forfour.co.uk
Forum => General Smart Chat => Topic started by: Gareth79 on March 07, 2017, 09:59:06 AM
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Just posting while I'm waiting for the recovery truck really. My ForFour lost power in the outside lane of the M25, I managed to get it to the hard shoulder. It turns over but won't start, in fact no sign of if even catching. I don't recall there were any warning lights beforehand and no noises. It has all fluids, Inc petrol which was my first suspicion (i put in half a petrol can of fuel just in case)
I'm away for a week (missed my flight!), any ideas for what to look at or point a mechanic at when I get back? Quick search reveals clutch actuator might cause this?
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Fuel pump failure is possibly my first thought given the description though I have never heard of failure of that type on the ForFour before. As I understand it, your car is a manual so it won't have a clutch actuator.
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Yes I was just reading more and it's a part on autos. Fuel pump or something in the ignition was my next thought too.
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I guess it does spin over with the starter motor... If that is the case, then for ignition, you need air, a spark and fuel. The air intake is unlikely to be blocked up given where it is which leaves fuel and a spark, which means either the fuel pump or perhaps the fuse to the ignition coils (#34- 10A), the pump (#11 - 15A) or the starter switch (#40 - 40A). There is also the chance it might be relay failure.
Given the relative ease of getting to the fuses and the relays (which are peanuts to replace), I'd check all of those are in good order before digging out the pump.
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I have a big bag of fuses and relays actually - I bought an entire panel when investigating a previous issue (which was something completely different), I'll have a play, might have time before leaving for the replacement flight.
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Good luck, hope it is that. As always, be careful when messing around with fuses/relays and always disconnect the battery if not sure, you don't want to add electrical issues as well. ;)
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Relays sometimes come back to life after they cool down a bit.
You need a star diagnosis, you can have all 3 elements of combustion but the ECU waits for the engine to reach a certain RPM and position before firing.
If those sensor are dead (the crankshaft or the camshaft position sensor?) you have no chance of starting the car even if you tow it in gear.
I would not attempt to repeatedly start the car if it doesn't seem to start, or at least let the starter motor cool between tries. I don't know if flooding the cylinder can also be a risk with electronic fuel injection.
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Thanks all. I had time to pull the relevant fuses and all looked ok, I put the larger #41 on a meter too, it had continuity. I need to wait until I'm home to test the relays.
What are the options for diagnosics, is the star system very specialist? It's currently on my drive so getting it transported anywhere will obviously cost money and time, and the car is only worth £800-1000 when running so it's on a knife edge. I do recall having a crank position sensor fault last spring when I got it, but I think it happened once or twice, so I guess that's a real possibility there.
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STAR is the Mercedes diagnostic equipment and the recommended diagnostic equipment for Smarts in general because it can drill down a fair way into what a fault could be. That isn't to say another diagnostic machine can be used but it will be less capable.
With that said, if it does have a crank sensor fault anyway, it'll be worth getting that replaced anyway, if only for that to be eliminated as a cause.
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sorry to hear that
the cars are v reliable and i've seen very few failures that would make a car un-affordable to fix.
sounds like a fuel prob to me
no key on the dash? immobiliser
engine management light would be showing if it was something that the ECU had decided was wrong (airflow, crank position etc)
JJ
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you say the EML would come on if a code is logged JJ, BUT i have seen cases where a sensor has failed but the EML hasn't come on. X-Type diesels when a cam sensor fails, there is no EML but the car will run till its switched off, then it wont start again...
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If as you say, it had an issue previously with the crank position sensor
and it was not replaced, then that would to all intents and purposes
be the first thing to get fixed/changed.
But....if it had a Star diagnostic's plugged into it, then the answer
would be plain to see (to the operative of it).
Unfortunately, this will require your car to be transported to a Smart
independant.....and the closest to you I think would be in Guildford..
Smart Car Specialist (Sasha), an alternative would be S2smarts
between Rickmansworth and Watford. Call either for advice, and
when they could fit you in...as well as a rough idea of the cost for
the diagnostics and replacing the sensor, then get quotes from
local transporters to get your car their. (I suspect SCS has a contact
who they could suggest to get your car transported to them....I do
know that S2 definitely does.)
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Many thanks for the detailed replies! I am back in the country and had a short while to test a few things before it got dark (and more importantly, I got tired).
- I put a probe stethoscope on the fuel pump while somebody turned the key, I couldn't hear it prime when the key was turned (does the FF do that?), but when it was cranking/running I heard a definite whine.
- Spraying a little bit of brake cleaner into the intake hose while it was being cranked, it ran for a short while. Then when cranking it after that (but not changing anything else) it catches and runs for a short while before stuttering to a stop - it did this several times.
- I changed both fuel pump relays with ones from my spares and there was no change, I haven't tested the ones that I pulled yet, but imagine they were fine.
- I used Torque to read off any fault codes, none were found (this was most interesting).
- I didn't remember to check the immobiliser/key symbols, and sorry my memory of what I saw before was not clear.
One important thing is that the battery is quite weak due to cranking and having the hazards one for 3+ hours, I have it on charge and will test some more tomorrow.
I'm leaning towards it being a weak fuel pump though - ie. there is enough to get a bit of pressure so it can start, but not enough to supply the engine running.
edit: I next plan to put a meter on the pump connector to check that it is getting power both when the ignition is turned on and then cranked/running.
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blocked fuel line??
water in fuel??
diesel instead of petrol??
maybe pop back to the garage you topped up with last?
JJ
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I'm pretty sure the fuel is fine, The gauge had just dropped to 1 bar and it had run fine for the whole tank. I probably filled it sometime in January.
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It's run out of fuel?
The gauges are flakey at the bottom end and can totally misread
Put 1/2 tank in first and then see.
JJ
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That was my first thought I put in half a can at the roadside (at least a couple of litres) and the gauge increased to 3 bars. I have run it down to the flashing petrol symbol before (with a petrol can in the boot!) so I think it's pretty accurate on mine.
I had half an hour this morning to have a further test - and I have just sneaked some time away at work to check my results. I found this service manual diagram for a 2008 CZ which has a similar setup:
http://mmc-manuals.ru/manuals/colt/online/Service_Manual/2008/90/html/M190100080556000ENG.HTM
I had 12V across the adjacent yellow-green and black pins (which I now know is 4 and 5, the fuel level sender), but nothing across 2-3 (the pump power) at any time. I will double check that later. Looking further at that diagram it seems the ignition switches the first relay and then the second is controlled by the ECU, so I should concentrate on monitoring the second one really. The short running and stalling yesterday (and whine I heard) was curious though, it wasn't doing that this morning. I might try bypassing that relay entirely - apply 12V directly to the pump when cranking and if the car starts and runs then it's the ECU not powering it for whatever reason.
Also to confirm on the key symbol - it flicks up very briefly when the ignition is turned but doesn't reappear at all, I assume that means all is good.
** edited a couple of times as I did some more reading **
Also a note that I'm not expecting anybody to come up with a solution, this is partly to add information to the 'pool of knowledge' as I figure it out.
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Are you sure that it is the 'key' symbol and not the 'service spanner'.
If it does vanish shortly after turning the ignition on, then it will be
the service spanner...NOT the unlock/immobiliser key symbol.
I'd still tend to think it could be the crankshaft position sensor....
we'll all have to wait n see.
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Are you sure that it is the 'key' symbol and not the 'service spanner'.
If it does vanish shortly after turning the ignition on, then it will be
the service spanner...NOT the unlock/immobiliser key symbol.
The key symbol definitely appears for a fraction of a second when turning it on, in the central dot matrix display. I think this is probably normal to show that the immobiliser was looking for and then detected the key.
I'd still tend to think it could be the crankshaft position sensor....
we'll all have to wait n see.
Cutting a very long story short, there is definitely power at the pump, what threw me was that I now assume the ForFour doesn't prime the pump when the key is turned to the 'run' position - it is only powered when the engine is starting, and when the starter is off it's powered off if the sensor data is bad. I did short the Fuel Pump 2 output pins but stopping and starting it made no repeatable changes, so I am currently assuming that it's probably ok.
Anyway I have a sensor arriving tomorrow and removed the crank angle sensor earlier. It is somewhat blocked by the air-con compressor and so I figured it was easier to move that to give better access. With shallow torx bits or a flexible drive it would be easier to get out with the pump in place, but the compressor can be moved to the side easily enough.
The camshaft sensor is the same part (MR985041), so if replacing the crank angle sensor doesn't work I'll try it there instead.
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Ok, so fitted the new sensor in both the crank angle and cam shaft position sensor locations and no change! The new sensor is Febi Bilstein, absolutely identical to those in the car.
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i wouldn't have expected that to be the issue if it turns over and runs a little when you used the brake cleaner
also i would expect EML if a sensor was telling the ECU to cut fuel or spark
have you tried the 2nd key?
have you added more fuel anyway??
the only time this happened to me was when the fuel station tank ruptured and i had 3/4 water 1/4 furl in my tank - but my car broke down within 200m
throttle valve not opening properly? can visually inspect
you have ruled out intake issues and battery/electrical by proving it fires with the brake cleaner
it can only be a fuel issue
JJ
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As JJ has deduced...it is either fuel or the immobiliser/keyfob.
The immobiliser is a separate circuit tothe alarm/unlock, and
the key symbol should not appear on the dash display at all...
leastways I've never seen it on either of my 2x CDI's or Brabus.
All I have ever seen is the spanner symbol (or 2 spanners) when
it's coming up to service time.
If you have the 2nd key, change the battery in it first (that is if it
has not been changed in a year), and then try that key to see IF
you get EXACTLY the same display and starting problem.
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The key appears very very briefly, for maybe 1/10th of a second, blink and you'll miss it :D I don't have a second key unfortunately, the owner's ex-wife had it and apparently they had an acrimonious divorce (the car was hers but he got it as the settlement, she had his nearly new Mondeo...)
Anyway I have ordered a used fuel pump from a decent breakers on ebay (£24), unfortunately too late for doing it this weekend but I'll get started anyway. If that fixes it I'll take a view on whether to fit a brand new one (Bosch is ~£125) or just stick with the used one.
Thankfully I still have the Leaf for another month or so! When that goes back I think I'll definitely get another second car so I can mess around like this without worrying about having transport. Probably a K12 Micra, I had a K11 and it was pretty decent, albeit a death trap in this day and age.
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New keys are available only from Merc- as stated on forum already. You will need a week and about 160 :o
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Yes, that's why I've not bothered to get a spare. I did call the local dealer in Guildford for a price on the parts I might need for this problem, but the parts department went home half an hour before the published time on the website. The receptionist took my details to get them to call me but that was several days ago, so for everything else I think I'll stick to Amazon Prime and eBay for reliability :p
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When you have eliminated the impossible, whatever remains, however improbable, must be the truth. You may well end up at Merc in the end. Why not try Brooklands- at least you can have a look round while waiting. They also have experience of sorting mine out!
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Hurray, we are back running!
I got a replacement fuel pump off ebay (£24, from a 2008 Colt), while fitting it I noticed the fuel level was VERY low indeed - the bottom of the pump sits in a hollow in the tank and it was just reaching the top of that. I fitted the new one and there was no change. I then went to the petrol station and got another can full and after adding that... it starts and runs fine! I was planning to do so after it was suggested earlier, for some reason I didn't get around to it.... lesson learned there.
The gauge is now showing half a tank so obviously there is a problem somewhere, I'll trace the wires for the sender and check the connections. I measured the resistance of the old and new pump senders and they are correct (112 ohms when empty, 11 when full).
One thing about the pump lock ring - my hands are far too weak to turn it by hand and drifting it with wood was unsuccessful (I broke a spline). I bought this universal tool off ebay and it worked a treat:
http://www.ebay.co.uk/itm/201544783714
I first tried it sitting on top of the lock ring but it wasn't getting enough purchase, then I moved it wider to the sides and it worked fine.
edit: Thinking about it, the resistance increases as the fuel level drops (a fail-safe setup), so a bad connection would show lower/no fuel. I'll look some more tomorrow!
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I wish you luck in resolving this last little issue that you have,
but may I suggest you undertake a secondary check; if you have
the time; and for your own satisfaction checkout the fuel gauge
(even though it's not showing the 'known issue' of flashing), and...
as a preventative measure rather than a cure, resolder the
connections shown in the Guide here :-
http://www.forfour.co.uk/forum/index.php?topic=4481.0
that way at least you'll then know you won't have that to fix in the future.
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Thanks, I'll try that tomorrow it may well be related.
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Well that was easy! Resoldered the SMD resistors as instructed, and the gauge seems to read correctly now! Thanks for the suggestion. Strange that adding the half-can of petrol on the roadside didn't work. Lesson learned to always carry a full petrol can.
(http://i.imgur.com/7hq0FEJl.jpg)
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Glad it was a straight forward and cheap fix for you.
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Thanks ! Cheap except for the flights :D I'm a capitalist though so I hold no ill-feeling towards Norwegian for stiffing me there though.
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well i may have mentioned the fuel thing hahaha ;)
if the car has run totally dry, a few ltrs prob doesn't go far in terms of filling the pipework etc
glad its all good now though
JJ
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All is behaving well and I'm beginning to forgive the car... I have used it for a few transporting jobs and my Leaf is in for a bit of body repairs so I'll be commuting in it all week.
edit: Oh and it passed the MOT a couple of weeks go. The handbrake mechanism was a little jammed/sticky one side but they fiddled with it and it freed up ok. The dipped beam HID conversion (which I replaced from an older kit which was falling apart) were apparently absolutely fine.
And I just dug out some pics from my phone!
(http://i.imgur.com/Cisnbs0h.jpg)
(http://i.imgur.com/sUp2I1Xh.png)
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nothing like getting a picture taken by the highways agency ;D