welloiled · Apr 21, 2020

Hi all, I'm hoping to pick the brains of the boffins. My defender 2.4 has been giving two main problems, engine surging intermittently between 2500/3000 rpm and revs dropping away ie when you bring the revs up in neutral and hold the pedal steady they can fall away by around 1000 rpm. I've replaced and checked/had tested the following
1 injectors 100%
2 fuel rail replaced with genuine new LR rail and sensors
3 MAP sensor replaced
4 MAF sensor replaced
5 VCV replaced with hp pump relearn
6 New MAN fuel filter
7 Inlet manifold gaskets replaced
8 Fuel tank inspection - clear
9 Fuel sender unit good
10 ECU relay swapped
11 Remap with EGR delete and blank plate
12 HP fuel pump good
I did notice a slight weep mist on the intercooler at the hose connection but the hose was in tact. Have a new LR intercooler on route.
Any ideas would be much appreciated as I'm not sure if this could be an intercooler issue. No black smoke etc. Thanks in advance.

welloiled · Apr 21, 2020

Any thoughts anyone, could really user some help. Thanks.

lynall · Apr 22, 2020

Can you see live date on fuel pressure?
I ask as we are having shed loads of fuel issues at work due to skanky derv that has been going around for 6mths at least.
Is there a test nipple so you can manually check fuel pressure before the hpfp?

Assumimg it has an intank pump has the intank pump got a filter screen around it?
I had a td5 that used to block the screens often.

Have you checked the cam timing? I know this engine in the transit used to have troubles with the timing chain tensioner and chain wrap on the pulleys.

Generally you will find theres not to much knowlegde on here for the tdci, it will come, but at the minute they are to new for the majority of folk.

welloiled · Apr 23, 2020

Hi lynall, thanks for your response;
The live fuel pressure data was good although I haven't tested it pre hpfp, will check.
I use BP Ultimate Diesel from a very busy station (and MAN filters), so fuel quality should be on the money.
There is just a sender unit in the tank which I accessed via a cut hatch in the back to avoid dropping the tank, inside was immaculate. I split the old fuel filter too which was clean.
I'm pretty sure the hpfp uses a vacuum not a pump in the Puma's.
I haven't checked the cam timing as the engine sounds good, will look into this.
Cheers again

Scooby22 · Apr 23, 2020

Sounds like air leak problem, check all air hoses and manifold gaskets for leaks, as well as fuel lines but more likely the air side.

Wimblowdriver · Apr 23, 2020

welloiled said:
I'm not sure if this could be an intercooler issue

The intercooler is a weak point and the plastic inlet and outlet boxes can separate from the metal core. But any loss of boost pressure will normally throw up a fault code, engine management light on and limp mode. Looking at your list I would take a look at the throttle position sensor on the pedal. I would also clear the ECU of all fault codes to eliminate old / fixed issues, go for a run and then get any new fault codes. Not all fault codes will show an engine management light. If no fault codes show and there is still a problem, I would enquire if there were any software updates which are outstanding.

lynall · Apr 23, 2020

welloiled said:
Hi lynall, thanks for your response;
The live fuel pressure data was good although I haven't tested it pre hpfp, will check.
I use BP Ultimate Diesel from a very busy station (and MAN filters), so fuel quality should be on the money.
There is just a sender unit in the tank which I accessed via a cut hatch in the back to avoid dropping the tank, inside was immaculate. I split the old fuel filter too which was clean.
I'm pretty sure the hpfp uses a vacuum not a pump in the Puma's.
I haven't checked the cam timing as the engine sounds good, will look into this.
Cheers again

We use 1000s of litres per day at work (150 trucks) and are having to change the filters every 8 weeks, but that doesnt sound like your problem.
Strange it does not have an intank or inline pump I would have thought low fuel pressure or air getting into the hpfp could cause trouble.
Other odd thing I have seen on trucks is a porous filter head, no extenral signs of failure, but new head cured it.

Fuel pipes jubilee clip type, or them nice push on ones?
If push on have you checked the internal o-rings

Wimblowdriver · Apr 23, 2020

Some reading attached for the tdci fuel pump / how it works. I do know that the pump self bleeds and is tolerant to small amounts of air getting into the system.

lynall · Apr 23, 2020

Transfer pump internal to the hpfp is a new one on me.

As mentioned above it would seem like you are pulling air in from somewhere, maybe more than the system can handle.

I do not know what filter set up the car has, but can remember transits having some daft push on filter with a clamp around the outside? not fitted correctly caused running issues.

Wimblowdriver · Apr 23, 2020

Fuel filter canister is removed by turning 1/4 or 1/2 turn or thereabouts and pulling down (just like a light bulb). Fitting is filling with fuel which lubes the internal seals, offering to the filter head and lining up the "pips", push up and turn to lock in place. Air has to be purged out using a hand pump on the fuel line, near the fuel pump via one of the pipe connectors - this gets out most of the air as a bit gets back in when re-making the connection. Run the engine and the pump completes the purge.

lynall · Apr 23, 2020

Wimblowdriver said:
Fuel filter canister is removed by turning 1/4 or 1/2 turn or thereabouts and pulling down (just like a light bulb). Fitting is filling with fuel which lubes the internal seals, offering to the filter head and lining up the "pips", push up and turn to lock in place. Air has to be purged out using a hand pump on the fuel line, near the fuel pump via one of the pipe connectors - this gets out most of the air as a bit gets back in when re-making the connection. Run the engine and the pump completes the purge.

I am findng at work that the diesel does not lubricate the filers seal enough, and they can snag/twist stopping the filter seating correctly, same on all the makes of trucks.
In my mind the lubricity of diesel has changed over the last 2 maybe 3 years.

Everyone else must ba having the same issue as every filter I now remove has traces of grease on the threads/clamp/seals.

Wimblowdriver · Apr 23, 2020

lynall said:
Everyone else must ba having the same issue as every filter I now remove has traces of grease on the threads/clamp/seals.

I'll bear that in mind next filter change. Last time I didn't put grease on the seals because I thought it would dissolve as soon as I filled it with diesel. Maybe put the grease on the spigot.

lynall · Apr 23, 2020

Wimblowdriver said:
I'll bear that in mind next filter change. Last time I didn't put grease on the seals because I thought it would dissolve as soon as I filled it with diesel. Maybe put the grease on the spigot.

Most of ours are the plastic cap filters housings, I am now greasing all of them metal and plastic, used to just add a smear of oil from the drianer onto the seal, but that doesnt seem to be enough these days.

Wimblowdriver · Apr 23, 2020

The tdci filter housing is plastic but I can't remember if the spigot that goes into the filter is metal or plastic. It will be a while before it gets changed again.

lynall · Apr 24, 2020

Cummins filters last night, last bloke didnt grease them, fcuker!

welloiled · Apr 27, 2020

Scooby22 said:
Sounds like air leak problem, check all air hoses and manifold gaskets for leaks, as well as fuel lines but more likely the air side.

Thanks, I'll follow up

welloiled · Apr 27, 2020

Wimblowdriver said:
Some reading attached for the tdci fuel pump / how it works. I do know that the pump self bleeds and is tolerant to small amounts of air getting into the system.

much appreciated, some good info

welloiled · Apr 27, 2020

Wimblowdriver said:
The intercooler is a weak point and the plastic inlet and outlet boxes can separate from the metal core. But any loss of boost pressure will normally throw up a fault code, engine management light on and limp mode. Looking at your list I would take a look at the throttle position sensor on the pedal. I would also clear the ECU of all fault codes to eliminate old / fixed issues, go for a run and then get any new fault codes. Not all fault codes will show an engine management light. If no fault codes show and there is still a problem, I would enquire if there were any software updates which are outstanding.

Hi, intercooler changed out and still intermittent surging, maybe not just as bad, I also changed the ring seal between the inlet manifold and the EGR exit which debateably made things a bit better.
The TPS requires a new pedal I think so I'm keen to avoid anymore expense and pursue air/fuel line leaks. thanks again

welloiled · Apr 27, 2020

lynall said:
I am findng at work that the diesel does not lubricate the filers seal enough, and they can snag/twist stopping the filter seating correctly, same on all the makes of trucks.
In my mind the lubricity of diesel has changed over the last 2 maybe 3 years.

Everyone else must ba having the same issue as every filter I now remove has traces of grease on the threads/clamp/seals.

It's a good point to check up, would be nice if this cured it, cheers

saxosportsaxo · May 3, 2024

Sorry to dig up an old thread but i'm having this issue... Did you resolve it? Mine is doing this exact fault and i have changed everything you have done.. Please help

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