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Discussion Starter · #1 ·
A friend went home yesterday and parked his car and came out this morning and its turning over but wont fire

Its a 525 diesel and i will be taking a look at it on monday

The imobiliser is fine and glow plugs are fresh so i can rule them out

Any pointers or known problems would be very much appreciated
 

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Start with fuel delivery. When ignition is turned on you should be able to hear the electric fuel pumps (both in tank and under the left passenger seat) delivering fuel from tank to the mechanically driven high pressure pump via the fuel filter. These pumps will time out after about 30 seconds irrespective of whether engine was started or not. It might be simply a blown fuse for the electric pumps or could be a faulty electric pump.
If the fuel tank is low on fuel, problems with the low pressure supply pumps cause airlocks and starting difficultys. Keeping the tank topped up to a minimum of a little over half full will help with starting. If the electric pump under the passenger seat is OK and the in tank pump is faulty, turn on the ignition for about 20 seconds to run the electric pump. This will bleed the system and once the 20 seconds is up (dont turn the key off) just turn the key to the start engine position.
 

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most likely fuel related as said, i have had them with the pump running but low pressure - reckon the impeller has come adrift. you should have about 3.75 bar presupply pressure. if no faults are present ie; crank/cam. i'd do a leak off test on the injectors, if youv'e got a heavy leak on one it won't allow it to start.
 

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Discussion Starter · #4 ·
Checked pump in tank today and it was not working at all so off i went got a new pump and fitted it pump is now working but car still wont start

Is there any special tricks to bleeding theese
 

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Alot of modern diesels are self bleeding. So you just need to keep winding her over until she builds up the fuel pressure and will eventually fire up. Need a strong battery.

Is the fuel filter handy in those 525d's. If so fill the filter with diesel by hand and wind her over with the inlet pipe to the filter dissconnected. Wind her over until diesel starts to come out the pipe and then connect it back onto the filter.

Should save alot of winding as you're not forcing all the trapped air through the engine.
 

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Your car is self bleeding. Turn on ignition key and do not crank engine. While pump in tank is running (it will time out and stop after about 30 seconds) have a look at the bit of clear plastic pipe between the fuel filter and the high pressure pump. Can you see air bubbles? If this clear pipe is filled with fuel and there is no evidence of air bubbles no matter how small wait for tank pump and under passenger footwell pump to time out. Continue to view this plastic pipe for about another 20 seconds and both view and listen for air bubbles and fuel flowing in this pipe and associated pipes. If you hear or see air creeping from the high pressure pump and travelling back towards the filter you have not fully bled the low pressure supply line yet. Now simply turn off your ignition key and turn it back on straight away again. this will repeat the process. When it again times out wait and look for air in the plastic pipe. By now there should be none. If there is you might have a leaking injector leak off pipe that is allowing air in and causing fuel to run down the wrong way back to the tank via the high pressure fuel pump and back to the fuel filter and back to the tank. Assuming there is no air the car is nearly ready to try swinging the starter motor. Turn on the ignition key once more and the fuel pumps cut back in, wait for about 15 seconds and now turn the ignition key a little further to engage the starter motor for the first time. It should start an hopefully it will. This procedure works with all common rail fuel injected diesel engines that have electric fuel charge pumps.
 

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Discussion Starter · #7 ·
Your car is self bleeding. Turn on ignition key and do not crank engine. While pump in tank is running (it will time out and stop after about 30 seconds) have a look at the bit of clear plastic pipe between the fuel filter and the high pressure pump. Can you see air bubbles? If this clear pipe is filled with fuel and there is no evidence of air bubbles no matter how small wait for tank pump and under passenger footwell pump to time out. Continue to view this plastic pipe for about another 20 seconds and both view and listen for air bubbles and fuel flowing in this pipe and associated pipes. If you hear or see air creeping from the high pressure pump and travelling back towards the filter you have not fully bled the low pressure supply line yet. Now simply turn off your ignition key and turn it back on straight away again. this will repeat the process. When it again times out wait and look for air in the plastic pipe. By now there should be none. If there is you might have a leaking injector leak off pipe that is allowing air in and causing fuel to run down the wrong way back to the tank via the high pressure fuel pump and back to the fuel filter and back to the tank. Assuming there is no air the car is nearly ready to try swinging the starter motor. Turn on the ignition key once more and the fuel pumps cut back in, wait for about 15 seconds and now turn the ignition key a little further to engage the starter motor for the first time. It should start an hopefully it will. This procedure works with all common rail fuel injected diesel engines that have electric fuel charge pumps.
Thanks Mike

I have done all the above and no joy

One thing thats strange is the glowplug light is no switching off

I think i will check the second pump tomorrow
 

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you have a fault so, check pre supply pressure. first thing is check fault codes. if your having issues ask stephen maher for timo's number and i'll talk you through it.
 

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Discussion Starter · #9 ·
Got it sorted today

It was a slightly burnt relay for the second pump under the car that seems to be the problem so fitted a new one

Plugged it in to autoboss cleared all faults and its going perfect

Thanks all for the advice
 
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