Disco 4 (LR4) Changed inlet manifold - now won't start

Hi Folks,

I have just changed the driver's side inlet manifold on my 2011 Disco 4 3.0L TDV6 due to it splitting.
During the job I did a bit of damage. The plastic connectors for the injector return lines were brittle as hell so broke apart as I removed them. I replaced the right hand set of return lines with rubber hose (couldn't see why I should spend £100 on a new set for both sides). Also managed to damage the connector for the fuel rail pressure sensor so replaced that.

The issue now is that the vehicle won't start. It cranks for a few seconds, starts for a moment and then cuts out after about 3 seconds. I have noticed that the rubber hoses I added to replace the return lines were rock hard and seemingly under pressure. I didn't think they would be at much pressure at all.

There's nothing showing up on my cheapo OBD tool.

Any ideas? Be nice to try something myself before getting it over to a garage.

Cheers

Iirc the return lines for both heads are in fact one unit, they also have a non return valve which holds residual pressure when the engine is off, something silly like 10 bar?

Search for LR032107

sloth1 said:

During the job I did a bit of damage.

Click to expand...

sloth1 said:

The plastic connectors for the injector return lines were brittle as hell so broke apart as I removed them. I replaced the right hand set of return lines with rubber hose (couldn't see why I should spend £100 on a new set for both sides).

Click to expand...

They shouldn't be brittle in a few year's, so were you using the correct removal technique?

sloth1 said:

Also managed to damage the connector for the fuel rail pressure sensor so replaced that.

Click to expand...

sloth1 said:

The issue now is that the vehicle won't start. It cranks for a few seconds, starts for a moment and then cuts out after about 3 seconds. I have noticed that the rubber hoses I added to replace the return lines were rock hard and seemingly under pressure. I didn't think they would be at much pressure at all.

Click to expand...

That's because the spill lines aren't spill lines like in old injector designs. These injectors used a pressurised auxiliary line (looks like a spill line), which forms part of the hydraulic link system in the injectors. Unless the auxiliary line is pressurised to around 10 Bar (147 PSI), the injectors can't work, as there's insufficient hydraulic pressure for the valve to lift off the seat, which prevents the injector from spraying.

Nodge68 said:

Click to expand...

Agreed.

Nodge68 said:

They shouldn't be brittle in a few year's, so were you using the correct removal technique?

Click to expand...

Yeah I pulled the locking sleeve up but some of the four plastic 'prongs' which grip the nipple snapped off.

Nodge68 said:

Click to expand...

Agreed.

Nodge68 said:

That's because the spill lines aren't spill lines like in old injector designs. These injectors used a pressurised auxiliary line (looks like a spill line), which forms part of the hydraulic link system in the injectors. Unless the auxiliary line is pressurised to around 10 Bar (147 PSI), the injectors can't work, as there's insufficient hydraulic pressure for the valve to lift off the seat, which prevents the injector from spraying.

Click to expand...

That's interesting information, thanks. I will just have to get the proper part and give it a go. Hopefully that's all that's stopping the car from starting and running properly.

Welcome to the forum.