Help Please E320 CDI Cranks But Won't Start
So, right now I am stumped since it hasn't given me any codes. I charged the battery and have verified that the low pressure pump is getting fuel to the filter. Right now I am thinking it could be a clogged filter, or possibly bad fuel. Without and trouble codes, I am having a really hard time pinpointing what it is. Does anyone have any ideas of other things I could check. If I can, I will change the fuel filter tomorrow. I tried today but it was 29F outside and I couldn't get the hoses off of the filter.
The thing that puzzles me is if it was a high pressure fuel pump issue, I would expect it to be a much slower transition from starting fine to hard starting to finally not starting. This went from no issues to not starting in the space of about 100 miles. It is really starting to seem like bad fuel or a clogged fuel filter (that only has 10k miles on it). Like I said, if I can get the hoses off, I have a new fuel filter ready to try. This will also give me a chance to see what the fuel looks like and see how flow is out of the filter. But, as you are alluding to, everything is a guess without some data.
One more question, do these lift pumps have a history of slowly getting weaker, or do they fail all at once? One thought I had is if the low pressure pump is just not putting out enough pressure, it may be the cause for the hard starting, but if it can get started, the high pressure pump should be capable of pulling enough fuel through the system since it is positive displacement. I would just replace the low pressure pump, but I don't really want to take a $500 gamble on that.
Try old cam or crank sensor, if there is some compatibility problem...?
I remember hearing some issues with primer pump wirings, but it also was deteriorating over time, not sudden. And then there has been couple of cases where sender unit in tank has been glogged badly.
Dont know anything about code readers, using Star of my own...
Like you mentioned earlier, I think I really need to know rail pressure when I am cranking, and also I need to check the filter. Those two things should help narrow it down.
I also hooked up my Scangauge II to it and noticed the battery voltage was below 12V with the key on. I have a charger on the battery now and will try again with it fully charged, but I am wondering if a weak battery could cause these issues.
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Unfortunately most of old, easy remedies don't work with digital rail injection.
I wold try some ether (starting fluid for diesels) to confirm fuel problem, but be very careful with dose.
Good luck.
Thankfully I figured it all out. The initial problem was the cam position sensor, which was only causing a problem when it was hot. It was after I replaced the crank position sensor that it wouldn't start at all. So I put both old sensors back in and it still wouldn't start. I then went to put the new crank position sensor in and noticed that a small piece of plastic that had broken off of the engine cover before I even owned the car had fallen into the cutout in the block for the crank position sensor when I installed the new one, and I hadn't noticed. I removed it and put the new sensor in and it fired right up, but gave me a cam position sensor code. So I replaced the cam sensor and no more codes and it starts when hot. So, it was essentially my error the whole time, but thankfully I figured it out.
My question is : If the fuel filter is cloged does the pump work




My question is : If the fuel filter is cloged does the pump work




Another thing i would add is that since i have changed the ecu I heard the fuel pump making less noise then with the original old ecu.
Does this mean that i may have low presure ? If so what causes it




-the prime pump at the tank who gives few psi pressure
-the injection pump that gives about 4000 psi at idle and tens of thousands psi when running.
You can test prime pump by opening filter bleeder and cycling the ignition.
Be ready for diesel squirt.


