Cold Start, dies when idling

An issue that's developed over the last few days - starting from cold, after the glow plug light has gone out, my 90 will start without issue, run for 20 secs or so and then rather abruptly die, repeating yields the same results. If I keep the revs above 1k then no issue, it's only when it drops to idle revs, it dies.

Give it 5-10 minutes of driving, once everything has warmed up then it will sit at idle fine

We've had a cold spell here the last few days and I'm usually starting the 90 early morning / late evening, maybe -5c temps, unsure whether this is playing a part or just coincidence?

I've checked the MAP and MAF sensors and gave them a clean, this has sorted ropey idle issues for me in the past but no change here.

Any advice on next port of call? I thought this may be a glow plug issue, but given that it will start and run for a short while (by which point I had thought they would have turned off), i'm not so sure?

Have you changed your fuel filter lately, could be partially blocked.

Diesel starts to wax at 0C. Are you running winter diesel or the normal stuff. If the temps rise and you don’t have the same prob, it strongly suggests the diesel issue but check all the normal fuel related items to be sure.

We run diesel rated for -30C but we get temps down to -20C

M

marjon said:

Diesel starts to wax at 0C. Are you running winter diesel or the normal stuff. If the temps rise and you don’t have the same prob, it strongly suggests the diesel issue but check all the normal fuel related items to be sure.

We run diesel rated for -30C but we get temps down to -20C

M

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UK diesel is good to approx minus 20

johnlad said:

UK diesel is good to approx minus 20

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Not all fuel stations sell winter diesel.

M

Getting warmer over the next couple of days up here, see if it still does it.

It sound as if your fuel is being airiated is your fpr leaking?

If it keeps doing it in warmer conditions suspect a small air leak. [ a bit of air gets in when standing ]

Hi all, thanks for the responses.

The last few days have been much warmer but no improvement with the stalling when cold, so can rule out the temperature I think. Air in the fuel seems much more plausible.

I had a quick look at the fpr last night and couldn't see anything obvious externally - but not really sure what I'm looking for there! I'm assuming I'm going to have diesel leaking out to be allowing air in?

Does the puma have a non-return valve on the fuel filter assembly like a TD5?

Is it worth picking up a diagnostic scanner? I'm assuming I'll get some sort of error code on the fuel pressure... but doubt it well help me identify where the root cause is?

Cheers

LiamMBW said:

Hi all, thanks for the responses.

The last few days have been much warmer but no improvement with the stalling when cold, so can rule out the temperature I think. Air in the fuel seems much more plausible.

I had a quick look at the fpr last night and couldn't see anything obvious externally - but not really sure what I'm looking for there! I'm assuming I'm going to have diesel leaking out to be allowing air in?

Does the puma have a non-return valve on the fuel filter assembly like a TD5?

Is it worth picking up a diagnostic scanner? I'm assuming I'll get some sort of error code on the fuel pressure... but doubt it well help me identify where the root cause is?

Cheers

Click to expand...

Don’t assume you will have diesel leaking out, because air is getting in. I know mine is a TDI, and yours isn’t, but on mine I had at least one, but more likely more, air leaks and no diesel leaked at all.

I found mine by installing a piece of clear tube on the fuel feed line, but I don’t know if I would trust that on a TD5 as it’s presurised from the intank pump, not sure about a Puma though?

To come back to this a month or two later, whilst the problem sorted itself out, I never managed to nail down exactly the problem!

A couple of further cleans of the MAP and MAF, plus the addition of Millers treatment each time I fill up are all I've changed - perhaps I'll put it down to a dodgy batch of fuel!

You never know, I once filled at station some way from home and half a mile down the road there was a noticable drop in power. When down to half I filled it right up and only a few hundred yards down the road there was a jump up in power.
Heard later that the first station had been thinning the derv with something iffy.

The puma fuel system will tolerate small amounts of air getting in. The fuel pump is self bleeding. Unless there is a major leak and large amounts of air is getting in, this is unlikely to be the problem. Have a look at the filter, there is a water drain off tap at the base of the filter - give it a drain and look at what comes out. Also check around the filter for corrosion, when I changed mine it was nearly rotted out . Your idea of getting a diagnostic is a good one, definitely worth doing as it should show up stored issues.