SadW209Cabrio

I bought a used 2008 CLK 350 about 3 weeks ago with 90k miles from an independent dealership. Despite being equipped with Keyless-Go and push start, these features did not work and I could only turn on the car by turning key fob in ignition. I was not provided a second key (although I planned to get 1 soon that could be programmed as necessary). I was changing out the rear license plate and my dumbass accidentally let go of the trunk lid, with my 1 key in the trunk and all doors and trunk were locked. I then had to call roadside assistance who came by and opened the car driver side and after that popped the hood, disconnected and reconnected the battery a few times while pressing the trunk release button by driver side to open the trunk. I was able to get my key..happy ending right? WRONG!!!

I can open and close the car with key fob but am not able to start the car, the key turns in the ignition, revs up but engine does not start. All electronics and lights work fine. Even tried jumping the battery (know it is advised against but was desperate but no luck).

I have browsed related threads and am desperate to hear of any other ideas ahead of what may be very costly repair work coming up.

• Battery is good, even under a load (took it out and tested at local parts shop)
• Checked all fuses, they are all good
• Starter relay seems to be good
• Car has fuel
• I do smell fuel after trying to start, no visible leaks so I am thinking fuel pump and injection stuff is probably fine since it was driving fine literally hours before the incident.

I feel like the car had some kinda issues before which is why the keyless go and push start did not work...almost like someone "hacked" the ecu to get it to work with maybe another mercedes key and when the anti theft alarm when on and battery got disconnected...something got jacked up...or I am overthinking this.

I am thinking this is an EIS, ECU, issue.and maybe a key programming issue, something between these systems became out of sync, is there anything else I can try to DIY self diagnose?

Was pretty excited to be joining the world of mercedes owners...but didn't expect to be dealing with these kind of issues so soon.

dzmitry

EIS wouldn't allow you to to turn unauthorized key, ECU wouldn't crank the engine with unauthorized key. Both EIS and ECU know key ids, that's now DAS 3 works. I don't think that Mercedes changed this behavior from m2.8 to me9.7
There are two most common causes of "engine cranking but not starting" problem:
1. Fuel pump (fuse or the pump itself)
2. Crank Position Sensor

When you turning on ignition can you hear fuel pump priming? Can you check fuel pressure?

SadW209Cabrio

Appreciate the tips. I tried to do a fuel pump hearing test...had my wife put the key in ignition and turn to just before having the car start...I stood outside by the fuel cap area and didn't hear anything. Is that the right way to do the hearing test for fuel pump? If so, seems like fuel pump isn't doing what it's supposed to. What is extremely odd is that this only happened after the battery reconnecting situation...making me feel like there's something electrical going on....what are the chances my fuel pump happened to crap out at the same time of all this stuff?

dfrois

Usually, when a petrol engine spins on the starter, smells of petrol, but doesn't start, it's lack of spark...you may have flooded the sparkplugs. If you don't have a code reader, you could try removing and cleaning, or replacing, the sparkplugs. Sometimes, after a few hours, the petrol on the plugs evaporates enough to allow to start the engine.

That said, I would think a bad fuel pump would throw up codes, and light up the Engine Management light on the dash. But, I never had a CLK 350 petrol...

Are you sure the fuses are fine?

SadW209Cabrio

Have not checked spark plugs but as I've read around forums some more, I am suspecting something in the prefuse next to battery may have blown when battery was reconnected. Wish I checked that as well...but I've already towed it to an auto electrical shop, hope to find out what happened soon.

SadW209Cabrio

Update...mechanic stated that the cat turned on yesterday but wasn't able to get it working today. Theory, tow truck pulling the car at an angle got some fuel into the engine, which allowed it to crank.

Mechanic says it's the fuel pump that isn't working. I watched him check the fuel pressure and there us none (so my hearing test was correct). Is there a fuel pump kill switch that could have been set off when the alarm went off and we disconnected battery?

The shop plugged in the ecu and there are no errors. I gave the green light to try and change the fuel pump...I have a hard time believing the pump just died but maybe it was in poor shape and just happened to crap out. The fuse and relay are good and shop confirmed it. I feel like there's got to be something else electrical we're missing. He doesn't believe it's a prefuse issue.

dzmitry

You are not the first one :-D
Check this thread I posted couple of suggestions to test a fuel pump there https://mbworld.org/forums/clk-class...-no-start.html

dfrois

These cars have, I believe, a fuel cut-off switch that is suppose to disconnect in the event of a crash or heavy bump, but I never heard of it switching off with battery manipulation.

If it has is, it should be in the Owner's Manual.

The fuel pump is accessible through a cover underneath the rear seats. Maybe not too hard to check?

SadW209Cabrio

Dzmitry, u were spot on! Car started after fuel pump change. Unfortunately I got a check engine light turn on after driving the car a couple times....now got to deal with that. Any ideas? Improper install? Ecu issues? I'm starting to get the feeling that I bought a used car with known issues

SadW209Cabrio

Happy ending to this story. After driving around a few times, check engine light came off. Guess it took some time for the car to calibrate the new fuel pump. Thanks everyone.