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othorton

TD5 Cut-Out

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Hello - New Member Alert!

Defender TD5, 2005, 105k Miles

Possibly chipped, EGR Removed. For the record I am a complete mechanical novice - but I am keen to learn and this is why I bought it. 

Background: I'm having issues with my (new to me) Defender 90. I've had it since Aug Last year, done approx 3k miles in it since then and it's largely been a dream to drive and own. However, about a couple of thousand miles into ownership I had an issue with the defender where it would seemingly cut out at random. It went back to the dealer I bought it from and there was warranty work carried out. They replaced the injector harness and apparently found some fuel pump wiring issues. After sorting this issue, I had the defender back and it gave me another thousand or so miles of driving. The defender was serviced just before I bought it and will be due one next month. 

The issue: Defender drives fine when accelerating through the gears, idles fine and starts fine. The fuel pump is noisy but has been since I bought the defender and hasn't been a cause for concern. When moving, at any speed and in gear, once I lift off the accelerator and the car begins to decelerate it cuts out. By 'cuts out' I mean, the orange engine warning light comes on, the engine stops running and the fuel pump is silent. If you try to start it straight after this happens the engine will turn over but not catch. Taking the keys out the ignition and waiting a couple of minutes, she fires up as if nothing happened. This is seemingly random - it doesn't do it every time you coast, but I was able to quite reliably cause it to occur twice yesterday. Quick note - there is no hesitancy in the high revs. It pulls powerfully through all gears. When travelling and you depress the clutch the engine goes back to idle and doesn't cut out. It's only when decelerating with the engine in gear.

What I've checked so far: All the relays under the driver's seat/the battery connection/oil in the ECU (there is none). The injector harness was replaced recently. The fuel pump works.

As a preventative measure I'll be replacing the fuel filter as it doesn't look to be very new. 

I'd really appreciate any advice from the Forum - I've been active on Def2 but have been told to cast my net to you guys whose advice is usually invaluable. Has anybody had the same problem? As a related question - are there any London based forum members who have a Nanocom I could borrow to check any fault codes please.

Many thanks in advance,

Othorton

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When you try to restart can you hear the pump running with just the ignition on?

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Hi BigJ. At any time when I put the key in the ignition and turn to position 2 I can hear the pump. This is both when first starting the car and after it cuts out.

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Hi and welcome.

As you've already alluded to, you really need to see what fault codes are present, anything else is purely guesswork and can end up quite expensive, if it's bringing the MIL on during the fault condition this will be logged and remain in memory even after it's self cleared.

Even if the in-tank fuel pump isn't running, the engine will still start and run, albeit with reduced power, there is sufficient "lift" from the injectors to allow this.

If the main relay under the seatbox or the crash sensor on the bulkhead drops out,  the engine will stop but won't put the MIL on, it's the same as switching the ignition off and not seen as an error.

If the crank sensor failed, that would cause the engine to stop but it's very unlikely to be "self-healing" by cycling the ignition.

It's always worth checking for any add-on aftermarket alarm wiring or mystery boxes of any kind, these can often make fault finding notoriously difficult.

as I said before, getting a code reader on there must be the first priority.

 

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Welcome Othorton 👍

Mo

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Where are you based? London is a big place!

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I would put money on the loom being chaffed where it crosses over the top of the transfer box, particularly if it does it when you lift off and the transfer box shifts on its mounts...

Remove cubby box and access panel beneath and check the loom thoroughly.

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Thanks for the advice chaps. I'm based in the Waterloo area. I'm taking it up to Mo Saturday next where I can give the nanocom a look and to check a few things with their expertise. Dave - just a thought - the engine doesn't cut out when I de-clutch when on the move: would the transfer box not also move when the defender goes from drive to neutral?

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On 1/13/2020 at 7:51 PM, dave88sw said:

I would put money on the loom being chaffed where it crosses over the top of the transfer box, particularly if it does it when you lift off and the transfer box shifts on its mounts...

Remove cubby box and access panel beneath and check the loom thoroughly.

I had a very similar problem with my Softdash RRC some years ago and it turned out to be the loom had been touching the exhaust at some point before I owned it and had burnt through the insulation. The loom had been tucked back up but the damage had not been repaired. Every now and then when going over a bump or cornering the bare fuel pump feed earthed out on the chassis and blew the supply fuse. When I tested the loom it seemed okay as the wire was no longer earthed and the supply voltage to the pump was fine, until the next time it touched and so on.

Took ages to trace it as it was quite high up in the chassis but although this fault sounds similar, it’s strange that the pump always runs immediately after it cuts out which is why I asked my original question. Ordinarily, you would expect a fuse to blow if there was even a temporary short to earth but maybe this is just an odd case 🤷‍♂️

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17 hours ago, Bigj66 said:

 

... Ordinarily, you would expect a fuse to blow if there was even a temporary short to earth but maybe this is just an odd case 🤷‍♂️

Not necessarily, modern(ish) automotive fuses seem to have a huge overload tolerance, such that rubbing an exposed wire against a dirty or corroded metal surface can cause sufficient electrical disturbance to cause errors in the system but not pass enough current to blow a fuse, depending on what circuit it's connected to of course.

Similarly, a lot of the sensor inputs into most ECU's operate at a very low power such that a minor leak to earth or to another conductor can cause some unpredictable faults, for example the intermittently self-opening tailgate on my Freelander 2 which turned out to be due to moisture inside the switch in the tailgate handle.

Or, on one of my previous Td5 90's which would intermittently fail to start with one of the relays making a squealing noise, this turned out to be water ingress (again) into one of the multi-way "headers" under the driver seat box causing electrical leakage between 5V, 12V and ground.

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