Ran out of gas - throwing misfire code in #4
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Joined: Jun 2021
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From: Utah
GL450
Ran out of gas - throwing misfire code in #4
I Just replaced a failing fuel pump. 2 months later the car ran out of gas. I filled back up and noticed code misfire #4 I still hear my new pump priming and it has pressure when I check the fuel rail valve.... Where do I start? Replace fuel pump in case its was damaged to running on no fuel? Check the injector? Is there a way to bleed or re-pressurize the line in case is sucked air?
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Joined: Jan 2023
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2003 E320
First step is to clear the codes. Likely that misfire happened from the lack of fuel and is no longer present. Do you hear a misfire?
Fuel pump shouldn't be damaged from running dry for a few seconds. Don't know about these cars specifically but a general bleeding method is to disable ignition module, crack each injector line individually, crank engine until you don't see bubbles, repeat for each injector - or just drive the car until all the air is out.
Fuel pump shouldn't be damaged from running dry for a few seconds. Don't know about these cars specifically but a general bleeding method is to disable ignition module, crack each injector line individually, crank engine until you don't see bubbles, repeat for each injector - or just drive the car until all the air is out.
Thread Starter
Newbie
Joined: Jun 2021
Posts: 11
Likes: 0
From: Utah
GL450
First of all I appreciate you taking the time to answer me.
I have looked all over to get answers to an avail. I live in Utah and its been below 25 degrees here....everything is frozen..all lines and did start disassembling to get to the injectors.
I will follow your advise ... My thoughts were to get to #4 injector and pull it to see if it is clogged. When I am down to all injectors I will give your suggestion a try.
@winter111 If I run into another question, I may reach out again. Thank you!!
Yes I do hear a misfire, The fuel rail seems to have plenty of pressure. I agree with you, don't think it's the fuel pump.I do hear a misfire...really rough idle. I am unable to clear the code with my scanner..not sure why.
I have looked all over to get answers to an avail. I live in Utah and its been below 25 degrees here....everything is frozen..all lines and did start disassembling to get to the injectors.
I will follow your advise ... My thoughts were to get to #4 injector and pull it to see if it is clogged. When I am down to all injectors I will give your suggestion a try.
@winter111 If I run into another question, I may reach out again. Thank you!!
Yes I do hear a misfire, The fuel rail seems to have plenty of pressure. I agree with you, don't think it's the fuel pump.I do hear a misfire...really rough idle. I am unable to clear the code with my scanner..not sure why.
Last edited by Tommyworx1; Jan 21, 2023 at 11:59 AM.
Newbie
Joined: Jan 2023
Posts: 13
Likes: 0
2003 E320
First of all I appreciate you taking the time to answer me.
I have looked all over to get answers to an avail. I live in Utah and its been below 25 degrees here....everything is frozen..all lines and did start disassembling to get to the injectors.
I will follow your advise ... My thoughts were to get to #4 injector and pull it to see if it is clogged. When I am down to all injectors I will give your suggestion a try.
@winter111 If I run into another question, I may reach out again. Thank you!!
Yes I do hear a misfire, The fuel rail seems to have plenty of pressure. I agree with you, don't think it's the fuel pump.I do hear a misfire...really rough idle. I am unable to clear the code with my scanner..not sure why.
I have looked all over to get answers to an avail. I live in Utah and its been below 25 degrees here....everything is frozen..all lines and did start disassembling to get to the injectors.
I will follow your advise ... My thoughts were to get to #4 injector and pull it to see if it is clogged. When I am down to all injectors I will give your suggestion a try.
@winter111 If I run into another question, I may reach out again. Thank you!!
Yes I do hear a misfire, The fuel rail seems to have plenty of pressure. I agree with you, don't think it's the fuel pump.I do hear a misfire...really rough idle. I am unable to clear the code with my scanner..not sure why.
Some emissions related codes on modern cars are unable to be manually cleared and must be cleared by the car itself after it has determined the issue is fixed, this is to prevent cheating on emissions testing.
If you have an auto parts chain store nearby, you should be able to rent a fuel pressure tester for free, to verify.
Again, just as general advice and not Mercedes specific (some higher end cars require injector adaptation coding), since you do actually notice a misfire I would take the injector from the misfiring cylinder and swap it with another. If the misfire follows, the injector is bad, if the misfire stays, it's something else (spark, fuel, air, timing, compression).
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