Hi all and thanks in advance for your input.
Car: '07 E350 with about 84k on the odometer.
Situation: Car started and initially ran fine. A quarter mile up the road, it starts bucking and dies. Towed it back to my driveway to troubleshoot.

Initial codes were misfire codes along with P0336 - Crankshadft Position Sensor.
Replaced CPS, but car will not start. It will crank and start briefly, only to die a couple seconds later.

Unplugged the MAF: Engine starts and will run for a bit longer, but still dies quickly (a few seconds) - so the MAF seems to be good.

Checked fuel pressure at the rail: 55 PSI while cranking etc., so it's fine.

If I clear the codes, P0336 will show again, but it takes a few start/die cycles for it to show again.

I'm going to get another new CPS in the hope that the one I purchased is bad (aftermarket CPS - will buy new one from dealer).

I don't know how old the battery is. It looks fine on a meter, but I haven't had it load tested. If I connect jumper cables to another car, the symptoms persist - car still won't start.

Questions:
Is it possible that a marginal battery could cause these symptoms (even if I jump it to another car)?
Could any blown fuses cause this (if so, which ones)?
Is there anything else that could cause this situation?

Thanks!

 

Battery reads ~12.5V on the meter, but if the new CPS doesn't correct the problem (assuming no damaged wires - need to check that), I'll get it load tested.

Thanks for the input!

 

Update: Installed new CPS and checked wiring. Unfortunately, it still won't start. However, I'm not getting any codes. So, I connected the fuel pressure gauge to the rail again. Interestingly enough, there's no pressure turning the car on (not starting the engine). When I start the engine, the pressure jumps to about 50 PSI and the needle wiggles rapidly. I'm thinking I may have a dead fuel pump since the pump should engergize when you turn the car on and you should be able to hear it as well (and I'm not hearing anything).

I hate the thought of purchasing a new pump without being absolutely certain, but I'm out of things to test.

Any other thoughts/options would be most appreciated.

Thanks!

 

Still trying to figure this out. Can someone confirm that the fuel pump should energize when turning the ignition on (but not starting the engine)? I'm puzzled that I get no fuel pressure with the ignition on, but it jumps to around 55 PSI when cranking the engine. BTW, I don't hear any fuel pump noise.

Battery wise: Placing a meter on the battery shows 12.6V. When starting the engine, it starts to climb and gets to about 13V before the engine dies (just a matter of a few seconds at best).

So, to summarize the symptoms at this point: Engine starts and will run at about 1k RPM briefly (a couple or few seconds) and dies. No codes.

 

I spoke with a local mechanic and he confirmed the fuel pump should energize briefly when switching the ignition on (but not starting the engine). I've got a few more test to do, but it's looking more and more like a failing fuel pump.

 

Well, I've found the root cause: Bad gasoline. I don't know if the bad gas came from the gas station at the last fill up (the day before this all started), or if the car was sabotaged. Regardless, the gas is a cloudy, dark amber color. I don't know yet if it killed the pump, but it's, at the least, clogged the filter. So, since I have no way of draining the tank and disposing of the bad gas, I'll have it towed to a mechanic that can deal with it - ka-ching$$$!

Thanks much for the help/input on this.

Here's a pic of the gas (glass on the left is normal gas and the glass on the right is out of the Merc):

 

definitely keep us posted. Where did you get your gas the day before?

 

Wal-Mart. Not where I usually get gas. However, this is my wife's car and she insists on getting gas there because it's cheaper. If that's where the bad gas came from, this will be the single most expensive tank of gas we've ever purchased ;-)

 

I would pursue the station of the last fill up and if no resolution there, I'd file an insurance claim.

 

The gas station has denied receving any other reports of bad gas (surprise, surprise). Since I have no way to prove the bad gas came from them as oposed to someone pouring some nasty junk into the tank, there's no piont in wasting my time chasing them to pay my repair bill. So, I've filed an insurance claim. The car is currently at a local Merc dealer and I'm waiting to get their diagnosis.

I suspect they will confirm bad gas and need to drain/clean the tank, replace the sending/filter unit, flush the remaining bad gas out of the fuel lines and clean the injectors.

I'll report back when this has all bottomed out. Way too much fun :-(

 

Update (and likely my last post on this topic): The Mercedes dealer has confirmed the gas is bad. They are recommending replacing the fuel pump as well as the other parts I listed in my previous post. All that remains is working out the cost details between the dealer and the insurance company.

So, in summary, the P0336 code turned out to be a red herring. Moral of the story: If your car dies not too long after you fill the gas tank, pull a sample from the tank before your worry about the codes. If I had done this, I would have saved myself a few days of scratching my head. However, in my defense, there are far more instances of failed crankshaft position sensors than bad gas. C'est la vie. Turn the lights up and roll the credits - show's over ;-)