Rough running Td5 Defender

Hi all,

I have a 2003 defender on just under 100k miles, a couple of days ago I went to overtake a slow moving vehicle and as I put my foot down there was hesitation and a lack of power. I pulled back in behind the car and noticed the engine was running very rough, possibly misfiring but I'm not sure.
It is rough at idle but gets worse under load, easing off and going smooth as you back off the accelerator, the problem is intermittent however.
My initial thoughts were fuel starvation for one reason or another.

Things I have checked for so:
No oil in ECU or plug
No fuel in oil
No fuel leaks
Air filter not blocked
Fuel filter not blocked

Things I'm looking at next:
MAF sensor - how would I test this?
Injector issue - still trying to find someone locally to read any fault codes.
Fuel pump - used to be noisy as hell but went silent about the same time as this issue, read that fuel could still be dragged through even if the pump is goosed, is there an easy way to test the pump without dropping the tank or cutting a hole in my load space?

Any other items at fault you guys could point me towards?

Cheers.

Hi, might be a fuel pressure issue, you can check the pump but you need a pressure gauge with the proper fitting and screw it instead of the FT sensor in the FPR, if no 4 bar there the pump's HP side is dead... to check the MAF unplug it and go for a ride this way, if it's better it means the MAF is gone... do you have EGR?, if yes it can be clogged as well and the MAP sensor full of gunk.... the best way though would be to connect a dedicated tester.

Thanks for the reply, EGR is blanked. Will definitely take it for a spin with MAF sensor disconnected, see what happens. I might have a pressure gauge at work that I could rig up.

armourermark said:

Thanks for the reply, EGR is blanked. Will definitely take it for a spin with MAF sensor disconnected, see what happens. I might have a pressure gauge at work that I could rig up.

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with the maf sensor disconnected you may have a 20 to 30 second delay until the ECU goes into a set limit

if the fuel pump has been screaming more than likely the fuel system has combustion gasses ..mine screamed for about 4 months maybe more once i changed the combustion washers i felt like it was sluggish . the gauze filter in side the head will be chocked with carbon

to be honest cutting a hole might be easier way then make a plate to cover ....this then can be easily made as inspection hole nothing worse than dropping the fuel tank to clean or change parts when there is no inspection hole

the fuel pump sits inside a housing this also has a screen on the bottom that could be clogged
and no the engine will not pull the fuel through on its own the injectors need some sort of pressure to run ..your going to need to measure pump pressure and head pressure

ps how sure are you the fuel filter is not blocked ? the filter media inside the fuel filter also turns black when carbon enters the fuel system

also i know the EGR has been blanked off but this doesn't stop old residue from moving due heat soak inside the inlet manifold ..clogging up the MAP sensor

The EGR was actually blanked from manufacture as it's a NZ model.
I took the fuel filter off and had a quick look inside, just looking for diesel bug really, might swap the filter anyway. I'll also remove the FPR to access the gauze filter.
The pump used to whine a bit but a few days before this happened it started making more of a grinding noise, now it's silent...

before doing the FPR filter make sure you have a new gasket ready
the fuel pump screaming indicates to either combustion gasses or a fuel blockage the fuel filter housing will need some attention also as there are also a few things that can clog up
now the pump has gone silent the pump has now lost performance but enough to keep the engine running
this would indicate a miss on the engine

best to clean fuel tank filter housing and change fuel filter then run some pressure checks before purchasing a new pump

Thanks for that, more fault finding today.
Anyone know what size thread the FT sensor is? I've seen a few pressure testers for sale fairly cheap.

M12 x 1.5

Change the injector harness.
Ours did this and it seemed to be only running on 4 cylinders....happened without warning.
There was no oil in the ECU plug but after changing the injector harness it was fine, and the fault never recurred.
Definitely worth a try at only £25 for the part, and half an hour to fit.

I changed the injector harness only 2 months ago, used OEM, unfortunately they cost around $140 here (approx £70) hopefully that hasn't crapped out already.

armourermark said:

Thanks for that, more fault finding today.
Anyone know what size thread the FT sensor is? I've seen a few pressure testers for sale fairly cheap.

Click to expand...

depending what results you get when doing a pressure check ..if the fuel regulator has lost its performance or jammed up in the open position
the fuel pump will also loose pressure you will have flow but very little pressure ( this is why its called a fuel regulator )
you could try and restrict the return fuel line to see if the pressure changes also take note of sound of pump

to test.... a set of vise grips clamping on the fuel return fuel line ...only enough to create or manipulate a restriction to allow the fuel pump see a load

seirraferry may be right about the stage in the pump failing.... but I would try and load it up first just in case its something silly like a blockage or an open fuel circuit

Well I went for a drive earlier to get any fault codes read, only made it a few kms from my house before it completely died, it would turn over but not start so it pretty much confirmed the fuel pump at fault.
Walked back home, picked up the wife's car and a bunch of tools, bought a new pump from a local landy specialist then knocked on the door of the house I'd broken down in front of to ask if I could borrow some electricity.
Nice guy had no problem with me doing that, and even made me a cuppa! Two and a half hours later new pump installed, ran the self prime thingy and it started and ran perfect. Just got a great bloody hole in the floor now!

The hole!

Nice, You found it on the first attempt.

Very useful for future use....

A bit of ally, sealant and a rivets or 4. Job done.

Cheers

armourermark said:

Well I went for a drive earlier to get any fault codes read, only made it a few kms from my house before it completely died, it would turn over but not start so it pretty much confirmed the fuel pump at fault.
Walked back home, picked up the wife's car and a bunch of tools, bought a new pump from a local landy specialist then knocked on the door of the house I'd broken down in front of to ask if I could borrow some electricity.
Nice guy had no problem with me doing that, and even made me a cuppa! Two and a half hours later new pump installed, ran the self prime thingy and it started and ran perfect. Just got a great bloody hole in the floor now!

Click to expand...

glad you got it running ..with out pressure checking
cutting a hole in the floor is last of your worry's this gives you time to make your own inspection plate no big deal and not the end of the world
the inspection plate will come in handy for other issues in the near future
you need to ask why was the first fuel pump screaming like a cat in the first place ..also take note of the temps of the return fuel back to tank

I wonder if the pump was noisy because it was on its way out? Time to dismantle it!

worn out injector washers cause combustion gasses to get into the fuel side. This then kills the pump.
I changed a pump then months later a 2nd died.

The cause was worn copper injector washers

Cheers, how would I test for combustion gasses getting into the fuel? Just look for carbon build in the filter?

other things to look for is return fuel temp .

heat also kills fuel pumps .my fuel cooler thermostat had failed fuel tank and filter would reach up to 60 to 70 degrees on long drives

I took the pump apart and found that one of the motor's spring loaded bushes was a lot shorter than the other and had caused a lot of carbon build up on the commutator.