td5 fuel pump died....fits new one..works then dies...

Hi guys.

My Td5 Defender exhibited the symptoms of a failing fuel pump during the week, really struggling to accelerate at points, flat spots etc. Got back the place we were staying (on holiday) and changed the fuel filter incase that was causing it. Made sure I filled filter up with diesel. I went to purge the system and the pump made no noise at all on starting this procedure. Tried several times and nowt. Started the engine ok and hoped it would kick in but once the fuel in engine ran out, that was it.
Got it replaced yesterday (Friday) and took it for a good 40 mile run last night, no issues. Went to leave holiday site this morning and the same thing happened. Engine conked out and new pump has gone silent/won't prime.
Now, theres little/no chance that this new pump is a dud, and it seems the old one might have not actually been broken, just something causing it not to work. What are we thinking, something tripping? Fuse? Electrical? Bad earth?
It's getting recovered in the next day or so and taken back to original garage that fitted pump, should their diagnostics machine be able to make anything of any fault codes?
Thanks

It's possible that you have listed the cause there lift the drivers seat and pull out the relays one by one clean the contact blades on the relays and in the relay sockets, if possible I spray mine with a squirter of wd40 and work them in and out a few times.
While you are under there pull the red plug off the ECU and check for oil, if it is oily the clean it out I have used brake cleaner spray.
Check the fuse and look at the contacts give them a clean like the relay contacts.
Hope you find it.

raywin said:

It's possible that you have listed the cause there lift the drivers seat and pull out the relays one by one clean the contact blades on the relays and in the relay sockets, if possible I spray mine with a squirter of wd40 and work them in and out a few times.
While you are under there pull the red plug off the ECU and check for oil, if it is oily the clean it out I have used brake cleaner spray.
Check the fuse and look at the contacts give them a clean like the relay contacts.
Hope you find it.

Click to expand...

thanks man.
When the pump stopped working the first time this week I took out the relays and gave them a good clean and swap over but made no difference. Got the new pump fitted and it all sprung back into life again. Now it looks like it wasn't the pump and the act of changing the pump has nudged something else to work again. Do you know what fuse under the drivers seat is for the fuel pump?
One more question, does the fuel pump itself have an internal fuse?
thanks

Any muck in the fuel causing it to stop and choke ?

Oh, just read the above post ...

I had a brand new oe one sound worse than the one it replaces Ed and then fail 6 weeks later.
I'm still waiting on my landrover refund 4 months later.

defendermikey said:

thanks man.
When the pump stopped working the first time this week I took out the relays and gave them a good clean and swap over but made no difference. Got the new pump fitted and it all sprung back into life again. Now it looks like it wasn't the pump and the act of changing the pump has nudged something else to work again. Do you know what fuse under the drivers seat is for the fuel pump?
One more question, does the fuel pump itself have an internal fuse?
thanks

Click to expand...

Sorry I'm not sure which fuse it is.

raywin said:

Sorry I'm not sure which fuse it is.

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no problems, but it should be one of the ones under the drivers seat, I'd imagine?

Start simple, check relay is putting out power not just voltage but actual power, then check again at the plug on the pump, if all good you have a duff pump

lynall said:

Start simple, check relay is putting out power not just voltage but actual power, then check again at the plug on the pump, if all good you have a duff pump

Click to expand...

Sorry to be a pain, but could you describe that process. Thanks

edit: something like this?





I'm getting landy trailered back to me today and will give myself a week of tinkering before booking it in to a specialist

update.
ok, i got a proper look at all the fuses and relays. turns out its one of the engine fuses (the one that powers the fuel pump) keeps tripping. changed it, the pump primed (yipee!) got about half a mile up and down the street and the familiar flat spot happened. checked fuse, and its blown.
Could moisture in the fuel tank be causing this?
I've only 1/4 tank in it and feel this could be my next step.

defendermikey said:

update.
ok, i got a proper look at all the fuses and relays. turns out its one of the engine fuses (the one that powers the fuel pump) keeps tripping. changed it, the pump primed (yipee!) got about half a mile up and down the street and the familiar flat spot happened. checked fuse, and its blown.
Could moisture in the fuel tank be causing this?
I've only 1/4 tank in it and feel this could be my next step.View attachment 101782

Click to expand...

Have you checked the contacts at the pump itself? Check the plug fitted to the pump, if the contacts are brown (burned) or dirty, it would cause resistance and a higher draw, blowing the fuse. I did a Jaguar XK8 for a guy after the main dealer pushed it out the door telling him he needed a new engine!!! It was down on power too. I stripped the boot, got the pump out of the tank (what a mission) and the wires fitted to the pump (immersed in the tank) were white for a couple of inches, then brown where they had been overheating. The pump was original and clearly knackered. The draw must have been pretty high to cause them to burn.

Anyway, replaced the pump, fitted a new plug and boof, away she went like a scalded rat.

I would also check the wiring from the pump to the fuse block in case there is a dead short from chaffing on the body some where.

You could try a multimeter with amp setting, but most only go up to 10 amp, so no good for you.

Get a headlamp bulb and attach two wires to it with female spades one for each side of the fuse as you have a short it should light up when plugged in and ign on/engine running, have a play around unplug things etc until bulb out them you know you are in the right area, the pump should run albeit slower as the bulb will be robbing some of the power.

We do this at work to find elec faults mainly light circuits, the headlamp bulb is bright until you unplug the effect light unit with the direct short then the bulb goes out.

Intermittent wiring faults are by far the worst to find.

The other thing we used to do to find the really elusive fault, is to fit way to big a fuse and wait for the smoke to appear from the damaged/corroded wiring! sounds brutal but does work and can save hours.

You could of course supply your own power supply to the pump, if its cures it you know its the chassis wiring at fault

Doo said:

Have you checked the contacts at the pump itself? Check the plug fitted to the pump, if the contacts are brown (burned) or dirty, it would cause resistance and a higher draw, blowing the fuse. I did a Jaguar XK8 for a guy after the main dealer pushed it out the door telling him he needed a new engine!!! It was down on power too. I stripped the boot, got the pump out of the tank (what a mission) and the wires fitted to the pump (immersed in the tank) were white for a couple of inches, then brown where they had been overheating. The pump was original and clearly knackered. The draw must have been pretty high to cause them to burn.

Anyway, replaced the pump, fitted a new plug and boof, away she went like a scalded rat.

I would also check the wiring from the pump to the fuse block in case there is a dead short from chaffing on the body some where.

Click to expand...

Thanks a lot.
Yeah, I'm off to get a big bag of spare fuses as I will need them whilst I run through the possible causes
The nice guys that replaced my pump went in thru the tub so I've got a nice wee access hole to play about with, will inspect all the connections and trace all the lines back to fuse box. thanks, will keep you updated.

OK, been at it this afternoon and possibly getting closer to understanding the wiring.
Firstly the connections at the fuel pump. gave a good clean and a wiggle.
There are 4 wires.
Earth
Purple/white (12v live)
A thin green/black (terminates at ECU red plug)
A thin black/grey (terminates at ECU black plug)

I traced the electric lines out of the pump and they go into the rear crossmember, combine with the lighting electrics then get ferried inside the wheel arch box sections.
At the fuse box end, the purple/white live wire comes from the fuse holder, and into the left hand yellow relay. The same colour live wire exits the relay and combines with the rest and heads off under the seats, up beside the servo then into the fuse box on the lower dash. The cables that have already been through the drivers seat fuse box bypass this and head off to their own components. (apologies for being a bit layman over all this)
Now, before, the pump was priming and would start ok before the fuse blows.
Now, the fuse blows as soon as you turn the ignition to '2'.
I plugged in a bulb to the corresponding fuse slot for the fuel pump, and it stayed lit for 30 seconds before clicking off - the relay doing its job.
Whilst this was happening, I gave all the wires a good press to see if it was a short anywhere but nothing.
I then did the slightly naughty thing of hard wiring the fuse slot (only for a second or 2) to check the fuel pump was still working. Which it is, fine.

So, in my limited experience, this looks like an earth problem. Please correct me otherwise.
None of the other fuses under the drivers seat blow when I turn the ignition on, so that earth connection should be fine.
My main question, is would it be safe to give the fuel pump its own earth in situ onto the chassis to test this theory?

Many, many thanks for your patience and help guys.

a poor earth wouldnt exp[lain blowing fuses imo, a short in the feed wire or pump motor or blocked pump would

jamesmartin said:

a poor earth wouldnt exp[lain blowing fuses imo, a short in the feed wire or pump motor or blocked pump would

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ok, thanks.
this pump was fitted on friday and the old one exibited the same problems before it died. I've possibly been a bit hasty in replacing the pump, but hey, it worked fine for 50 miles before blowing fuses now (possibly what the old one did too).
So if it's a short in the live feed, I should be ok to create a new live feed for it from the wire that comes out of the relay?

thanks

jamesmartin said:

a poor earth wouldnt exp[lain blowing fuses imo, a short in the feed wire or pump motor or blocked pump would

Click to expand...

That sums it up, seems by working through the problem you have now narrowed the posibilitys so at least you can focus on the real issue rather than trying everything and hoping for the best.

defendermikey said:

ok, thanks.
this pump was fitted on friday and the old one exibited the same problems before it died. I've possibly been a bit hasty in replacing the pump, but hey, it worked fine for 50 miles before blowing fuses now (possibly what the old one did too).
So if it's a short in the live feed, I should be ok to create a new live feed for it from the wire that comes out of the relay?

thanks

Click to expand...

yes ,it would rule it in or out in any case

jamesmartin said:

yes ,it would rule it in or out in any case

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thanks mate.
I'll get on it later.

a question before I do it later, I don't have any auto cable lying about, could I use some single core off an old lawnmower as long as the rating/thickness is similar, just to test quickly?