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Discussion Starter · #1 ·
I have a 2001 a170 cdi that ran out of fuel. I have since put more fuel in it, to almost half a tank. Being that it is a diesel, I went online to see if there was anything special for getting it primed and started. I found information that lead me to believe it would self-prime simply by turning the ignition (not cranking) for a matter of some seconds. Turning the ignition back off and repeating the process at least once more before attempt to start the car. I guess doing so initiates the sending unit (pump) to send fuel.

Anyways, I attempted this a few times. It never started. Then I decided to replace the filter, which needed to be replaced anyways. Again, I repeated the process of trying to self-prime. Still the vehicle will not start.

I have had issues with other cars in the past with similar problems. In my 80 mustang, you could hear the sending unit turn on with the ignition, but I hear no noises with my Mercede, which leads me to think the pump is not working.

Any ideas, assistance, or insight would be greatly appreciate.

Notes:

  • New battery
  • New filter
  • as far as I can tell, all electronics are working
  • I do not have a manual for the car.
  • the car work fine up until it ran out of fuel.
 

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...........................I found information that lead me to believe it would self-prime simply by turning the ignition (not cranking) for a matter of some seconds. .............................................
Aha! That IS the problem. Your detailed info helps! Engine will self prime only when cranking.

Diesels are equipped with two fuel lines, IN from the tank and RETURN back to the fuel tank. Cranking causes unused (unburned) fuel to return. It is this flow that eliminates air bubbles within the tank. A solid stream is essential; peculiarity of diesels. Air-in-fuel is tolerated to mild extent. Nothing in this universe is perfect. However, running out of fuel causes air sucked in your entire fuel system. b.t.w. Fuel filter R&R requires same procedure for system bleeding. But here one is dealing with much smaller air quantity - generally in fuel line portion in immediate vicinity of filter.

Assuming there are no leaks in fuel system, here are some tips:
1. Ensure battery is fully charged.
2. Ensure reasonably clean air filter. Diesels swallow copious air volume.
3. Do not engage starter for more than 30 secs at a time. Allow to cool down. Do not give up! 4 to 6 shots should get you going, provided assumption above is true.
 

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Discussion Starter · #3 · (Edited)
Thank you for the reply. I had not continued this course of action because I read that it can cause damage. Is there any clarification that damage can be done if I continue to attempt starting the car?
 

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........................ I read that it can cause damage. Is there any clarification that damage can be done if I continue to attempt starting the car?
Yes, starter will burn out if over-heated. To avoid damage follow point #3 in earlier reply. Your starter is fairly robust. After all, it is a Mercedes. Repeated attempts in short bursts are aimed at bleeding (technical term for eliminating air) your fuel system. MB designed the system that way so don't be afraid. Dealerships use same procedure!

Way back in 1970s diesels MB used a manually operated, built-in pump. It was dropped in favor of using the starter to accomplish same.
 
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