Ok guys, after a frustrating night of being stuck at the gas pump I could use your expertise. I've owned this thing for 3 years and have never had one problem until now.

Got gas, tried to start, started, immediately sputtered and died. Did this 3 times, and then did nothing. No click when I turned the key, nothing. Disconnected the battery, same thing. Start, immediately die, after 3 tries it once again does nothing.

I was convinced it was the crankshaft position sensor, but then someone says if it starts and dies it's NOT the crankshaft position sensor. So I'm at a loss, frustrated, and the car is still sitting a few blocks from my house in the gas station parking lot.

Any help would exponentially unequivocally appreciated. PLEASE OBI WAN! YOUR MY ONLY HOPE!!

 

Might be fuel pump relay related. Two ways to check.


1. Spray something flammable into the air intake and see if it runs as long as you are spraying. If it continues to run while spraying it could be your fuel pump relay in the RCM.


2. Open RCM and close the contact on the fuel pump relay and see if it runs after starting. If it does the coil is bad in the relay. To determine which relay is the fuel pump, looking at the opened RCM there are 5 relays, two on one side, three on the other. On the side with three the fuel pump relay is in the middle. You can jam something to close the relay or just have someone hold it closed.


LMK

 

I don't think its the fuel pump because I hear it turn on when the key is turned on, and I don't think it would do nothing on the 4th try each time. I think it's something with the keyfob. It came apart and batteries fell out right before this started happening.

 

Came apart.. as in totally and you could see the electrical board.. If so sounds like the RFID chip fell out... find it or tow home and order new key from Needswings..




Will add.. black and about the size of a grain of rice.. is shown in the thread on "how to replace key fob.."

 

A bit bigger than that, I'd say about the size of the first diamond I gave my wife.
Well, maybe the second one ......

If you find it, tape it on the ring surrounding the key slot till you can repair / replace the key fob.

 

I'm a native Texan.. my bad on the reference for you Alabama boys.. LOL

 

Just some thoughts:
1) The computer has a "three strikes and you are out" logic & must be reset before you can try again. That is built in.
2) Not sure about the XF but most cars have an ignition circuit that functions only when the starter is engaged to give a boost to the spark. If the run time circuit is bad, it will sputter then die as soon as the starter is released. This is an ignition issue.


The way to tell is to put a fuel pressure gauge on the fuel rail, should reach 30-40 psi while cranking and anything over 20 should idle.


If you have pressure and it dies you are back to ignition which also controls injector cycling.


Think I have seen mention of the SKREEM acting this way. Might do a search onnit.

 

You might try 54 PSI.. just ran fuel rail pressure check on mine.. and that is spec.


And as a note to that.. the missing RFID chip gives "skreem problem" symptoms.. anti theft has kicked in.

 

It this case, skreem module problems will exist. You guys have it right with the key fob being it. He stated he broke it just before it happened. This is one electronic I could live without....lol

 

So this happened around 10pm. I left the car at the gas station. After being up all night and searching what may be the cause, a friend of mine said I know Mercedes has some sort of chip in the key, maybe that's the problem?

I've had the keyfob apart several times (changing batteries, switching cases, etc) and don't remember seeing a chip. But never the less, I figured I'd go take a look. So around 5am (after not sleeping, worrying about how im going to get the car home without paying to tow it a couple blocks) I went up to the pump, looked around on the ground for a few minutes... And HOLY ****, there it was! I put it back in the keyfob and she fired right up.

Lesson learned!!

Cannot believe it was still there, in one piece, and I found it...a grain of rice.

 

Glad you decided to follow some sage advice! That was Texas sized rice.. correct?


Wonder if Valk can change my handle.. OBI WAN sounds kinda catchy.. LOL

 

I have posted another Texas sized Gold Star in your 'save' column.

 

This is the FIRST time the "cranks three times and nothign" complaint was so easily resolved. USUALLY, it's because the SKREEM is messed up and can't read the transponder in the key - and THAT means getting a new one.


THIS time, it could not read the transponder, cause the transponder was laying on the ground!

 

So mine is doing the same thing and I just replaced the module in the trunk that activated the air pump for the door locks when you hit the remote .... does this need to be reprogrammed?