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Discussion Starter #1 (Edited)
The car had been cranking a few seconds before starting, for about a week before it stopped running. I discovered one of the cells in the battery was bad. Therefore, It was only putting out 10.5v. I installed a new battey, and still no help. All fuses look good. It cranks good. I suspect the crank position sensor, because I can hear the fuel pump, and I read that if the crank pos sensor goes bad it could cut off the ignition and fuel.

I hooked up an OBDII, no faults. Unless it is somthing to do with the security system, after I changed the battery? I would like to confirm the fault if possible before changing any parts. Any Ideas???
Thanks, Justin
 

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Normally when the Crank Sensor goes, you get a code. I am thinking more of an alarm system issue with the battery being removed.
 

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Discussion Starter #3 (Edited)
Hi, I read all the posts for batteries and several on the ignition immolbilizer. Plus, I read the description and operation in the maint maintenance manual. I didn't see anything that would cause this problem from a battery change. The only thing I read in the manual, not from any posts, that the car needs to be unlocked for atleast four minutes before the battery is replaced, or it could cause an anti-theft fault. I was'nt getting any any OBII faults though.

The manual said if there is fault in the unit to just clear it. It didn't explain how to clear it though. Unless it was talking about a DTC fault, although it didn't mention DTC. Therfore, I think it has a diffrerent proceedure for clearing faults. Plus, I think I had the doors unlocked for atleast found minutes before, I took the battery out.

Also, the unlock button function on the key works fine and the radio comes on. I plan on checking the anti-theft computer out. Although, I am not sure what to do with it, or if it is okay to unplug it, without reprogramming it, or what not.

I still think it may be a crank pos sensor. Although, I am going to check out the anti theft unit, if anyone knows a good reset for that, it would help. Then, also try starting the car in neutral to see if that helps. I was reading through the manual and it said the starter has to come out to get to the crank pos sensor. Then, the new sensor has to be adapted to the engine control unit via the mercedes STAR scan tool. I read about other DYI people replacing their own crank pos sensors and they never mentioned having to complete this step. Does anyone have any info on this?

I am also open to suggestions on what other possible causes it could be, or any troubleshooting proceedures. Thanks

Justin
 

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Discussion Starter #4 (Edited)
After figuring this out this car's anti-theft system is not installed or it is disabled because the fuse spot was blank, and where the crank sensor is. I tried getting the sensor off. Man, I need a long extenstion with an allen socket to get that tight sucker off. The manual says to take the starter out. That is an option although, I could'nt get a wrench or wratchet on the top bolt squarly. I ended up taking the bracket off the fuel air manifold and was able to reach my arm down there. the bolt was too tight for a regular allen key. I need the socket and extention and I think I can do it.

I decided to finally check the fuel rail for any fuel present. To my suprise, there was nothing. I checked like three or four times. I couln't believe it. Then, I turned the key to the ignition, and went back to the fuel pump adjacent to the tank and nothing, it was dead. I kind of mislead my self. There some sort of pump connected to the throddle assembly, and I heard what sounds like fuel cycling through it, back to the tank. That is why I originally though that fuel was being sent to the engine. Aparently, that pump I heard at the engine serves another purpose. Maybe it boost the pressure prior to the fuel going the injectors would be my guess. I will have to look it up in the manual. The sucker runs when the ignition is on though.

I am going to try to get a pump today, and see how that goes. I keep ya all posted.
 

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Discussion Starter #6 (Edited)
okay, i'm finally getting back to everyone, The external fuel pump adjacent to the tank was bad. i replaced it, put gas in the car and it runs. However, and this is partially why it has taken me so long to respond, the car dies like it has ran out of gas at only a half a tank. I believe the fuel gauge is accurate, and there is still fuel in the tank. I am thinking posibly one of the recirculation pumps in the tank is inop. i don't know yet. its my sisters car and i haven't been able to look at the car when is fails at half a tank. any suggestions would help. i plan on checking the fuel pump inlet line to see if it has fuel, i bet not. the tank is split, so i am thinking one half of the tanks is not getting used.
 
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