CDTI struggles over 2000 RPM

[Geoff130]

Thanks Mike, they do run for about a minute, it does seem longer until you time it.

[Rover 75 Tourer]

Fuel pressure sensor at the back of the high pressure pump caused a simlar problem on one of my tourers. Starter motor off job in order to remove the two small bolts holding the sensor on.Try a second hand unit if you can new ones a bit expensive if I remember right.

[Geoff130]

This seems to be getting worse and has took a couple of attempts to start recently. I'm have about half a tank of fuel since adding a bottle of Forte diesel treatment. I've rechecked and the low pressure has now dropped from over 3 Bar to around 2 at idle and barely one when attempting to rev. I can feel strong pulses and hear the under bonnet pump easily. The in tank pump makes a noise but is extremely quiet. I've now got it halfway out to check it and got to the point where Rave says to drain the tank. Is there an easier way?

[marinabrian]

Originally Posted by Geoff130

This seems to be getting worse and has took a couple of attempts to start recently. I'm have about half a tank of fuel since adding a bottle of Forte diesel treatment. I've rechecked and the low pressure has now dropped from over 3 Bar to around 2 at idle and barely one when attempting to rev. I can feel strong pulses and hear the under bonnet pump easily. The in tank pump makes a noise but is extremely quiet. I've now got it halfway out to check it and got to the point where Rave says to drain the tank. Is there an easier way?

Yes, put it back in, the problem isn't likely to be in the tank

If the LP drops when the priming valve is covered in the case of an in tenk pump that has failed, the problem is at the front end

So as you have 1/2 a tank of fuel in the car, the valve on the in tank pump is covered, and so even if it's goosed the car will run fine without it.

Your original fault was due to a defective FP relay, did you open it up to see if it was full of diesel as I suggested, and have you changed the fuel filter also, as well as checking the pump isn't leaking around the connector?


Brian

[Geoff130]

Thanks Brian, I'll pull the old relay apart in the morning. Everything around the under bonnet pump looks dry but I'll check it again in the daylight. I replaced the filter last week.

[Geoff130]

As you said Brian, the ITP is fine, there was a break in one of the wires from the LP sensor about 2mm from the connector with corrosion inside the insulation, no diesel in the relay though. It's now great up to just over 3000 RPM. I think there's still a faulty sensor or connector somewhere.

[marinabrian]

Originally Posted by Geoff130

As you said Brian, the ITP is fine, there was a break in one of the wires from the LP sensor about 2mm from the connector with corrosion inside the insulation, no diesel in the relay though. It's now great up to just over 3000 RPM. I think there's still a faulty sensor or connector somewhere.

I don't know whether you can look at the live data while the car is being driven Geoff, that's normally how I diagnose in the passenger seat of course.

Brian

[Geoff130]

I can get the wife to drive next time we need shopping, I can check the live data then, I only have TOAF though not a T4.

[marinabrian]

Originally Posted by Geoff130

I can get the wife to drive next time we need shopping, I can check the live data then, I only have TOAF though not a T4.

It's only the LP figures with the engine under load you really need Geoff

Brian

[Geoff130]

I think I'm beginning to get the message, a trip to the shops showed the low pressure falling from 3.2 Bar down to 1.7 Bar under load. Reading the faults that were clear before I set off there were 18 counts of reduction due to low pressure. At 182,600 miles, is my under bonnet fuel pump a little tired.