lhandrover · Oct 11, 2013

I have a TD5 DISCO 1999 - Today it was running perfectly, my Wife took it in to Garage and fueled up - 30 sec after pulling out of garage is started running rough and got rougher until it conked out. I've checked the receipt and sniffed the tank - it hasn't got petrol in it. As she said it was low fuel light on when she took it in I searched on here for the priming sequence (and looked in handbook) and did the 6 times ignition on 30 secs etc - No good, however I could not hear any noise coming from the fuel tank/pump - Is that because it has already primed and will not pump any more? Fuse perhaps? Or coincidence the pump decided to pack up without any warning at all?

johnlad · Oct 11, 2013

pump shafted

lhandrover · Oct 11, 2013

johnlad said:
pump shafted

A bit more info - When I did the 6 times off and on ignition etc - I've read that the engine light should stay on, it doesnt - its on momentarily and then goes off with all the other lights (I think 3 reds were left on thats all, but the yellow engine goes off) - Correct?

sierrafery · Oct 11, 2013

if you want to be 100% certain make sure that the fuse and the relay are good, F10 and R1 in engine bay, swap it with R3/headlamp wash for test) then put ignition on and measure voltage at the pump's plug(back=earth, white/purple= feed)..if you have voltage there and the pump rests it's deffinately goosed...if no voltage i'll tell you more.

lhandrover · Oct 11, 2013

sierrafery said:
if you want to be 100% certain make sure that the fuse and the relay are good, F10 and R1 in engine bay, swap it with R3/headlamp wash for test) then put ignition on and measure voltage at the pump's plug(back=earth, white/purple= feed)..if you have voltage there and the pump rests it's deffinately goosed...if no voltage i'll tell you more.

Cheers - I'm on it - report back tomorrow

lhandrover · Oct 11, 2013

PS - Just found out why it failed as it did - Apparently the fuel pump pressurises the tank, and as long as you don't open the fuel cap or have some other kind of leak, even when the pump fails the car will run pretty much as normal - open the fuel cap (as my missus did to fuel up) and pressure lost, runs like a bag of spanners and conks. Now to see why it stopped, if it's a fuse then I'm buying an extra lottery ticket tomorrow. But I think we know where this is going, don't we...

sierrafery · Oct 11, 2013

lhandrover said:
PS - Just found out why it failed as it did - Apparently the fuel pump pressurises the tank, and as long as you don't open the fuel cap or have some other kind of leak, even when the pump fails the car will run pretty much as normal - open the fuel cap (as my missus did to fuel up) and pressure lost, runs like a bag of spanners and conks. Now to see why it stopped, if it's a fuse then I'm buying an extra lottery ticket tomorrow. But I think we know where this is going, don't we...

this theory is a bit wrong..., but the conclusion is the same

...as the pump must not pressurise the tank whatsoever, there is an air ventilation system to avoid that... which if fails there'll be more like vacuum than pressure

the engine while is running keeps the pressure in the system and "sucks" the fuel,(it's kinda like in Boyle's self flowing flask) untill the pressure will slowly fail under the needed limit, then it stops, and as the pump is gone it will not start again.

thebiglad · Oct 12, 2013

lhandrover said:
I have a TD5 DISCO 1999 - Today it was running perfectly, my Wife took it in to Garage and fueled up - 30 sec after pulling out of garage is started running rough and got rougher until it conked out. I've checked the receipt and sniffed the tank - it hasn't got petrol in it. As she said it was low fuel light on when she took it in I searched on here for the priming sequence (and looked in handbook) and did the 6 times ignition on 30 secs etc - No good, however I could not hear any noise coming from the fuel tank/pump - Is that because it has already primed and will not pump any more? Fuse perhaps? Or coincidence the pump decided to pack up without any warning at all?

Just for your general info, there are only two methods for priming the fuel system:

1. Turn on ignition to pos two and leave for approx three mins or until the pump stops pumping, whichever is the shorter;

2. Method 2 - turn the ignition to pos II; immediately press and release the throttle pedal 5 times and the engine warning light will come on - then then leave to allow the system to bleed.

When you fit a new pump (the likely scenario in my opinion) I would suggest that you use method one, for priming the fuel system.

lhandrover · Oct 12, 2013

Thanks everybody - it was the pump - all up and running again.
Just a note for anyone doing this, I only found this tip after a lot of searching while I was struggling - when reassembling make sure you place the seal in its groove on the tank before attempting to finally push home the pump and tighten the lock ring - its virtually impossible to get the ring started if you don't

jamesmartin · Oct 12, 2013

lhandrover said:
Thanks everybody - it was the pump - all up and running again.
Just a note for anyone doing this, I only found this tip after a lot of searching while I was struggling - when reassembling make sure you place the seal in its groove on the tank before attempting to finally push home the pump and tighten the lock ring - its virtually impossible to get the ring started if you don't

very true

myjosef14 · Mar 11, 2014

This is a fantastic thread which helped me out no end, my pump failed with the same symptoms after using the advice above ordered a new pump and the day it was delivered Disco was back on the road.
Once again Landy Zone has helped me out, thanks chaps, great resource.

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