Rover 75/ MG ZT CDTi not starting

bassmanham · 29th May 2013, 17:37

After years of using this forum to keep my cars running I thought it was time to contribute and maybe help shorten the pains of somebody with the dreaded diesel not starting problem.

My ZT was running and starting fine until it suddenly began having problems firing.
The engine would turn but not fire.
My tale of woe then went on for a couple of months.

Reading the forum suggestions I decided it was the in tank pump so replaced it. That made no difference.
I noticed a whooshing noise coming from the diesel high pressure pump when turning on the ignition key but not turning over the engine so I wondered if air was being pumped into it.
Fuel was pumping out of the under bonnet pump with a fair pressure but I did notice it looked aerated. After following that red herring for a while I now believe that was caused by the under bonnet pump sucking faster than the in tank pump can push.

During all this attempted starting I decided the battery had failed so replaced that (I now have a perfectly good spare battery) and the starter motor solenoid contacts burnt out so I replaced them.

Somehow after all this the car was starting ok but no explanation why.

Until it stopped starting ok and would only start with easy start. After starting it ran fine.

After more forum trawling I found FrennchMikes description of how to measure low and high fuel pressures. http://www.the75andztclub.co.uk/foru...ad.php?t=69308

My low pressure was fine but the high pressure never went past 0.6v showing I had a high pressure leak. Resisting the urge to send off the injectors for service I tried a leakback test which showed no fuel leaking back when cranking (I now know there was no leakback because there was no fuel pressure to cause them to leak).
All the joints were tight with no apparent fuel leaking. Then I found mention of the high pressure regulator solenoid.
I removed the regulator solenoid which is bolted to the high pressure pump by two hex bolts and voila a destroyed ‘O’ ring fell out.

A picture of said failed part should go here but I cannot work out how to post it.

The regulator is easy to remove after removing the plastic inlet manifold.

A repair kit CMR1700-9 was ordered from http://www.darwendiesels.com for the princely sum of £2.60 and now fitted the car starts first time every time.

Bit of a long story I know but it was longer in real time. Hope it helps somebody.
Many thanks to FrenchMike for the fuel pressure diagnostics guide.

29th May 2013, 17:37	#1
bassmanham Newbie MG ZT Join Date: May 2013 Location: London Posts: 1 Thanks: 0 Thanked 2 Times in 1 Post	Rover 75/ MG ZT CDTi not starting After years of using this forum to keep my cars running I thought it was time to contribute and maybe help shorten the pains of somebody with the dreaded diesel not starting problem. My ZT was running and starting fine until it suddenly began having problems firing. The engine would turn but not fire. My tale of woe then went on for a couple of months. Reading the forum suggestions I decided it was the in tank pump so replaced it. That made no difference. I noticed a whooshing noise coming from the diesel high pressure pump when turning on the ignition key but not turning over the engine so I wondered if air was being pumped into it. Fuel was pumping out of the under bonnet pump with a fair pressure but I did notice it looked aerated. After following that red herring for a while I now believe that was caused by the under bonnet pump sucking faster than the in tank pump can push. During all this attempted starting I decided the battery had failed so replaced that (I now have a perfectly good spare battery) and the starter motor solenoid contacts burnt out so I replaced them. Somehow after all this the car was starting ok but no explanation why. Until it stopped starting ok and would only start with easy start. After starting it ran fine. After more forum trawling I found FrennchMikes description of how to measure low and high fuel pressures. http://www.the75andztclub.co.uk/foru...ad.php?t=69308 My low pressure was fine but the high pressure never went past 0.6v showing I had a high pressure leak. Resisting the urge to send off the injectors for service I tried a leakback test which showed no fuel leaking back when cranking (I now know there was no leakback because there was no fuel pressure to cause them to leak). All the joints were tight with no apparent fuel leaking. Then I found mention of the high pressure regulator solenoid. I removed the regulator solenoid which is bolted to the high pressure pump by two hex bolts and voila a destroyed ‘O’ ring fell out. A picture of said failed part should go here but I cannot work out how to post it. The regulator is easy to remove after removing the plastic inlet manifold. A repair kit CMR1700-9 was ordered from http://www.darwendiesels.com for the princely sum of £2.60 and now fitted the car starts first time every time. Bit of a long story I know but it was longer in real time. Hope it helps somebody. Many thanks to FrenchMike for the fuel pressure diagnostics guide.