else's money :wink2:

 

[Dancingdad]

I certainly would not be happy leaving the van with them.

As Ourkid says, proper diagnostics with someone who not only can use the machine but also think what the results mean can be invaluable.
With someone who is simply reading error codes it is easy to go astray.
The computer says no is not a comedy when it happens.

And while I have a lot of faith in mechanics who can tell what is happening or not by listening and understanding an engine, I have not got enough faith to let them change a fuel pump or any other expensive part without something more positve.

 

[Dancingdad]

Glad you got it sorted, even if it was a nightmare.
And yes, not saying any mechanic will be right or wrong but at least with one you trust and who is fair, you stand a chance.