Lumpy 10p TD5 - D90

My son's D90 TD5 has just developed a very lumpy tickover. Any attempt to drive it more than 10 yards and very lumpy graduates to really, really unpleasant and a slow limp back. It starts first time and sometimes seems fine until you try to rev the engine at which point it goes back to a lumpy idle.

Their are no DTCs. There is no oil in the ECU red plug, and changing the injector loom this afternoon made no difference. As an aside the outgoing loom was a Bearmach one fitted 3 years ago and the plug under the rocker cover was dry as a bone. I might clean it and keep as a spare.

When it starts and runs fine the idle is solid at 745-750 and the roughness on all 5 injectors is no more than +/- 2. As soon as it goes lumpy the idle is a bit less stable and individual injectors can be up to +/- 20.

I have not yet checked the fuel pressure, but the fact that the engine starts means that the fuel pump is still delivering 4 bar at idle. However, it can no longer be heard. It cannot be heard before start even if running the auto priming system. The MIL flashes correctly, but no whine at all from the pump - nor any sound of air in the fuel.

The obvious conclusion is that the fuel pump is barely coping and needs to be replaced. Does the collective agree, or is there another possibility I have not thought of?

Does sound like a fuel pump issue. I had intermittent lumpy running which was cured with a new in tank fuel pump. Luckily it was still under warranty then.

Thanks, I think when the tank is dropped a full flush of the system would be sensible as well.

This happened to our TD5 90 and it was the injector harness.
The Land Rover was clearly running on four cylinders, l fitted a new injector harness and had no further trouble with it.
Worth a try.
Note there was no oil at the red plug on the ECU

lightning said:

This happened to our TD5 90 and it was the injector harness.
The Land Rover was clearly running on four cylinders, l fitted a new injector harness and had no further trouble with it.
Worth a try.
Note there was no oil at the red plug on the ECU

Click to expand...

That was our first thought too. No oil on Red plug, no oil on the plug under the rocker cover, but we swapped out the injector harness anyway - no change. When it is lumpy the roughness is not always on the same cylinders, but seems to be a different pattern every time it starts.