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Registered
1985 MB 500sel (Euro)
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146 Posts
Discussion Starter #1
Readers of this space might recall that some months ago I gave my 1985 500sel a major tuneup. Since then I have been happily toodeling along.

Alas, it never lasts. The first sign of trouble was when I began to have difficulty restarting after the engine was off for about an hour. First guess is the fuel accumulator, which has not been changed for 200k miles, and maybe not even by the original owner, which would mean 300k miles. (How long are these things supposed to last anyhow?) In any case, I have a new one ready to pop in.

But now, to that has been added the car just dies, starts right away, and does it again and again, at least until it gets up to normal operating temp. Then it idles without a problem at 600/650 rpm, and does not cut out, which would seem to eliminate a vacuum leak or a faulty idle air control valve (IACV).

could be the warm-up regulator(WUR) (also probably original)? The car goes to the shop next week,but would appreciate any thoughts members might have.
 

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SuperModerator
1986/1990 W126
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13,366 Posts
The accumulator is a damper too I think. So I wonder if it's all just that. Get a good quality one in there and see, i guess.
 

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Outstanding Contributor
1989 560SEC, 1989 560SEL, 1995 E420
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4,005 Posts
I would start by putting a fuel pressure gauge on there and see what is happening real time. I think you'll just be guessing otherwise. I got a pretty nice set at Harbor Freight for about $80 and have never regretted it.
 

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1985 500sel and 500sec 2012 E63 1989 Porsche 911
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5,060 Posts
my 500sec has similar symptoms


It used to start no problem, and as my mechanic had rigged the ICV in front of motor to manual adjust the motor speed by a turn off knob. My car started out with to high idle.

After getting it down it was better but because I'm cat free we wanted to run car in gas analyzer to better adjust it. After we did do that. When in starts it takes 2 minutes to come up to proper idle. Drives perfect after it levels out. But those first two minutes it sounds very sick. Very lumpy..

Just got done with the SEL that was running lumpy. That turned out to be fuel distributor. Injectors and accumulator
 

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Outstanding Contributor
1990 350SDL, "Grandpa's Roadster" Project Car
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3,010 Posts
I agree; a pressure test is in order. It will uncover either a bad accumulator or a bad warm up regulator.
 

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Registered
1985 MB 500sel (Euro)
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146 Posts
Discussion Starter #6
my face is red. it was a simple vacuum leak where one hose had come loose. We are still going to replace accumulator and fuel pressure test. thanks all.

next problem is looking for lower tie rods and bushings
 
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