Description of My Diesel Cold Start Issue

Paddy (Thats my Pajeros Name) developed its intermitting cold start issue around Feburary 2008. Its inital issue was that it would start pefectly but after about 10 - 20 sec the engine would run "lumpy" like one or more of its cylinders was not getting fuel or heated enough, and there was moderate amount of smoke coming out the exhaust. With a little increase of the engine RPM to about 1500-2000 the lumpiness would work itself clear and the engine would run fine. Once the car had past its first start of the morning, ever other engine start was perfect and no sign of the lumpiness.

But the intermitting issue became more persistant (as anything would do if it does not get fixed) and eventually even upping the RPMs to 2000-2500 would not help and the engine would simply stall and there was a shit load of smoke coming out of the exhaust during the lumpiness. The restart would take a fair bit of cranking, once started a little lumpy then all was good.

I jumped onto the Pajero 4WD Club of Victoria Forum and started the following thread "NJ TDi 2.8 Strange Start issue" This thread started expanding my knowledge of diesel cold start issues alot. After some very help advice, I followed some advice regarding air in the fuel system and I bled the system the cold start issue disappeared. And so let my guard down and thought I had won.... but only after about 3-4 weeks, it came back with avengence.

During my initial investigation when trying to work out what was happening I decided to do the following test to see what would happen. I started the engine and raced round to the fuel filter / primer and just as the engine started to run lumpy I pumped the primer a few pumps and the engine ran smooth. Then starting lumpy again so I repeated this process 6-7 times and then the engine ran fine. And as usual all other engine starts during the day, the engine started and ran without any hiccups.

This same initial test was the only process that would stop the Pajero Diesel enigne stalling during cold start so it meant I still had an issue with my fuel system. This started me down my path of researching and attempting to gain a better understanding of diesel fuel systems.

Please bear with me as I start doing a brain dump of what I've learnt and think I've understood. Then I'll start to expand on each sympton and tests and details as I have time. Over time with with your feedback, hopefully we'll have a nice little knowledge repository top cope with "Diesel Cold Start Issues".