# Crank (No Start) after diesel injector replacement



## TonyInUSA (May 4, 2016)

I just now replaced a faulty fuel injector in my 2010 335d. It had thrown a CEL and there was a discernible miss at low RPMs w/ medium load (driving uphill into the garage). The mechanical part was pretty uneventful, had the new injector installed in about 45 minutes. Now that the engine was back together I tried to start it. It would crank, but I limited it to just a few seconds (less than 15) for fear of running the HPFP without bleeding out the system. I got nothing. As means of comparison, after replacing the FF before, the car would only need maybe 3 seconds to re-fire back up. Curious, I had a friend crank the car as I cracked the HPFL to the replaced injector, no fuel. So I went to the local BMW dealer to ask if they use diagnostic software to activate the fuel lift pump to the HPFP. They said no, just simply crank the motor till it starts. I asked how long to crank. The rep said sometimes 2 minutes! I said weren't they concerned about the HPFP cranking that long w/ no start. He simply said no. So I am wanting to get the car started, but at the same time do not want to damage anything. Does anyone have any experience on re-starting the motor after an injector replacement or after opening the HPFL for any other reason? Much appreciated.
Tony


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## Doug Huffman (Apr 25, 2015)

I thought, in my ignorance, that there is more to replacing a fuel injector than the mechanical issues.


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## TonyInUSA (May 4, 2016)

True Doug, it sometimes can involve other procedures, but often than not cracking open a line downstream from HPFP would not prevent starting. Case for example, on all of my Cat 3306 & JD 466 engines, swapping out a bad injector is very simple. Just change injector and then re-start engine. It may take a few seconds for fuel to purge any air completely through injector, but would not prevent re-starting. My main issue is Dealer's viewpoint that 2 minutes cranking to re-start the car seems irrational and downright stupid.


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## oceandiver86 (Jan 25, 2015)

yes there is a bleed process in ISTA-D after you opened the high-pressure system.
otherwise just cycle the ignition a couple of times. the low pressure pump should then run for a couple of seconds.

also did you realign your new injector to the DDE? there is a code on the injector which has to be written to the control unit


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## TonyInUSA (May 4, 2016)

OceanDiver86 ~ Thanks for that, no I didn't know about the registering process. What value from the new injector needs to be imputed into the car? I've got the BT enthusiast tool coming in tomorrow, will that allow me to change the values?


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## Doug Huffman (Apr 25, 2015)

From page 61 BMW Advanced Diesel Technology: "Piezo-fuel injectors not only bear the hydraulic tolerances but also information concerning the stroke characteristics of the injector. This is a separate classification for the injector voltage calibration.
This information is necessary due to the individual voltage require- ment of each fuel injector. The fuel injector is assigned to a voltage requirement class. This replaces the seventh digit of the numerical combination on the injector for hydraulic adjustment.
A piezo-fuel injector therefore has only six characters for the hydraulic adjustment (due to a more precise manufacture of the piezo-fuel injectors) and a seventh character for the injector voltage adjustment."


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## TonyInUSA (May 4, 2016)

Doug ~ That was excellent! I didn't know about this. So am I to understand that if both the original and replacement injector have the same electrical values, the control unit doesn't need to be updated (registered)?


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## oceandiver86 (Jan 25, 2015)

this is a readout from ISTA.

Compare the numbers from both Injectors.

I don't know the tool you are using. just search for something like "Injector calibration" or "Injector adaptions"


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## BB_cuda (Nov 8, 2011)

I wouldn't listen to the dealer's advice concerning extended cranking. Power the lift pump and bleed out the air. My crude method worked but your mileage may vary. With battery disconnected, I pulled back seat out. I removed the ~ 10" diameter plate which accesses lift pumps lead. Disconnect harness. but note polarity beforehand. The striped lead is the + pin. Directly power the pump. I used a 12V battery from my older Honda accord. I've heard some use an ATV battery. I did this and heard noises and flow coming back into the tank including hissing from air bubbles coming back into tank. 

I'm no authority on the injector change. A friend works on Dodge Ecodiesels (Dealer Tech) and he has to scan in the new injector serial number after installing. I will ask him how they prime the system (or if they even bother... hope so).


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## TonyInUSA (May 4, 2016)

Thanks again for all the help. I've learned quite a bit already. My main concern is damaging anything, preventing any damage is much easier than repairing it (costs less too). I'll have more time tomorrow to get to priming the pump. Let's see what happens.


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