Rover 75 CDTi - Non-starting problem
 

Hello all,

I'm after a bit of help please as I'm struggling to diagnose a non-starting issue on my 75.

It's a 2003 CDTi Manual Classic SE with about 72,000 miles and has been off the road since 2018. I bought it as a non-starter and diagnosed the issue as a failed in-tank fuel pump. I replaced the pump and the car started, ran and drove around on several occasions. I did have one or two hesitant starts though.

Idle was lumpy so I cleaned out the EGR valve and intake manifold as both were heavily coated with soot. It seemed to idle nicely after this (may have been coincidence?) and I ran it on 3 or 4 occasions without issue.

I then replaced the radio and since then, it has refused to start. The engine turns over on the starter and occasionally coughs but no more than that. I've been following FrenchMike's instructions to try and diagnose the issue:
https://www.the75andztclub.co.uk/for...ad.php?t=69308
https://www.the75andztclub.co.uk/for...d.php?t=109615

Voltage at the low-pressure fuel sensor measured 3.82V before a fuel filter change and 3.80V after. This is slightly below the 3.9V mentioned in the 'How To' but is above the 2.6V minimum I read in another post. The under-bonnet pump is a bit noisy but flow appears to be good when I disconnected the outlet from the filter and the voltage readings seem to back this up. I listened for the in-tank pump and I can hear it running.

The cam sensor gave a 12V reading, dropping to 0V when a metal object (socket) was waved in front of it.

The high-pressure fuel sensor gave a 0.5V reading when priming the fuel system but only rose to around 0.7V when cranking the engine over, the target in the 'How To' is 1.2V. I found that if I primed the fuel system several times before attempting a start, I would briefly get a reading of 0.9V when cranking and the engine would cough and run for maybe half a second before dying and falling back to around 0.7V.

I performed a leak off test on the injectors expecting one or more of them to show an obvious problem, but this is where I'm struggling. Having never done this before, I don't know what "normal" looks like. Number 2 (going from left to right) seemed to leak the most, followed by 3 but it didn't look that bad to my untrained eye. I would guess about 2 or 3ml from about 20s of cranking. I recorded a video which is here: https://youtu.be/E2JthP0jTUs

Does anyone know if this is sufficient leak off the prevent it starting?

If it isn't, are there any suggestions as to what I should look at next? Would clogged injectors result in a low pressure (voltage) reading? I didn't think so but I'm not experienced in diesel injection systems. I'm thinking other possible candidates are: high-pressure pump, high-pressure fuel sensor or fuel pressure regulator.

I tried a squirt of Easy-Start in the EGR valve and it briefly fired up on this but died. I'm reluctant to use it again though as it sounded awful.

Thanks for your help,
Matt

Hi, change the fuel filter, and spray the electrical connector on the regulator on top of it with electric contact cleaner, also take a look at the HP pump regulator seals, how much fuel is there in tank?.

Thanks for your help. I've already changed the fuel filter but hadn't thought to clean the electrical contacts so will give that a go. There's between 1/4 and 1/2 a tank of fuel. I'll also take a better look at the HP pump and regulator.

One other thing to check is the rev counter needle when cranking the engine. If the needles twitches or moves a little it means the crancksenor is fine, if not then it will need replacing as this sensor is important for starting the engine

The rev counter needle rises and bounces around 100rpm when cranking, so I believe the crank sensor is OK.

I've tried cleaning the electrical connections to the fuel pressure sensors, cam sensor and regulator but no joy.

I tried using Easy Start twice more and both times it started briefly and then died. I'm beginning to suspect either a regulator or HP pump issue but need to figure out how to narrow it down further.

Thanks

Hi Mat.
Have you checked the plenums for water or any tell tale signs of tide marks if it had been standing for a few years, have you checked the ECU for damp inside etc, maybe worth a look, just to make sure.

Sorry I should've mentioned this in my initial post. First thing I did when I bought the car was check and clear the plenum drains. When the car wouldn't start, I re-checked the plenums and they were dry and the drains were still clear. I'll take another closer look at the ECU for evidence of previous water ingress.

Matt when you checked them was water present in the plenums, and have you opened the ECU to take a look, it's not hard to do once you have it on the bench.

When I first checked the plenums, there was no water or at least very very little. I'll take the ECU out and have a good look. Where the car was stood it wasn't near any trees and I don't recall there being any great amount of debris in the plenum, but definitely worth double checking the ECU as you've suggested. Thanks

Looking at the results of your FrenchMike tests, it looks to me that you are not getting the correct pressure from the HP pump, for the fuel to ignite. So I would be concentrating on the HP regulator seals/flange, I wouldn't be surprised if one of the sealing rings is had it.
Good luck.