This is abit of along one so stick with me guys,

Been having issues recently with my '55 plate TD6 (122,000 miles), turning over and not firing have done a few fixes each seeming to have solved the issue only for it to reappear again, main symptom is engne turning over at normal speed but not firing, this is only intermittent however.

1st failure was intermittent starting but a smack on the EGR valve got it going, removed EGR valve and it looked to be stuck open, which I know can cause starting issues on some diesel engines so fitted bypass kit and all was well.

2nd failure (symptoms the same) removed fuel pipe from fuel filter to engine and no fuel, pipe in had fuel on removal so replaced fuel filter, took awhile to get diesel through but it eventually filled, FF started and problem disappeared.

3rd failure, same symptoms, put jump leads on to keep what was an old battery charged and whilst investigating and car started straight away, fitted a Bosch S4 battery now and problem went away.

5th failure, again same symptoms, tried to start with "easy start" and it ran on that then cut out, hit secondary fuel pump with hammer and it ran, so replaced secondary fuel pump and it ran fine.

6th failure, again same symptoms, but it starts off a little easy start and runs fine, nice and quiet.

Now the weird thing is I can go from Home in the Falkirk area to Glasgow and it will stop and start no issues but if I have been jumping in and out of shops on short journeys it seems to present itself. I was thinking I may have some cedement or crap of some sort in my tank as a couple of the issues have been fuel feed related, so I've put some Wynns Extreme Diesel treatment in today incase something s clogging the system causing a pressure problem on starting.

Like I said, it's turning over and not firing, crank speed is normal, a weird little gremlin which goes away after something is changed on to creep p when least needed.

Was wondering if anyone had experienced anything like this before as I'm starting to go mad with it '55 Java Black Vogue

I think you may need to change your secondary fuel pump.

It was the secondary pump that I replaced under the N/S/R wheel. That's why I'm thinking something causing a pressure loss in the fuel system and going for a fuel system cleaner and probably a few tanks of Ultimate diesel afterwards. '55 Java Black Vogue

It sounds as though you have a faulty injector. You need to have an injector leak off test carried out to determine which (indeed, if any) injectors are at fault

Thanks Mikey,

I did consider an injector fault and should have the kit lying around to do an injector test. However there is one thing that doesn't make sense and hopefully a man with your expertise or someone else could clear it up.

Before the secondary fuel pump was replaced, the car was turning over and would only catch then instantly cut out if easy start was used, just like if it had ran out of fuel or wasn't fuelling at all this only changed when the pump was battered with a rubber mallet and then replaced.

the car will start 99% of the time now and if easy start is used fault will clear instantly, car is running smooth and silent and even returning 25-28mpg on motorways. From what I've read it is normally the sealing element between the LP and Hp side of the injector that is at fault and causes the injector failure, wold this not be a permanent fail meaning that the problem would constantly be present and not intermittent?

Is it possible that low pressure could be caused by a partial blocking of the high pressure side of the injector from something dislodged in the fuel pump when I battered it with a mallet? '55 Java Black Vogue

As you have changed the secondary fuel pump, presumably for a reputable make, have you considered the fuel pump relay causing problems. The fuel pump relay is located on the rear fuse board and serves both the intank fuel pump and the secondary fuel pump. It might be worth swapping the relay to see what happens.

I've got a spare LR relay in the car, which relay is it exactly don't have an owners book to help out so will swap it out for testings sake but it seems like there is fuel, just a pressure issue, unless there is some sort of strange resistance issue in the relay not allowing enough power to the pump to maximise pressure???

It was a Pierburg Pump as per BMW's original installation. '55 Java Black Vogue

If the relay is at fault i would suspect burnt contacts, they don't last for ever.