Engine just stopped
Driving along quite happily at about 30mph, engine nicely warmed up, when it cut out. Pulled over to the side of the road, put auto into P, turned the key and engine started first time as normal. Set off down the road happy as you like. Stopped to do a bit of shopping after which car started as usual and got home, no problems.
Reminded me that exactly the same thing happened a couple of months ago.
Car has plenty of fuel in it.
Anyone any ideas?
is every thing nice and dry
Could be one of the fuel-pumps or fuel-pump relay on the way out.. Or cam-shaft sensor, which times the ignition. Or dodgy contact on ignition switch. Guess you had more than 1/4 tank of fuel?
Ah thanks Ian.
Will have a good look around in the morning.
Try here for Bosch parts for the 300GE
eg Fuel Pump:
then here:
Thanks Arnie,
Is there a generally accepted life expectancy for these fuel pumps?
£108 each doesn't seem too bad (they're probably 25 years old) - unless I should really expect them to last forever.
The price of £82 includes VAT and delivery. (also including new one-way valve)
Hard to say what the expected life of a fuel pump is. I've had one fail on an SL with 9k miles due to bad fuel, gumming it up,
I had to change a pair on a 300GE after 7 years and 60k miles.
On my 20 year old 300GE they appear (touch-wood) to be still fine, although the one-way valve on the top pump is no longer sealing allowing fuel to drain back to the tank, requiring longer cranking to start.
I think when they fail, you may see intermittent operation and perhaps reduced fuel-pressure.
They have brushed motors and eventually the brushes will wear out, so probably worth changing them for peace of mind.
Check out the distributor cap and rotor arm initially; these have a tendency to burn out and common around every 70 - 80000 miles mark.
Engines can suddenly die with burnt out caps and rotors.
Establish first the cause of engine kill, is it an electrical ignition issue or a fueling issue. Ignition checks are easier and quicker to proceed with.
When mine developed this issue I checked for a spark, as pointed out dizzy's have a limited life, I'd say only 40k, I checked the fuel pump, this was fine and it turned out to be the fuel pump relay, which Kevin James of Stuttgart Motors in Pontypridd gave to me, thanks again Kev.
Thanks to all for your continued interest.
Hmmm - trouble is that the problem at the moment is so short term. Engine dies, I pull over to the side of the road, turn the ignition off, turn the ignition back on, engine starts straight away and off I go again.
Presumably if I were to check any of the items specified above after I pulled to the side of the road then they would all show as working normally.
So, do I replace one of the items then wait to see if fault happens again and if it does then I replace the next item on the list and so on until the fault never recurs? At the current rate that could take several years.
I know about distributor cap problem (I've had two 300TEs in the past) but when that was the problem then restarting always used to take time. Certainly not, turn the key and off we go. Just checked back on service history and note that rotor and dist cap were replaced just before I purchased a year and 3,500 miles ago so am putting those two items at the bottom of my list.
I'm definitely not mechanically minded but think maybe I should start with the fuel pump relay (hopefully not overly expensive and pretty much plug and play so I could definitely do that myself so no labour cost) and then wait to see if fault recurs. If it does then maybe the 2 fuel pumps and then if it happens again back here for more advice.
Does that sound sensible or is there a better first step?
.
relays are plug and play, widely available on e-bay but better to borrow one and check it before buying in case its something else, where do you live
http://www.ebay.co.uk/itm/Fit-Mercedes-W124-W201-W126-R107-Relay-New-Fue...
I'm halfway between Brighton & Eastbourne.
But as, so far, the problem has only happened twice in the past couple of months and doesn't last then borrowing one to check isn't really going to work.
For about £30, I'm happy to treat it as a "service item", replace it and see how many months go by before I realise it hasn't happened again - or otherwise, in which case I'll replace the 2 fuel pumps and treat them as once in 25 years service items too.
Before you know it, I'll have a brand new G Wagon.
OK - so now I've had a bit of time to think about this (always a good thing to do before spending money in my view).
Am I correct in thinking that the fuel pump relay only really does anything at switch on and again at switch off (i.e. it's being bypassed when driving along normally)?
If so then surely this can't be what's causing the "engine stopping when driving along problem" - or can it?
No, the fuel pump relay operates continually. It operates the pump for a couple of seconds when the ignition is first switched on to prime the fuel system. Then it operates continually, when it sees pulses from the cramshaft sensor.
It might be a blocked fuel filter.
If your filter has not been changed for some time it can start to break down inside and debris suspended in the fuel can temporarily block the mesh around the filter outlet shutting off the fuel supply to the engine.
When the engine stops the pump cuts off and the pressure inside the filter is released which allows the debris to sink away from the mesh. When you turn the ignition back on the pump runs briefly to re-pressure the system through the now clear filter outlet and the engine fires up as normal.
Depending on how much debris you have inside your filter the engine could run for some time before the filter outlet becomes blocked again, it is quite a difficult fault to diagnose.
It might be worth fitting a new fuel filter to see if that helps.
Thanks to both.
Fuel filter changed at last service (only a few hundred miles ago).
OK - back to the idea of fitting new fuel pump relay and seeing how that goes.
have you physically examined the pump, yours is under the rear near side arch, I had one on a ge280 who's externals had almost completely corroded away but still worked until it failed
Probably sounds stupid - but no I haven't. I kind of hoped that the garage that changed the fuel filter would have said something if it had been that bad. But maybe not. I think my 300GE has 2 fuel pumps. Are they both in the same place?
And now checked invoice and notice they fitted 1 fuel filter - as there are 2 pumps should there be 2 filters? 
Probably not related to this, but it's worth cleaning the idle air valve from time to time, If it becomes sticky with dirt, It can cause stalling when removing foot from accelerator, such as when approaching junctions. It's located under the air-filter pan and heldy a clamp with two screws and two rubber hoses. A clean-out with some small amount of petrol petrol or WD40 through the ports and then a drop of engine oil to re-lubricate the internal rotating valve (visible trough the ports and moveable but shaking the valve with a twist motion:
Thanks Gav,
But if it was either the rotor arm or dist cap (or both) would you not expect starting or running generally to be a problem?
This one starts on first turn of the key (no, really!)
Oh dear - engine stopped again today and wouldn't start again until left for a while instead of straight away (as previously).
Had a proper look around engine compartment in good daylight and dsitributor cap has a nasty crack in it so that looks as though it is probably the culprit.
About to order Distributor Cap, Rotor and Insulating cover but want to make sure I get the correct parts - the number on this site http://www.mister-auto.co.uk/en/distributor-cap/bosch-1-235-522-384_g692_a0301!235!522!384.html for the distributor cap doesn't match up with the one that is already fitted to my car (1 235 522 384).
Anyone able to confirm what the correct numbers for these items should be.
Also realised that there is a shield missing from the front of the engine that goes over the front of the cylinder head down over the distributor cap. I'm guessing it's plastic. Anyone know what the correct name for this part is and what the part number is please?
Mark,
The numbers you have written do match ?
Doh am I stupid, or what???
The MB part number on the distributor cap that is cracked is 103 158 05 85 whereas on the Mister Auto site it says their Bosch part is to replace the original MB part number 103 158 00 02 - 103 158 00 02.
Ha ha ! No pal you ain't stupid !
These part numbers can be bloody confusing and Bosch often have their own numbers.
Maybe different merc models and engines share parts but use different numbers. It's probably the part you need but how can you be sure ?
One of the goodfellas might know ?
Glad you found the potential problem.
Euro Car Part part-numbers below
Bremi is an OEM brand:
(Check prices also with MB. In some cases they may be cheaper)
New distributor arrived.
Rotor Arm (ordered from same place - Mister Auto) though is on its way from from Belgium - go figure.
So first attempt at solving problem delayed for a few more days.
Can anyone help with correct part number for the fuel pump relay - for my 463 300GE SWB and where exactly to find it? I know where the relays are but which one is the fuel pump relay?
Thanks Neil,
I'm still hopeless at searching for what I need.
So, G now has nice new distributor and rotor arm.
Started first time (as usual) and left engine running, about 4 minutes later the engine stopped. Waited a few minutes and she started again, 2 or 3 minutes later she stopped wouldn't re-start immediately.
Awaiting arrival of new fuel pump relay to see what effect that has.
In the meantime I shall put another 10 litres of petrol in tomorrow just in case low fuel (1/4 tank) could be causing problem.
More updates to follow.
check for air leaks, these can be masked at start up because of extra fueling and only appear when engine is up to temperature, you can confirm this with a spray can of easy start, spray this around the inlet manifold if you have a leak then the engine will speed up with the mixture entering via the leak confirm by checking the plugs which will show as operating lean
Thanks for suggestion - will have a go at that tomorrow.
But if it was that sort of problem would the engine not stutter and then die? This one is happy idling for a couple of minutes after starting and then just stops - as though I'd turned the ignition key off.
Fuel guage showing between 1/4 and 1/2.
That is indeed strange. I would focus on fueling and ignition.
On the fueling front, it could be
- fuel pump (but there are two)
- fuel filter blockage
- " 1/4 tank " problem
- perforated fuel accumulator, returning fuel directly to tank (resulting in low pressure at fuel distributor)
- fuel-pump relay
- over-run fuel cut-off micro switch
On the ignition front, it could be:
- crank-shaft sensor, which provides ignition timing
- Engine Speed Sensor (provides TDC, fuel-pump cut-off and tacho signal)
- EZL ignition module
- faulty ignition coil
As the engine apparently dies suddenly, its most likely an electrical problem. The fuel-pump relay is a good place to start. Then, crankshaft sensor
Crankshaft Sensor:
Speed Sensor
This may also help
http://www.peachparts.com/shopforum/tech-help/287384-m103-suddenly-died-fwy-70mph.html
Welcome back to the continuing saga - all your contributions really are appreciated.
So, today the problem has developed somewhat. The car now won't start at all. Turn the key and starter gets engine turning over, release key and engine stops.
Had a good check over battery and earth connections and they all seem to be good.
Removed rear nearside wheelarch liner so I could get a look at the fuel pump(s) and have attached photos. But are there 2 pumps? Bear with me because I am not a mechanic but there don't seem to be 2 items that are identical (and I assume that if there were 2 pumps then they would look the same). I also assume that one is the pump, one is the filter - what is the other item?
Anyway, I had someone turn the ignition key whilst I listened to the fuel pump and there is definitely no noise, either when ignition on or when starter motor starting. I remember hearing that knocking the fuel pump with a hammer can work, I tapped it with handle of screwdriver as I was worried about how hard I could get away with hitting it.
Still waiting on fuel pump relay arriving - to give that a try (fingers crossed as I'm worried that I'm reaching the limit of my abilities).
Hi
Did you get my pm
If the engine does not spark it wont send fuel. I doubt its the fuel pumps or relay. I would bet on crank sensor for ignition system or ignition module. It will be something simple. Has it an aftermarket alarm fitted???. People often do this and tap into a wire that has a lot of current going through wire. Alarm cant cope with this
Did you try the plug test i said. If no spark no fuel will be sent. I think you are close to the fault and once you replace something you will have no problems
Furthermore
When you first turn the key to start the pumps will prime for a very short while so check that too
Then if it does not start up the pumps wont either so i recon sparks department
Thanks Gaz,
Yes got your PM - waiting for neighbour to come back tomorrow as I know he has spare spark plugs for that test.
No noise from pumps when turning key. On my old 300TE I used to get a clicking noise for a while should the G sound the same?.
Yes, there are 2 fuel pumps. One is under the rear wheel arch, next to the filter, and the other is at the bottom of the fuel tank, on the outside, hidden by the tank protection plate. The fuel pumps work in series with one another.
You also have a fuel accumulator - the small thing, next to the filter.
As has been mentioned, the fuel pumps should run for about 1 second to prime the system when the ignition key is turned to position-2? You'd here a short 1 sec buzz if standing near the rear. The fuel pumps will only continue to operate if there is a signal from the crankshaft sensor, to show the engine is running, or cranking.
The most common failure is the fuel-pump relay, so begin with that.
Do you have the service manual? This will locate the relay for you.
The relay can be removed and the correct two pins in the socket bridged to run the pumps. These correspond to the relay contacts, which should be indicated on the relay casing.
If you can then start the engine, you will have found the problem. New relay required.
By the way, good time to change the fuel filter, whilst at it..
Thanks Arnie,
Waiting on arrival of new fuel pump relay - promised for Monday or Tuesday.
I have located the relay but it has a different number to what I was expecting. The number on this one is 003 545 38 05 and it has six pins on the top row but only 3 pins on the bottom row (where I was expecting to find 4 pins).
It doesn't have a diagram on it - but all the pins are numbered - do you know which pins/sockets I would have to bridge to see if the engine would start?
Fuel filter changed at last service (just a few months and a few hundred miles ago).
the larger of the two "pumps" is the fuel filter, worth changing while you have it accessible, the smaller of the "pumps" is the real electric pump, there is also a second one as Arnie has mentioned
Pinch a plug out of lawnmower as with all the rain it wont be needed anytime soon
Another little check is the pipe to the fuel pumps. Does it look good with no splits or corrosion
I have seen this on a scabby farm g wagon and the pipe was holed so it could not suck any fuel just air
All parts will be reasonable. Crank sensor, ignition module and fuel pump relay. It will be one of those for sure
Damn - lamnmower plug - why didn't I think of that??? I have three of them.
Anyway, courier confirms that fuel pump relay will be with me sometime tomorrow morning - so fingers crossed that solves the problem.
A three cylinder lawnmower ehh
That must have a big cut lol
'Twas the fuel pump relay !!!!!!
Fitted new one and started up straight away, left it running for about 15 minutes, then took it for a run up to the end of the road and back and later 20 mile round trip to the dentist (maybe subconsciously hoping it would break down on the way).
Many thanks to all of you who offered advice, suggestions, information.
G now has brand new distributor cap, rotor arm and fuel pump relay and is driving even sweeter than before (maybe now it will even do more mpg).
Gavin says that, going by the existing relay part number, it was the original so I guess not bad for a 25 year old part.
Mark
Yes they were well built the old mercs. Dont mind spending a bit on mine ,well a lot as like you say 25 years running is not too bad at all by any standards
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Actually wasn't raining today and had already driven 6 miles, stopped to shop at Tesco, then driven 1 mile to drop someone off then about 1 mile further along the engine cut out. Engine bay nicely warmed up and dry by then.
Well over half a tank of petrol at the time.
If it was one of the fuel pumps would it then restart with first turn of the key?
Is there just the one fuel pump relay? How much could one of those cost? Might it be worth replacing "just in case"? I'm guessing it's only possible to be sure that's what it is when it's not working and I'd rather that wasn't at 1 o'clock in the morning in the rain miles from home.