Another D40 P0093 code question.

[Marked]

Been struggling with a P0093 error and limp mode on cold start for quite some time.
Replaced pressure relief valve some months ago which seemed to settle it for a while, but now the weather is colder it has raised its head once more.
Threw some injector cleaner in it a week or two ago and it ran fine until today, when before the injector cleaner it had been playing up on every single start.
Checking fuel pressure via obd, I note a very speedy bleed off of pressure on turning engine off (5-10 seconds max) - I was under the impression it should take some time for the pressure to bleed off? Does this indicate anything in particular to tackle next?
If I understand correctly, the prime possibilities as to cause are; sticky/dirty injector, fuel pressure sensor, injector seals?
Engine oil level is not being affected.

What should I be looking at next?

Cheers.

 

[Marked]

Fuel Suction Control Valve?

 

[Old.Tony]

It's possibly the SCV, but that usually presents as a problem when accelerating hard and not during cold starts.

It's possible that there's a small leak in the fuel line. You won't see diesel coming out because the fuel system is a low pressure one up to the pump. This would allow air into the system while the car is resting and naturally presents as cold-start difficulties.

The way to find this is to pop the bonnet and pump the primer. It should only take 4 to 5 squeezes to go firm - but don't stop there. Keep going for another 10-15 squeezes and you should see diesel coming out of the leak.

If it is leaking, it may take more than 4-5 squeezes to get it firm too, so if you're on your 6th or 7th squeeze and it's still soft then you may have found the culprit. And I don't think I could use that phrasing anywhere else either!

 

[Marked]

Have replaced scv ... faster fire when starting, more responsive throttle and higher baseline fuel pressure, but has still gone into limp on one cold start since. Stop and restart solved. Will check fuel lines this weekend.

 

[Marked]

It's possibly the SCV, but that usually presents as a problem when accelerating hard and not during cold starts.

It's possible that there's a small leak in the fuel line. You won't see diesel coming out because the fuel system is a low pressure one up to the pump. This would allow air into the system while the car is resting and naturally presents as cold-start difficulties.

The way to find this is to pop the bonnet and pump the primer. It should only take 4 to 5 squeezes to go firm - but don't stop there. Keep going for another 10-15 squeezes and you should see diesel coming out of the leak.

If it is leaking, it may take more than 4-5 squeezes to get it firm too, so if you're on your 6th or 7th squeeze and it's still soft then you may have found the culprit. And I don't think I could use that phrasing anywhere else either!

Has only caused issues twice since last post, so seems to have settled down from what was a daily issue since replacing the scv.

Once primer bulb pumped up and over pressurized, cannot see any leaks, but can hear what sounds like an air/liquid leak up near the fuel filter/primer bulb. One hose clamp does the old slippy-slip when trying to nip it up that little bit extra, and a few others did nip up a little more than I was comfortable with, so we'll see how that goes.