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TD4 Starting problem


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#1 RJF

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Posted 20 August 2011 - 03:41 PM

Hi,

Over the last few days my TD4 has been getting harder and harder to start. It used to be two engine turns and it started, now it's more like 5 seconds or more cranking. I initially thought glowplugs. The warning light on the dash does not illuminate.

I have checked the glowplugs (ok), wiring to plugs(ok), glowplug relay in e-box(ok), fusible link (ok), relay coil power (ok), ECM to relay coil link (ok).

I get no demand from the ECM (the voltage on the ECM output at the relay coil is constantly at battery volts whereas it should drop to 0V to energise the relay. The relay itself works ok and can be energised with a jumper link and the plugs heat.

I am getting to the conclusion that the ECM is not asking for glowplug power, so my question is.... What makes the ECM decide to fire up the plugs?

I've read various sensors on a code reader and the all present plausible values.

I'm confused

Rob.

#2 RJF

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Posted 20 August 2011 - 03:42 PM

Sorry, forgot to add...

08/2001 TD4 5dr Auto
VIN 1A337xxx

Rob

#3 Ally V8

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Posted 22 August 2011 - 12:07 PM

Sounds like low fuel pressure on the low side of the system,which can be down to several things.Common causes are failing low pressure electric pumps,blocked filters,failing pressure regulator on the high pressure pump or excessive leakback through one of the injectors.On live data the fuel pressure should be above about 280-300pa and not drop off too much when revved.
In a UK summer the glows are not needed for starting,but the ecu may chose to use them to lower emissions after starting.(Without putting the lamp on.

#4 RJF

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Posted 23 August 2011 - 02:09 PM

Thanks.

Once it finally starts it is absolutely fine.

I've had a listen to both LP pumps. The one in the tank makes quiet pump type noises and the one by the filter in the engine bay seems to gurgle quite a bit (more than I remember).

I have a spare fuel filter in the garage, so I'll swap that out.

Thanks,

Rob

#5 MrKev

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Posted 23 August 2011 - 02:15 PM

You've probably got too much Wales stuck in there somewhere :P
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#6 perv

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Posted 24 August 2011 - 11:45 AM

When it starts you said it runs fine so I would'nt suspect the pumps.

Maybe worth getting the Injector leakback ckecked.

Regards Ash

#7 RJF

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Posted 11 September 2011 - 03:43 PM

Just to follow up on this...

Turns out it was the in-tank pump that had failed. It wasn't too hard to change, but what horrified me was the big black flakes of gunge in the bottom of the tank!




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