MK3 (2013) diesel 1.6 - struggling to start and stay running

[Mike-Mike]

Hi all, I wonder if anyone else has had this issue and might be able to help identify?

The car was struggling to turnover when being started, then would start but run very lumpy and then stall. Eventually wouldn't start at all and I killed the battery trying. It had just under 1/4 of a tank of fuel in it.

Got it into the garage and they struggled to identify the cause - actually had it in twice. They changed the battery, cleaned the fuel lines and got it running. (They thought it might be the injectors, or the lift -?- pump but couldn't be sure and didn't to charge for and carry out unnecessary work and as it was then running they hoped that the issue had been cleared, and they advised to use good quality diesel and not to let the fuel tank go too low).

It ran fine for a few weeks - being used sparingly a couple of times per week for local runs.

Then it stood for two weeks whilst I was away and the issue has returned. It will just about start after a few attempts but again runs lumpy for a second or two and just dies. It has a 1/4 of a tank in it at the moment.

If anyone could shed any light it would be amazing as this is turning into a real pain. (It's done 111k miles).

Many thanks in advance.

ps - edit: I had the timing belt, oil and filter and fuel filter all changed in October 2022.

[unofix]

Has the fuel filter been replaced ?

When did it last have a new Air Filter ?

[TomsFocus]

Fairly sure this be air in the fuel lines.  Your car doesn't have a lift pump so it relies on a syphon effect to hold diesel in place when engine switched off.  Only takes a tiny hole to allow air into the fuel lines and the fuel will drain back to the tank.

[Mike-Mike]

1 minute ago, unofix said:

Has the fuel filter been replaced ?

When did it last have a new Air Filter ?

 

Yes, the fuel filter was replaced in Sept 2022.

Air filter was done as well at about the same time. I did notice the air filter box had one screw that was just spinning so the seal on that corner wasn't overly tight but the RAC man said that wasn't an issue.

[Mike-Mike]

2 minutes ago, TomsFocus said:

Fairly sure this be air in the fuel lines.  Your car doesn't have a lift pump so it relies on a syphon effect to hold diesel in place when engine switched off.  Only takes a tiny hole to allow air into the fuel lines and the fuel will drain back to the tank.

Thank you v much for the response.

So it could be a replacement of the fuel lines? Is that a big job do you know?

[TomsFocus]

4 minutes ago, Mike-Mike said:

Thank you v much for the response.

So it could be a replacement of the fuel lines? Is that a big job do you know?

No need to replace all the lines, just find the leaking part and replace that. 

However, these leaks are notoriously difficult to find.  There's not usually any diesel coming out to leave a visual clue.  Really have to look hard for any minor splits or pinholes around pipes and pipe connectors.

[Mike-Mike]

Just now, TomsFocus said:

No need to replace all the lines, just find the leaking part and replace that. 

However, these leaks are notoriously difficult to find, there's not usually any diesel coming out to leave a visual clue.  Really have to look hard for an minor splits or pinholes.

Thank you.

I'll suggest that to the garage.

(Odd that they were talking about a lift pump if the car doesn't have one - makes me think they're not on top of things, but they're an apparently reputable, busy place).

[TomsFocus]

4 minutes ago, Mike-Mike said:

(Odd that they were talking about a lift pump if the car doesn't have one - makes me think they're not on top of things, but they're an apparently reputable, busy place).

Most modern diesels do have a lift pump.  Ford have to be awkward...   A few years later, when the 1.5 TDCI replaced the 1.6, they did use lift pumps.

[Mike-Mike]

1 hour ago, TomsFocus said:

Most modern diesels do have a lift pump.  Ford have to be awkward...   A few years later, when the 1.5 TDCI replaced the 1.6, they did use lift pumps.

Ah, got it... an understandable misconception then.

[andypsp]

9 hours ago, Mike-Mike said:

 

Yes, the fuel filter was replaced in Sept 2022.

Air filter was done as well at about the same time. I did notice the air filter box had one screw that was just spinning so the seal on that corner wasn't overly tight but the RAC man said that wasn't an issue.

was it running ok before you had the fuel-filter replaced last year ?

[Mike-Mike]

18 hours ago, andypsp said:

was it running ok before you had the fuel-filter replaced last year ?

Yes, tbh I hadn't done that many miles before the service, and I'd done several hundreds since the service before any problems cropped up.

I did wonder whether the service did more harm than good!

[Mike-Mike]

Just in case it's useful for anyone else - this turned out to be the fuel pressure regulator.

Cheap-ish part, expensive to fit.

I've done a good few hundred miles, short and long journeys since it was fitted and it's been fine, so far.

Fingers crossed that'll be it for a while.

Thanks all for the suggestions.