2003 SL55 owned 3+ years, no issues, well maintained, but no new/recent maintenance performed - 60K miles on odo.. A few weeks ago we had driven about 30 miles from home, car was running great. Suddenly at about 60 mph, on Interstate 95, the engine seemed to 'maybe sputter' once then died completely. With lots of luck, I was able to move through 2 lanes of traffic over to the shoulder. while decelerating quickly (shifted to N asap). No start on dozens of tries - no indication of even wanting to fire. Eventually got a AAA roll back tow and car is now in my garage, After a few weeks, the front sagged down.as far as it goes (rear is still up normal).

Short background - before this happened we had been away a lot and the car was not driven for about 6 weeks. Then, shortly after returning home, I had emergency surgery for a subdural hematoma in my skull. Restricted from driving for about 8 weeks. Thus, the car sat in the garage for around 3+ months with one or two 5-10 mile trips before that morning's drive.

Had to leave home again 2 days after we got it home for another month, and am now home and trying to diagnose the issue. Cranks rapidly (both batteries full charge) but no indication of any firing. The tank is half full of gas (had some in it with Sta-Bil added last winter and another few gallon added when I started driving - wanted to burn up the old fuel before completely filling.

Any suggestions? Is this a symptom of the crank position sensor failure? The car had never failed to start immediately and run properly in the time I've owned it (about 10K miles in 3+ years). I put an OBD II scanner on it, and 'no codes' are registered.

I'll be extremely thankful for any help in diagnosis. Unfortunately, I am still somewhat limited in what I can do by the neuro-surgeons restrictions following brain surgery.

Gary Knox

 

Sounds like a fuel issue. Could be a clogged filter or maybe even a bad relay or fuse. Doesn't sound like a CPS since it still doesn't start when it is cooled down. Check your relays and fuses first.

 

Did you get any codes ?, if you can get a fuel pressure gauge see if you have pressure,you should hear fuel pump run for about 2 seconds when you turn key to on position, if you can do that and you have fuel pressure I’d lean towards crank position sensor.

 

I would start with crank position sensor. It's relatively inexpensive and easy enough to DIY.

 

Fuel pressure sensor get that checked, I had similar issue with mine, would try cranking but wouldn't start. I did change the filter managed to get it fired for 2 seconds then cuts out

 

CPS most probably . Cheap part , not so easy to replace .

 

My sincere THANK YOU to all who posted a reply. I have a new CPS installed (bought from FCP Euro, a Bosch 'made in Germany' OEM). By the way, this model year of the SL55 has it on the driver's side of the engine (LHD car) - I'd found varying statements on exact location. The new one and the one removed both have the same resistance - 1.1 on my digital VOM set on the 200K ohms scale. Once installation was complete I attempted to start the car - would't fire nor start.
Considering my limitations, I decided it best to leave further diagnosis/work to the dealer. So off it went on a rollback flatbed for the ~6 mile trip. Front end of the car had sagged to the bottom, so it was delicate getting it loaded/unloaded - the AAA truck driver did a great job.

I will post here when I have the diagnosis from the dealer and the repair completed. Thanks again for all your input.

Gary-

 

Hey Gary

Had same exact problem as yours however mine didn't splutter on the high way was on a local road and it starting running rough pulled over and since didn't start.

Went through the whole vehicle but didn't manage to get it started. Dropped it off to main dealers and after a few days later and a hefty bill we managed to establish it was the fuel pressure sensor. Try changing the fuel filter that did manage to get mine to start but then would cut out once placing foot on accelerator.

regards

 

CH04DRY,

Thanks for the input. I too felt it was probably a fuel supply problem, but the car was not located in a place/way in which I could attack that. It had a half tank of gas, and didn't want a gasoline issue in the attached garage!

PS:10/24/17: Car was completed at the Dealer's yesterday. New fuel pump, new fuel filter, and combined with the new CPS, the car runs perfectly. Driving home I thought - WOW - since I haven't driven this car in 4 months, I'd forgotten what a great car it is, and how much fun it is to drive it on our curvy 'deer path' roads.

All is well - just had to take out a mortgage on the house to pay off the dealer!!!!!!.

Thanks again for all your help.

G--

 

Glad you got it sorted out. Was it the in-tank fuel pump or the external pump? Apparently the AMG cars use two.

 

Yep, thought it was fuel from the start. Those were not symptoms of any CPS issue I've ever had.

 

dRockSL66,

The pump that was replaced was the external one.

Gary