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The car cranks but will not start. I tried to scan the car using Carly, but I did not receive any CODES, CEL is not coming on.
I also tried to disconnect the battery and reconnected it and still nothing. any suggestions would be appreciated.
Check fuel pressure/fuel pump fuse.
Any ignition related sensor would throw an error. Also it might be ECU/EZS/Immobilizer related issue.
I’ll check the fuel pump fuse next, what I did check was the starter fuse (fuse 52) I used a fuse tester and the fuse tester light didn’t come on, I tried changing the fuse but the same thing. Fuse tester light didn’t come on, and car still didn’t start.
I tried listening for the fuel pump, I got in the back seat and turned the key but I didn't hear anything. should I try bypassing the relay, before trying to replace the fuel pump.
One thing I forgot to mention is earlier in the day I started the car and I felt the car vibrating. I turned it off, and a few hours later the car wouldn't start again. (crank, no start)
I didn’t get a chance to check the fuel pump relay but I did get a fault code today when I checked the car with the Carly app. (Still no cel) “position sensor 1 for the crankshaft has a malfunction” didn’t know exactly what it meant but I figured I’d try and change the crankshaft sensor, I had a hard time taken the screw off, I’ll try again tomorrow (got too windy) but I did plug in the new one and tried starting the car and still no good. (Does it make a difference if the sensor is sitting in its place?)
Yeah, CPS is a common issue, the car won't start if it's not mounted correctly, CPS reads flexplate teeth which allows ECU to determine where the crankshaft in each point of time.
I didn't see it mentioned but you should ensure that you have more than a half tank of fuel. If the transfer pump is defective you could not have fuel available for the fuel pump. It could of course be the CPS but you can easily rule out the fuel tank if there is more than 1/2 tank of fuel.
Thanks for the reply, the car has 3/4 of a tank of gas. CPS will be the first thing I change, if that doesn’t work, I’ll look into the fuel pump.
Does anyone know if the starter fuse should have lit the fuse tester light when I checked it? Cause it didn’t and even when I changed it, the fuse tester didn’t light up.
I changed the Crankshaft position sensor, and that did not work.
I did spray some starting fluid into the intake and the car started up for about 2 seconds (was shaking) and as soon as I touched the gas pedal it turned off.
It definitely seems like the issue has to do with the fuel pump before I go changing it is there anything else I can do to make sure that it is the pump? Pump is pretty expensive and I don't want to just throw parts at it without knowing for sure.
There are couple of options how to test the pump:
1. Safe option: get access to the pump and check resistance between + and - on the pump, i think it should be around 1-3ohm (I'd say 0 is definitely a problem and higher them 100ohm as well).
2. Less safe option: remove the pump and connect it to 12v and see whether it works. Be careful even small spark might ignite the fuel fumes.
My fuel pump went bad and a helpful AAA guy told me how he knew. When turning it over get some to knock with there palm pretty hard beneath where the fuel pump is (in the middle of the passenger side rear seat. I think this just pushes a little gas through enough to start anyway. The next day I bought a California made pump of amazon for $30 as I was super broke at the time. It actually looks even better built than the original. No loss of power put 4k miles since (2 years ago) no loss of power or anything. The fuel pump itself is just a basic motor you can actually cut open the old one and just buy the motor for about $3 but that's a much bigger job. Changing it over was super easy maybe 2/10 difficulty but it is super dangerous if not done right. A followed a YouTube video took about an hour and that's only because I was being way over cautious.. Hope this helps.
I took the pump out (such a pain to remove the fuel hose, I had to just cut some of it)
I checked the ohms on the pump it was about 120 ohms. (did this while it was off and disconnected) did I do that right?
Also, I connected the pump directly to 12v and the motor did not move or make any sounds.
I'm thinking the pump is not good since nothing happened when I connected it directly to 12v. I'm ordering a new pump now and hopefully, that fixes the issue.
I just realized that the hose should have never been disconnected from the coupling. The coupling could have been unclipped from the pump.
I ended up breaking the clamp off and cutting some of the fuel hose to remove it.
I’m going to just reattach it and put a new clamp on. (Hopefully I didn’t cut it too short)
To make everything even more confusing I tried testing the pump again today, I connected it directly to 12v and I heard the motor running, yesterday when I did this, I didn’t hear the motor. Now I’m wondering if the pump is not the problem. The new one is arriving on Tuesday. I’m starting to think the pump is not the issue and it’s something else.
Tomorrow I’ll reconnect everything and see if I’m able to hear the pump running while it’s connected to the car.
I don’t think the filter was ever changed in this car. Especially since when I spoke to the dealer yesterday. I called parts department to find out if the filter was definitely in the tank, and they told me yes it’s in the tank but those filters don’t go bad. But when I told him I was changing my pump he suggested I change the filter also.
Yeah, those "mesh" filters inside the tank usually don't go bad only if you have some junk/debris in the tank. I can image it would be a problem with metal tank but not with our plastic ones
I'm having the same problem - crank but no start and no CEL.That should mean both CPSs are good, right? Fuel gage shows there's about a half tank and there's no pressure in the fuel rail. The mechanic says it's a fuel pump but he's not a Mercedes mechanic and he asked me to do some legwork and order the pump. Looking up part numbers for the fuel pumps and looking through various fuel system threads I've figured out that there's two tanks and two pumps under the back seat, one on either side. One is a transfer pump and one is the fuel pump for the engine. They both apparently have level sensors and they work together to keep the sides balanced, as far as I can tell, and both have to work or you essentially run out of gas with fuel still on the gage. If I'm wrong about any of this, let me know.
Still, I have questions -
1. How does this system work when filling the gas tank? If the pump on one side is supposed to transfer fuel to the other, how does the far tank get filled when the ignition is off? I'd guess there's an overflow of some kind but I've no good idea about how it really works.
2. How does the system return a fuel level? Do the sensors add to each other to provide a total to the fuel gage? Or does the car assume the tanks are equal and one sensor supplies a level to the gage based on only one tank?
One reason I ask is because I'm also having issues filling the tank. It doesn't want to accept fuel at a reasonable rate. It keeps backing up into the fill pipe like it's overflowing, burps kinda, and then lets me fill a little more. I'm hoping the issues are related but I don't really see it. But it's also not the problem I'm trying to solve.
When it warms up a little I plan to check fuses and the fuel pump relay in the trunk and then pull the back seats and check the voltages on the pumps. If that all checks good I'll pull the pumps on both sides and check the levels in each side. If only one of the pumps is working I'd expect that side to be empty and the non-working pump side to be mostly full. I could bench test after to confirm in case the fuel tank levels are inconclusive.
Again, if any of this is off base, please let me know.
this formu is a lifesaver! Thanks guys for your shares and tellings
i am completely new in the mercedes world, i have a clk200 1.8 kompressor from ‘07 and had similar issues with the car!
firs it stalled when driving, just a sec and then all ok! Till the 29th of December, in a parking lot on the mountain, crank and no start!
Posting this, maybe someone has the same issue!
Situation that i had:
-Morning stat, started and then stalled, restarted and all ok
-stalling while driving, for just a second then all ok!( did that for 3 times) i was already wondering about the CPS
- parked and never started!( tried everything, moving the shifter, moving the steering-wheel, pressing the brake, everything!
I had replaced the CPS,around 4 hours of work! Took down the airbox, intake and the hose that connects the airbox and the compressor( the one in the back) and that made alot of space! Managed to do it with a 6” extension and a 1/4 E8 socket and a ratchet( i was ready to use all the extensions that i had, but the 6” length one did the job)
After replacing the CPS, still no starting; went for the no4 fuse in the trunk, then tested the relay for the fuel pump( by the way in my car it clicks only one time( first out of 8 turns of key in the second position) all was ok there and the only one left was the fuel pump and i was so down, (new year, half of the holiday ruined, 2 towing truks,) and with a shortage in the budget! I have lifted the back seats, removed the dust panels and when i turned the key, i have knocked gently( not to gently 😁in the cover of the pump and it started! Now everything is ok and working; my guess is that a new pump should be on the wishlist,and i think you guys have the same opinion!
If you changed the CPS, and still not starting, help the fuel pump! 😁
So, if anyone is in the situation and is reading this, remove the backseat, knock firmly ontop of the cover to help the fuel pump run! Before going to the service and spend tons of money!
03-29-2021, 03:03 PM
in the cover of the pump and it started! Now everything is ok and working; my guess is that a new pump should be on the wishlist,and i think you guys have the same opinion!
