Car cranks a bit before it starts
 

When my wife was leaving today, I noticed the engine cranking a bit without starting. It started fine the second try. My wife said it did this yesterday as well. This never happened before. It's a 2008 E350 with around 53k miles.

Any ideas?

Was it hot start, or cold start?
I would start with hooking up fuel pressure gauge.

Hot start both times. Let's say the fuel pressure is low, does that mean the fuel pump has to be replaced?

Go to a dealer. Get you some new fuel system components.... aka complain about a fuel odor. in return you'll get new pump and pressure regulator.

as for long crank, inspect starting and charging system as well. Battery could be weak and or starter may be starting to fail.

A amp clamp around the starter wire would tell you how many amps it's drawing just to start. If it's excessive may be a good idea to replace starter.

No residual fuel pressure on hot engine means leaky injector.
Leaky injector floods the engine.
All you need is $19 gauge to narrow the troubleshooting.

What's the voltage of the battery? Is it OEM? You can go to an auto parts store and they will usually load test it for free. You can also get the voltage on the display. Put the key in the ignition, turn it to run, but don't start the car, hit the reset button 3 times when it's displaying the temperature and it will give you the voltage.

I have this same problem and with a new battery. Alternator tested fine as well. The car always starts but cranks, never stalls. Weird.

The Epilogue
 

Well, I didn't want my wife to get stranded, and the long cranking was happening every time -- hot or cold -- so I told her not to drive the car (she used my Jaguar instead). I made an appt with the MB dealer and took it there after the car sat idle in the garage for 4 days. Sure enough, when I started it to go to the dealer, it cranked long again, but rapidly. Dealer did a diagnostic test and found nothing wrong. Car stayed there for a day and a half and the mechanic said it started quickly every time. I picked it up and it's been starting normally and quickly ever since. I paid $155 + tax for a diagnostic testing. Maybe I should have just waited for it to go away on its own.

I want to run down the gas tank as much as possible and then fill again. I'm also going to buy some fuel injector cleaner additive just in case.

The service advisor said my 4-year old (Mercedes AGM) battery could be the culprit, but I highly doubt that given the rapid cranking and normal voltage after sitting overnight. I don't see any reason to waste nearly $200 for a new (non-MB) battery until it starts to crank slowly.

Thanks to everyone for their responses.

Same issue here. Haven't bought it to the dealer and won't. Sometimes it cranks quick and other times it's a long crank. The battery is 1 year old. Oh well.

Have you tried fuel injector cleaner in the gas tank?

Nope, didn't think of that. Should I and if so what brand should I buy? I assume there will be no ill side effects?

Techron is pretty much the same thing as what the oil companies add to their gasoline to make it "Top Tier"... you do always use a Top Tier fuel brand right?

https://cimg7.ibsrv.net/gimg/www.mbw...0717a0bd14.jpg

https://www.amazon.com/Chevron-65740...ncentrate+plus

Yes, I religiously put in 93 octane at the gas station (Gulf). Should I still use this stuff then or?

High octane doesn't make it a top tier retailer. "Top Tier" has to do with the additives (Detergents) added to the gasoline:

http://www.toptiergas.com/retailers/


If a retailer has gone to the trouble to be certified, you will usually see this sticker on their pumps:

https://cimg0.ibsrv.net/gimg/www.mbw...84b2392ca7.png



:zoom:

Interesting and never heard of this. I'll have to find the nearest one to me and see if it makes a difference. Thanks for the info.

No, don't use injector cleaner. You manual is pretty specific about not using that. If you are using Premium, no need for cleaner. It really does sound like a fuel pump/sending unit failure. Filter may be getting clogged (especially if you run the fuel low a lot). I replaced my filter and sending unit at the same time, but I had about 144k on both. Try just the sending unit as it has the filter built in. But first check pressure, it's easy and quick.

Since you haven't been using a top tier gasoline, you may want to add a specific injector cleaner:

https://cimg5.ibsrv.net/gimg/www.mbw...b580cb7e9d.jpg



https://www.amazon.com/Chevron-10055...R7RB6X5834435Y

...and always stick to the top tier retailers. After two or three tanks of a top tier gasoline, there's no point to using any additives.

Will check this out as well. Yes, I did hear that the manual said not to use additives. Maybe the issue is that for the past 6 months im only driving the car about 3 miles a day.

That very well may be. These cars don't really like short trips; ESPECIALLY in cold weather. Come winter, take some longer trips every few weeks.

Follow up
 

Well, the Techron did nothing to help with the long cranking problem. In fact, it got to where it cranks very long every single time, so we took the car back to the same dealer who couldn't find anything wrong three weeks ago.

Now they're saying they are certain it is the fuel senders (not fuel pump) that need replacing. I pointed out the 15 year warranty on fuel-related components (which includes the fuel senders), but they said that it doesn't apply because there is no evidence of a fuel leak or fuel smell (they have a fuel odor detector apparently). The language of the letter I got from MBUSA leaves some room for debate, but since I pushed the issue, the dealership said they'd pay for the parts (around $800) and I "only" have to pay for labor ($510). Their labor rate is $155/hr (a bit lower than what Porsche and Jaguar dealers in the area charge), so that comes to about 3.25 hours of labor.

Does anyone know if 3.25 hours is about right for changing 2 fuel senders?

Thanks.

The senders take only few minutes to replace and my friend bought new pump at dealer for $560.
I would hope the $800 part would be whole tank, but dealer can come with outrageous mark ups, so everything is possible.
In NY you should have several dealers in small radius.
Why don't you drive to another dealer and complain about gasoline odor after filling up? ;)

New update - car stalled last week and wouldn't start. Had to tow it to dealer. Turns out it was the starter and had to be replaced. $1150 bucks at the generous dealer...

Have you fixed your problem by any chance? I’m also having the same issue

This was quite a while ago and we traded that car to the dealer where we bought it from (for another E-class wagon). We took it to the MB dealer, and it was something like (I believe) $1300 but they charged us about half as a goodwill repair. The car spent several days there before it was all fixed.

This sounds 100% like low fuel pressure delivery - Use a scanner to confirm how pressure ramps up.

Forget about throwing parts at this without preliminary troubleshooting.