Defender TD5 (2001 - 15p) Wont Start

[Mark Monkey]

Hi

 

Landy was starting fine but had trouble starting it when warm. Read it could be a fault crank sensor, so set about changing it. Now it wont start - replaced with old one, and still wont start. Inspected wiring and it looks ok - and both sensors measuring 1.2ohm so believed to be ok.

 

I'm running out of ideas to test - so I've formulated this 'battle plan' for the weekend. Have I missed anything?

 

Approach

1.       Ensure that your battery is in good condition and fully charged at around 12.3-12.6 volts. If it drops below 10.5v when starting, it will not start. The battery should show 14v when the engine is running.

 

2.       If it’s a TD5 with an immobiliser, try resetting it, which involves a sequence on the key fob on unlocking and locking.

 

3.       Check the Inertia Switch has fired – centre of the firewall in the engine bay, it pops up if fired, just push it down. Its there to cut off fuel in the event of an accident.

 

4.       Check there isn’t oil in your ECU (under the driver’s seat, red cable – disconnect battery beforehand). If there is oil, clean it using contact cleaner and reconnect. To prevent it, this is typically a failure on the injector harness (See Replacing Injector Harness on TD5) where oil seeps through the connector and down the wire, which with movement, makes its way into the ECU plug. I’ve seen some raise the ECU into a vertical position to prevent this as well as help with water ingress, if you go mad when off-roading).  NOTE: Oil can eventually make its way into your ECU and break it.

 

5.       If could be a fuel issue,

a.       Turn the ignition to II position, fully depress the throttle 5 times, the engine management light with flash, then wait until the engine management light stops flashing and crank it

b.       with multimeter set on mV measure across fuse F10(30A) in situ while the pump(or engine) is running, according to the attached chart by mutiplication if the HP is working you should get around 23.mV reading(or more) which means around 13A current draw , if it's only around 10mV(= 5A draw) the HP is dead but the pump is still running on LP

 

6.       The Crank Sensor (a Variable Reluctance Sensor (VRS)) can stop a TD5 from starting, it should register around 300 rpm when cranking otherwise the ECU wont engage the fuel pump – the starter motor could also be at fault. If you’ve a Nanocom, using the ‘Inputs Fuelling’ setting, you can get an engine rpm reading when cranking/towing. If you’ve a Nanocom, and you see no RPM when either cranking, it could be the sensor, circuit issue or the bad starter motor interference. Try bump-starting it/towing it, if it starts, it’s the crank sensor sensor – if it doesn’t start, then it’s the starter motor.

 

If you’ve a Nanocom, and you see no RPM when either cranking it from standstill – or pushing/towing, then, the reasons could be one of the following.

a.       The Crank Sensor is faulty. You can test it by measuring the Ohm between the connectors directly on the sensor, and it should read around 1.2 Ohm.

 

b.       The wiring to the sensor could be faulty. The Crank Sensors location is such that it is prone to oil and heat, and this can cause the wire to become brittle – and its not in the easiest place to repair – if you have to, Its recommend fitting a new connected, by either splicing it to the old one OR fitting a new connected direct to the ECU. To test, Insert a probe into cavities 13 and 36 on the back of the red plug to the ECU and measure the resistance. If it doesn't measure 1.2 ohm, then its wiring.

 

c.       The Starter-Motor could be interfering with the Crank Sensor (they are close, and worn bushes creates interference). You sometimes see a ‘noisy crank signal’ on the Nanocom if this is the case, but not all the time.

 

7.       If the Crank Sensor is working and the Starter motor is working but it still won’t start, it could be a Fuel Issue, either the non-return valve on fuel distribution head). Switch the pump into purge mode, this will cycle the fuel pump. You can now check you a have a charge on the Relay to the fuel pump (R103) which should be energised with Pin 30, 87 and 86 going live, and you can also check this on the fuel pump itself – or listen for the fuel pump priming sound.

 

8.       If its not the crank sensor, the starter motor, or the fuel-pump, it could be the seals on the injectors. Over time these wear thin/corrode and lets diesel through into the compression chamber, making it hard to start – if this happens, you often see diesel in the oil and the oil level rise. If this is the case, change the copper washers on injectors (See Changing Injector Copper Washers) and clean your oil – you’ll need injector pullers, or a small allen key fashioned into a level, to live the injector free.

 

*** now I've run out of ideas

 

TIA,

Mark

[simonr]

That's a pretty comprehensive list!

Check the easy / obvious things first.  Low battery is the most common.  Check the battery earths while you are at it.  Personally, I run a heavy (35 sqmm) cable straight from the battery -ve to one of the starter motor mounting bolts.  The earth via the chassis is a terrible idea - they always corrode badly.

No fuel is the next most common -and you've covered most bases other than air in the fuel.  This can be hard to spot / diagnose.  I eventually diagnosed mine using a length of clear hose so I could see the bubbles.  I replaced all the fuel lines back to the tank - figuring that if one was drawing in air, others will soon, so replace all.  I didn't expect air to be drawn in through the pipe fittings as they are under pressure.  I can only figure a tiny hole acting like a venturi & sucking in air as the fuel flows past.

Point 4.  After you've cleaned the plug & socket (remembering to remove the plastic terminal cover inside the plug, fill the interior with as much petrolium jelly as will fit.  When you plug the two halves together, it should extrude out of every hole under pressure.  This largely stops the oil from getting back in to the connector or ECU.  Did mine 15 years ago and never had a problem since.

Crank position sensors, particularly cheap patterned ones are affected by heat - so not starting when hot is often a sign of the sensor.  That could be part of your original problem.  I would fit the old one and swap it out if it won't start when hot.

[Anderzander]

Another one is the Earth for the ECU under the seat - easy to check and easily missed.

[Mark Monkey]

So – it’s been a ‘fun’ afternoon of diagnostics (at least it was sunny)

 

1^st – Battery was charged, showing ~13v when disconnected, and when cranking still shows ~11v, so its getting enough power (it’s a BIG 110ah battery 😊)

 

ECU plug was clean, but I removed the plug, cleaned it again with IPA, and added petroleum jelly and refitted.

I replaced the crank sensor with my replacement, and a spacer), checking the resistance before fitted (1.26ohm) and when fitted and connected via pin 13/36 on ecu (1.27ohm), so I believe the wiring is ok (it looked ok).

It’s cranking, showed around ~290 on crank sensor (friend observed it) from the Nanocom, but wouldn’t fire.

 

Its had a new fuel header inc. connectors and valve – and a new fuel filter a few weeks ago, and was starting fine after it, so I didn’t look there.

Purged the pump – I can hear the pump humming but no gurgling sounds or anything. Pump is receiving 12v on its live post relay.

So checked for pressure. Disconnected the HP feed which goes from the pump (to the HP input of the fuel regulator (green collar) and there is no pressure, barely a dribble when cranking.

 

I don’t have a multi-meter that will go above 10amp, so can’t test it inline using the 20a fuse (found here)

 

I’m not sure how the fuel pump/filter work. It seems to go via the filter via a LP pipe to filter the fuel, and then goes to the fuel pressure regulator (Pipe 8 on diagram). Its here I’m seeing no pressure.

 

a.       Fuel Pump? Do I need to buy a new multi-meter, or is there another way of testing whether the pump itself is working?

b.       Could the valve from the fuel pump to the fuel filter via the distribution head be faulty, or blocked – should I crack it and see if fuel is coming out? (Pipe 7 on diagram)

c.       Anything else??

 

TIA.

[simonr]

>b.       Could the valve from the fuel pump to the fuel filter via the distribution head be faulty, or blocked – should I crack it and see if fuel is coming out? (Pipe 7 on diagram)

Yes!  That's where I'd start.  If the pump is wirring, but there's nothing at this point, it could be the gause filters on the pump being clogged.  You have to remove the pump to find out - and if it's not the filters, it must be the pump!

While the pump may have a 20A fuse, it's unlikely to draw more than a few amps.  I'd try it with your 10A meter which will likely have a 10A slow-blow fuse inside.  If it reads over 10A, so long as you disconnect quickly, it won't blow the fuse.

If there is pressure at Pipe 7, change the filter.  It's possible it's no good (particularly if a patterned part)

[Mark Monkey]

Awesome, thanks Simonr, I'll give that a go first.

[Troll Hunter]

Mark Monkey posted;

Purged the pump – I can hear the pump humming but no gurgling sounds or anything. Pump is receiving 12v on its live post relay.

Surely this indicates that the supply line is not purged of air.  I have had a similar situation on a non-LR motor. Having run out of diesel fuel, I added about 10 litres of diesel to the tank and bled the system at all possible points. This didn't solve the problem.   The problem was that the inlet to the FIP was fractionally above the fuel level in the tank.  Addition of a few more litres of fuel resolved the problem, and my machine started just fine.  So, really check your fuel levels, to the millimeter.  Gravity rules.

Mike

[Rick Upart]

On 4/26/2021 at 3:50 AM, Mark Monkey said:

So – it’s been a ‘fun’ afternoon of diagnostics (at least it was sunny)

 

1^st – Battery was charged, showing ~13v when disconnected, and when cranking still shows ~11v, so its getting enough power (it’s a BIG 110ah battery 😊)

 

ECU plug was clean, but I removed the plug, cleaned it again with IPA, and added petroleum jelly and refitted.

I replaced the crank sensor with my replacement, and a spacer), checking the resistance before fitted (1.26ohm) and when fitted and connected via pin 13/36 on ecu (1.27ohm), so I believe the wiring is ok (it looked ok).

It’s cranking, showed around ~290 on crank sensor (friend observed it) from the Nanocom, but wouldn’t fire.

 

Its had a new fuel header inc. connectors and valve – and a new fuel filter a few weeks ago, and was starting fine after it, so I didn’t look there.

Purged the pump – I can hear the pump humming but no gurgling sounds or anything. Pump is receiving 12v on its live post relay.

So checked for pressure. Disconnected the HP feed which goes from the pump (to the HP input of the fuel regulator (green collar) and there is no pressure, barely a dribble when cranking.

 

I don’t have a multi-meter that will go above 10amp, so can’t test it inline using the 20a fuse (found here)

 

I’m not sure how the fuel pump/filter work. It seems to go via the filter via a LP pipe to filter the fuel, and then goes to the fuel pressure regulator (Pipe 8 on diagram). Its here I’m seeing no pressure.

 

a.       Fuel Pump? Do I need to buy a new multi-meter, or is there another way of testing whether the pump itself is working?

b.       Could the valve from the fuel pump to the fuel filter via the distribution head be faulty, or blocked – should I crack it and see if fuel is coming out? (Pipe 7 on diagram)

c.       Anything else??

 

TIA.

Do you found a solution? I have to found why my defender td5 crank but not start…that’s why i was following your tread.

[Mark Monkey]

So my solution to the above was a new fuel pump. Fitted, as you can see in July 2021.

Here we are in October 2022, and after a short journey my Defender broke down on the M4. Six hours later I was eventually recovered (M4 closed, slow traffic), and the waiting AA man said failed fuel pump ( voltage at the fuel pump connection but no noise).

I thought it strange given its not very old and done hardly any miles but it was an BEARMACH one, not OEM or Genuine, so I ordered a new VDO one (£284!)

Fitted and the Defender still wont start - cranks but not firing. The Pump on purging is silent. Its getting 12v to the connection when cycling. Before I start cracking the pump line and check its actually not pumping, any other ideas.

This is really starting to irritate me.

[steve200TDi]

I guess you've done the purging cycle, ignition on and 6 accelerator presses does it. I know mine took loads of cranking to get all the air out and it eventually started.

Steve

[Anderzander]

⬆️ Turn the ignition on and pump accelerator 5 or 6 times. The engine light should flash and you should hear the fuel pump making noises.

If the engine light doesnt flash then I think it’s an ecu issue (see my previous comment about the ECU earth), if it flashes but there is no noises in tank - then it points to your pump problem.

[Maverik]

On 10/9/2022 at 5:45 PM, Mark Monkey said:

So my solution to the above was a new fuel pump. Fitted, as you can see in July 2021.

Here we are in October 2022, and after a short journey my Defender broke down on the M4. Six hours later I was eventually recovered (M4 closed, slow traffic), and the waiting AA man said failed fuel pump ( voltage at the fuel pump connection but no noise).

I thought it strange given its not very old and done hardly any miles but it was an BEARMACH one, not OEM or Genuine, so I ordered a new VDO one (£284!)

Fitted and the Defender still wont start - cranks but not firing. The Pump on purging is silent. Its getting 12v to the connection when cycling. Before I start cracking the pump line and check its actually not pumping, any other ideas.

This is really starting to irritate me.

On opening up the fuel system, I remember it taking about 5 sets of purges to get the pump primed - but you do here a gentle humm until it picks the fuel then is sucks and gurgles a bit.

Now you say you're getting 12v at the connection, but are you getting voltage breakdown on load - common for s poor contact somewhere? when I was diagnosing electrical issues on my van I got a set of "Automotive Break out leads" they allow you to measure the voltage by jumping the connection so you can monitor the voltage - you can actually make some leads up fairly easily. - have you checked the condition of the contacts in the mutliplugs from the bulkhead loom to the chassis loom?

 

Did you also follow up on the earth issue - I remember my father in laws 90 kept stopping a bit like you, and it was an ECU earth under the drivers seat.

[Filbee]

I'm sure you've already checked, but is your fuel pump relay in good shape? I had intermittent starting issues with my TD5 when I first got her. More by luck than judgement I found that my fuel pump relay had been overheating at some point and was getting a bit melted. I swapped it for a new one and it's been fine since (touch wood 🤞).