fuel pump relay
Could somebody give me an idea where I might find the fuel pump relay on my 463 ges petrol. Do I have to remove the fuse board as I see there are screws there and it might be a flap or is it in the bay?
Thank you.
I think you will find on the near side of the foot well, under the glove box.
You will need to undo the small piece of carpet cover, the fuse box will be under. Unscrewing the fuse carrier will allow the fuses to drop down and this gives access to the relays, you will find your fuel pump relay amongst them. Switch on the ignition only and with your hand on the relay will identify the relay as you will feel the buzz in it.
Sorted I think. So simple......
Stalling problems can be caused by worn distruibutor brush, this usually shows up at about 70,000 miles.
Other faults could be worn spark plugs, dirty air fitler, old fuel filter, fuel mixture out of adjustment or clogged idle speed regulator.
Even a moist distributor cap could cause your fault.
But it looks like you have sorted your problem but do not say what was the cause.
Yes would be v. interesting to hear how it was solved?
Oh right, sorry for the delay, I work away occasionally and this week was one of those times.
Forgive the non-technical descriptions but you're right on the button Pistonhead.
The problem is apparently a variation of a problem I had a year ago. The car stopped one time and I got RAC’d into my garage. The mechanic straightaway looked at the distributor cap in which the contacts were corroded (no moisture). He changed it, all went well. That was about March last year.
He serviced the car in November last and noticed the distributor points were corroded again (no moisture) and changed it under warranty.
Due to the huge mileage my new job was going to incur I had bought a 50mpg car for work in October and the G is used now only by my wife for short runs about five or six times a week maximum 3-4 miles a trip whereas it was used daily otherwise for longer runs.
On Saturday the RAC mechanic took the distributor cap etc apart after checking the spark and coil and the thing was corroded again and full of moisture. A clean up and all is well. He reckoned the short runs with the engine never getting fully warmed and the fact the car is always garaged exacerbates the condensation and corrosion problem.
It’s that simple if his analysis is correct. Since the service in November I reckon I’d done less than five hundred miles.
I seem to remember having to change the distributor cap much less often in the eleven years I had the 230 before although this is the third in the four years I’ve had the 300.
Anyone want a fuel pump relay? That was all I could come up with knowing that there was a new distributor cap on the car less the 6 months old and not expecting a problem with it.
Hope this helps.
aha that clears things up! thanks
Is the engine 12 or 24V (M103 or M104)?
Damp in the dist cap is fairly common in M103-engined vehicles. I've had it a couple of times (3 & 2 yrs ago) in my 300SL and about a month ago in my 300TE. Never happened in the 300SE I had, though.
Apart from the fiddly business of getting the bottom bolt out of the dist cap, it is a simple check if you ever notice a lumpier idle than usual and coughs and splutters (and, worst case, stalling) on applying throttle when at low revs.
A quick spray with WD40 and a wipe round with a rag will sort it. Unless it is a different prob, of course. I always carry the required allen key, just in case.
That's exactly what I'm going to do. I just have to find the time to get a short ratchet and key which seemed to make the job very easy for the RAC guy.
What is the puzzle for me is the corrosion, or patina, that builds up so readily on the contacts.
None of this is a bother once known. On the 460 it was the rubber grommits in the selector rods and I just got good at getting underneath and replacing them, or even better, checking regularly when in clothes that were dirty before I set out.
gelaendewagen if that fuel pump relay was bought new then i would be interested, please send me a private message or reply on here if it's still available!
Update as this might be of some use to someone else.
The problem re-occured a few weeks ago after a few months and very few miles.
G stopped dead in the road and the RAC were called. I had my 'clean the distributor cap' kit with me, did the business and the car had started after my ministrations - then it stopped a few moments later wouldn't even turn over.
RAC mechanic checked battery, fuel flow, spark at plugs with a tester etc engine dead.
He took the top off the ignition coil and spotted a little carbon at the top under the waterproof cover. He reckoned the coil had been producing a weakening spark (apparently this can errode or corrode contacts in the distibutor cap) then finally it gave up the ghost.
He suggested we wait while it cooled, we did, it started and i got it into my garage.
I changed it and so far so good. He reckons this is quite rare and he was lucky to see the carbon, the spark at the tester he used on the plugs doesn't show the strength of the spark accurately just that there's one present.
I hope this is the answer to the problem, going on a nice long trip to Wales for a few days which might indicate success or failure.
hope this might be of use to somebody else.
Thanks for posting the update...I never heard someone here posting about a coil failure on the M103, but I do recall one on an M110 (280GE).
I'll inspect mine for any carbon, as my problem has recurred (but always runs for a longer period after shutting down).
Problems can also be related to the camshaft/crankshaft position sensor, which provides the timing signals for the ignition coil.
Thanks for the input Arnie.
So now I have the following suspect:
Fuel pump relay (~£75)
Ignition coil (€88)
CPS (€118).
I hope the problem manifests itself more often (or disappears altogether) to allow diagnosis...nothing as annoying as diagnosing something that only happens so often, with no apparent cause.
The CPS is also used as the source for the RPM indicator. If you have a faulty CPS the rpm indicator will tend to read zero during cranking, instead of 100 or so rpm. There is also a an output on the diagnostic socket that gives access to the signal for more accurate measurement. On my G300, the problem was very intermittent at first and hard to diagnose. I'd checked all the relays, cold-start valve, injection systems, distributor etc, but it wasn't until the problem became more severe that I traced the cause. Since new, the engine would always require a long cranking cycle to start, but at the end it would either not start at all (fast cranking with no signs of ignition) or start with misfiring.
If you have access to a new ignition coil for a good price, I'd change that anyway since a faulty coil could damage the transistor switching unit, which is a lot more expensive to replace. Over time, the enamel insulator on the coil wiring can deteriorate, eventually leading to shorted turns with resultant higher current draw and lower output voltage for the spark.
Update on my situation here...
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Pistonhead,
yes found the relay thank you. Got one, changed it, took the car for a run but same problem remains.
In case you haven't read previous thread the car will run fine until I stop for a light or whatever then stalls. It's a 3 litre pertol auto 92/3. Others on the group have had a similar intermittant problem and suggested this was a good place to start.
The battery was flat today as the car had been standing three weeks after getting back home when the problem occurred last time (many starts on that journey so I guess that drained it).
I bought a power pack today which seems to be fine and has turned the car over so I drove it away to get some charge into the battery. I got a half mile to the first lights but it stalled. With the power pack I've been trying to start the car and the engine turns over to no avail.
RAC are called and I've come home to wait for them. I suspect the bloody thing will start when they get there.
Will keep you posted on that but am stuck on anything else to have checked. Been to my mechanic who of course runs around it it for a day, twice now, and the car behaves perfectly.
Any suggestions gratefully received.