Longer cranking times

[veebs]

Hi all,

I've noticed the old girl (3.0L 2010 D4) is taking a bit longer to kick over when starting in the morning, or when it's sat for a few hours or more without having been driven. No codes are coming up, though thinking now I could check the 'pending' codes section.

Anyway, one observation is that if I set the ignition to 'On' first, wait a few seconds, then push the brake and start the engine it generally fires much faster - just as it used to do all the time.

I'm wondering, if this might be a symptom of a weak fuel lift pump (ie, the pump in the tank). Due to an electrical gremlin the car was run dry a while back, and so this may be a result of that?

I changed the fuel filter which made no difference, and I think I've bled the diesel line in the engine (press the schrader valve with the fuel pump running) - not that it needed it.

Any other thoughts of things to check before I start pulling the fuel tank out?

[DiscoJeffster]

It won’t be the lift pump because the HPFP doesn’t really even need it to run.

Things that will affect crank times are
The ambient temperature - sub zero will mean the glow plugs are used
Crank signal - suspect or failing signal means it has to turn more to get a clean signal
Fuel pressure - injectors won’t fire until the HPFP provides the needed pressure.
Battery - not enough juice to fire up the ECUs

When my crank sensor started to fail it would crank longer randomly and sometimes not start. Eventually it wouldn’t start and then failed while driving.

You want to start logging with IID at various things, or just wait until it gets worse so it’s easier to troubleshoot.

[Graeme]

Displaying rpm while cranking, watching for rpm staying at or dropping to zero, is the dead simple way to rule-in or out the crank sensor and much better than waiting for it to fail totally.

[BradC]

The ambient temperature - sub zero will mean the glow plugs are used


Glow plugs are used pretty much any start unless it's a hot re-start even if the lamp on the dash doesn't illuminate.

Edit :
"When the ignition is switched on to position II, the glow plug warning lamp illuminates and the instrument cluster
displays 'PREHEATING' in the message center. The glow-lamp is activated separately from the glow-plugs, so is
not illuminated during or after start. The plugs can still be ON when the lamp is off in these two phases.

In the event of glow plug failure, the engine may be difficult to start and excessive smoke emissions may be
observed after starting."

[Ferret]

...Any other thoughts of things to check before I start pulling the fuel tank out?

Check the condition of the megafuse located off the positive pole of your battery.

I have recently had staring problems. The megafuse was intact but the fuse terminals had become badly burnt and pitted over the years causing resistance. Changing the fuse solved the problem.

189444

[DiscoJeffster]

Glow plugs are used pretty much any start unless it's a hot re-start even if the lamp on the dash doesn't illuminate.

I definitely notice a delay when it’s sub zero or near to when the glow plug light comes on and the start is delayed by a half a second or so, which led me to point that out when discussing starting delay - but I take your point [emoji1360]

[veebs]

Thanks all

It's done it in 35 degrees and above (I'm in Perth), so hopefully the sub zero effect can be ruled out...?

I'll definitely start logging with the IID and see if that yields some results. I'll also check the mega fuse - can't hurt

The glow plugs makes a bit of sense, if these are used irrespective of ambient temps.

The part that throws me is why it would behave normally simply by turning the ignition on for a few moments before starting. Maybe the glow plugs need a few extra seconds to warm up?

Really hope it isn't the crank sensor - I watched the Germans change theirs out (after some impressive oscilloscope work) and it looks like a royal PITA.

Which leaves the battery, and insufficient volts to fire everything up. Man, if that turns out to be the issue I'll feel like a right boob for asking - Disco 3/4 Maintenance 101!. I'll sit it on a charger overnight and see what happens first thing in the morning.

Thanks for the ideas!

[LuckyLes]

Battery would be my starting point. I'm on my third battery in mine and each time your symptoms are the same as I experienced.
Cheers. LuckyLes

[nut1304]

I am now facing the exact same problem as you. It is quite weird that turning the ignition on for a few moments before starting help. Would you mind sharing how you solve this problem please?

[RANDLOVER]

Also could be a Diesel leak or loose fitting letting air into the fuel system. I wonder if there's a one way valve in the fuel line that stops it draining back to the tank or if it relies on the natural vacuum of a closed system?

[veebs]

Haven't really solved it sadly, but the press - pause - foot on brake - press to start process is now all but second nature.

[BradC]

Have you actually tested the glow plugs to make sure they're all working?

The D3 has an old fashioned key and no automation so I turn the key and always wait for the glowplug light to go out before proceeding to start. I had a brainfart the other morning and just got in and cranked away. It cranked for probably double the normal time before it wheezed into life. So the plugs absolutely play a part in a cold start.

[nut1304]

Haven't really solved it sadly, but the press - pause - foot on brake - press to start process is now all but second nature.
Thank you. That also my starting process by now. If I know how to fix it, I will share in this post.

[Tombie]

Mines not liking the stone cold, its 100% glow plugs being end of life.

On those cold starts im just button on, let it glow once, then foot on, let it glow and go.

I'll do the glow plugs when i do the oil cooler

[RANDLOVER]

I think you can measure the resistance of the glow plugs to see if they are okay.

[BradC]

I think you can measure the resistance of the glow plugs to see if they are okay.

Unless it's an open circuit failure, without a milliohm meter you'd struggle and even then it means you need to remove the harness to check. Easiest way is a cheap DC clamp multi-meter. Check points 11->14 here : DISCO3.CO.UK - View topic - Robbie's Guide To Glow Plug Diagnostics (https://www.disco3.co.uk/forum/topic130145.html)

[veebs]

tested the plugs on the weekend, using the clamp meter - maxing out about 38A on both sides, and some 12.7A or so when testing a single cable.

Not definitive they are running at full spec of course, but it isn't the obvious issue I though it might be.

May instead need to look at the fuel system. Maybe a clogged or clogging filter or something.

[BradC]

Do you have a pressure gauge to test the LPFP?

[veebs]

I don't, however always entertain the idea of expanding my toolbox.

Is that a Schrader valve unit connected to the valve under the engine cover?

[BradC]

It is. I have one if you want to borrow it.

[veebs]

It is. I have one if you want to borrow it.

That would be awesome - though I'd need to know what pressure it SHOULD be at before i can do much with it :)

[BradC]

That would be awesome - though I'd need to know what pressure it SHOULD be at before i can do much with it :)

Start here : DISCO3.CO.UK - View topic - Robbie's Guide To The Low Pressure Fuel System (https://www.disco3.co.uk/forum/robbies-guide-low-pressure-fuel-system-130062.html)

Basically any significant positive pressure is good. The HPFP has a vane feed pump that could suck a golf ball through a straw, but having a positive pressure at its input stops it cavitating and bad stuff happening.

PM Sent also.

[RANDLOVER]

I tested the glow plugs, and they are not working except for 1, which seems to draw 0.6 Amps. I'm getting my mechanic to change them next month during the service. I hope he doesn't have trouble as they seem to have the strength of a biro according to Robbie's write up mentioned earlier.

[DiscoJeffster]

I tested the glow plugs, and they are not working except for 1, which seems to draw 0.6 Amps. I'm getting my mechanic to change them next month during the service. I hope he doesn't have trouble as they seem to have the strength of a biro according to Robbie's write up mentioned earlier.

Friends of yours they are not. Good luck

[shaf254]

Hello gentlemen.
Also facing the same issue. Tried to change the starter, the low fuel pressure pump, switching up nozzles as well.Is there any progress to troubleshoot this?

[DiscoJeffster]

Hello gentlemen.
Also facing the same issue. Tried to change the starter, the low fuel pressure pump, switching up nozzles as well.Is there any progress to troubleshoot this?

Have you got a scan tool so you can scope the rpm signal? Check it's getting a stable rpm value at startup. If not, it could be the crank angle sensor. I had to replace mine.

[shaf254]

Thanks for the response.
I do have a gap tool that can read values. What should I look out for? Is this on the first crank? Also are you referring to the crank shaft position sensor part number LR009793? Is it just replacing with no need to program it? Did this resolve your issue?