Thread: Longer cranking times

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.

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.

Originally Posted by DiscoJeffster

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."

Originally Posted by veebs

...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.

Megafuse.jpg

Originally Posted by BradC

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

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!

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

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?