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300e
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Discussion Starter #1
I have a 300e and it has been really reliable to far but I've had it sitting around for a little while (maybe 2 months) with the occasional idle to keep things turning over.

One day i started it up and it didn't sound like it was running very well, almost like it was running out of petrol, but when you revved it, it was OK so i just turned it off and went back to what i was doing.

A few weeks later i started it up again (still no changes to the engine), let it warm up and drove it to the end of my road where it started to run badly and then cut out completely. I tried starting it and it just didn't want to run, so i towed it up a hill and tried to hill start it with no luck, so i towed it back to have a look at a little later.

So i come back after charging the battery up and it started straight away, but sure enough after a while it starts running badly and then cuts out.

This is really weird, it definitely has fuel and the pump seems OK as i can hear it turning on and running, but its as if while the engine is going it slowly gets starved of fuel.

I have no idea what this could be and my dad hasn't got much of an idea either, though he seems pretty certain its fuel related.

Thanks in advance for any help anyone can provide.
 

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2011 GL 320 CDI, 2004 E320, 2000 C230, 2004 Toyota Sienna
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231 Posts
I would check if fuel gets to the injectors. Check fuel pump and fuel pump relay.
 

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gotta catch em all
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34 Posts
Distributor cap, rotor, fuel pump/s; if you even have them. Could be many causes. When was your car made?
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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17,405 Posts
Going by the behavior, it sounds more likely the fuel accumulator has gone bad. Located by the fuel pump area.
 

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2011 GL 320 CDI, 2004 E320, 2000 C230, 2004 Toyota Sienna
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231 Posts
I had same symptoms and turned out to be weak / loose solder in the fuel pump relay located in battery area. I resoldered it and works great ever since.
 

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W124 Moderator
86 190E 2.3L 16V, 2 95 320TE's, 02 S500
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12,758 Posts
With a fully charged battery, start the car and get a reading of the voltage at the battery. If your reading is anything below 13.4 volts, I suspect your voltage regulator is the problem. As voltage drops on these cars, all manner of strange behavior presents itself. The cars a very sensitive to proper, constant voltage.

The regulator is mounted on the back of the alternator, held in place by two phillips screws. Dead simple to change out in about 10 min. Not an expensive part. You don't mention the mileage on the car but I suspect it is up there. You stated it runs well for a bit with a fully charged battery. Also have a load test put on the battery.

Do this simple test before tossing money at mystery problems and keep us posted.

Good Luck,

Jayare
 

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300e
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Discussion Starter #9
Hmmmm.....

Distributor cap, rotor, fuel pump/s; if you even have them. Could be many causes. When was your car made?
1989, so pretty old and as far i know of no major repairs have been made and no problems so far.

With a fully charged battery, start the car and get a reading of the voltage at the battery. If your reading is anything below 13.4 volts, I suspect your voltage regulator is the problem. As voltage drops on these cars, all manner of strange behavior presents itself. The cars a very sensitive to proper, constant voltage.

The regulator is mounted on the back of the alternator, held in place by two phillips screws. Dead simple to change out in about 10 min. Not an expensive part. You don't mention the mileage on the car but I suspect it is up there. You stated it runs well for a bit with a fully charged battery. Also have a load test put on the battery.

Do this simple test before tossing money at mystery problems and keep us posted.

Good Luck,

Jayare
Yes this seems very interesting as the only thing done is charged the battery, perhaps when it went flat from trying to start it something went wrong or there was an issue before hand that has only has risen, i'll also check that connection with the fuel pump relay, note this is a right hand drive car, originally from south africa. Its done just over 300,000km but everything else has been running like a charm so far (good ol' Merc's)

Going by the behavior, it sounds more likely the fuel accumulator has gone bad. Located by the fuel pump area.
damn, i just sold that part off my spares car. Is there some way to check it?


Thankyou everyone for your responses its a huge help
 

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'89 300TE, '79 450SL, '01 ML320
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damn, i just sold that part off my spares car. Is there some way to check it?
Yes, pinch off the small line that returns to the tank, and disconnect it. I use a small needle nose
visegrip, a small amount of gas will drip out. Put a pan under just in case and turn the key on.
The nipple on the accumulator should remain dry, if not the diaphragm has ruptured and is NG.


Fish
 

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300e
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Discussion Starter #11
Back after xmas

Ok guys, sorry i couldn't reply, xmas and things had me caught up. I've tried everything suggested to no avail. fuel is definitely getting to each injector.

Something i have to press is that when the car starts up it runs fine, really well in fact, but consistently after each starting, about when it warms up, it will start to miss.. then more and more then it eventually cuts out as if lack of fuel or incredibly bad timing issues.

This whole issue is really really really starting to get me annoyed as i still can't figure out what the hell the problem is, especially after it was just sitting around.

Again thanks for the help guys, much appreciated

oh and merry xmas/happy new year to you all
 

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Hi there did you ever get to bottom of this as I now have same problem with 1986 300e 6cylinder any help would be so much appreciated thanks
 

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W124
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Ciaran, Why not start a new thread with your problem. This thread is long dead and I doubt you will hear back
 
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