Thread: Weird Electrical problem with fuel filter sensor

Originally Posted by Noisy

Really? Different cars must do different things, i had a car once and the immobiliser would let it crank but cut all fuel and spark so it would never run.

As we speak here about the D2 Td5 that's it:

Originally Posted by Discovery Td5 - Body control unit - DESCRIPTION AND OPERATION 86-3-19

Immobilisation

For immobilisation, the BCU disables the starter motor relay.
.....
If the BCU is disconnected, the engine starter motor will remain isolated by the starter motor relay and the ECM will
remain immobilised. ....

Ok so this problem happened again, just got home from a 150km+ trip drove in the driveway parked on the front lawn and turn it off (after a bit of a cool down) then the kids tell me the window were stilll down so key in to wind up and notice the m and s flashing so i tried to start and no go, just turned over no start. Unplugged the fuel water sensor and back to normal started right up, turn it off plugged it back in and fired right up again. Went inside and grabbed the nanocom and had zero faults. So is it just an electrical problem or something more sinister? Would a faulty fuel pump log and error to the nanocom? Car runs fine other then a bit slow on hills but no problems otherwise

Edit rechecked with nanocom and in the auto part "code p1843 can timeout monitoring" came up quick search says its to do with inertia switch and when activated the fuel pump is cut off. Which is what the car is doing turning the fuel pump off but how/why does it work by just unplugging the water in fuel sensor

Your water sensor is just coincidence.

Originally Posted by strangy

Your water sensor is just coincidence.

A coincidence every time? That is what i find funny that every time it does it all i do is unplug it and it fixes whatever gremlin is there, i am really thinking about just leaving it unplugged though it is there for a reason. A bit more searching around the fault seems to be caused by oil in the harness which i do have and i let it drain a few months ago while i had the battery out and got a little bit out, nothing out of the ecu though.

*Unplug the fuel filter water sensor, fold it back up above the chassis and zip tie it, then forget about it.
*The sensor is fragile, unreliable, expensive and prone to damage from debris.
*A TD5 Defender has no water sensor.
*Change fuel filter out on a regular basis such as every 10,000kms when doing service.

Originally Posted by Noisy

.....Which is what the car is doing turning the fuel pump off but how/why does it work by just unplugging the water in fuel sensor

It might be another thing made on purpose by LR to protect the engine from water but not mentioned in documents or the sensor has some internal short cos it's is on the same circuit with the fuel pump on the relay's output and it completes internaly an earth path to bring up the warning lamp then there can be a big voltage drop on that circuit not enough to blow the fuse but enough to disturb the pump's rpm stopping it to deliver proper pressure.

warter sensor.jpg

Originally Posted by INSTRUMETS -DESCRIPTION AND OPERATION 88-29

........
The water sensor provides the earth path to illuminate the warning lamp. The voltage on the earth path from the sensor to the instrument pack is as follows:
< 1.8 volts = warning lamp on.
> 7.7 volts = warning lamp off.

Originally Posted by Noisy

Maybe that is option here then just delete the whole sensor and put a bolt in. I like the idea of the sensor though as it should tell you of crap in the fuel and warn you before any damage.

If it's been a couple of years since the fuel filter was changed, just replace it! They come with a drain tap on the bottom. Every time you do a service, or grease the uni joints, drain off an egg-cup full of fuel. Easy to spot if there is any water in it. Do it more often if you are fuelling up from jerry cans, or from low volume service stations.

My td5 Defender has one on it

Originally Posted by DazzaTD5

*Unplug the fuel filter water sensor, fold it back up above the chassis and zip tie it, then forget about it.
*The sensor is fragile, unreliable, expensive and prone to damage from debris.
*A TD5 Defender has no water sensor.
*Change fuel filter out on a regular basis such as every 10,000kms when doing service.