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1995 S320 LWB
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5 Posts
Discussion Starter #1
Hello all, I was hoping to get some help on a issue I was having that has now become a bigger issue. Over the last few weeks my car (95 S500) has been having a rough idle and almost sputtering and shaking. I did a full tune up six months ago(wires,cap,rotor,filters,EXPENSIVE) and car had been running great. Yesterday i went to check some fuses in the trunk and while the car was running I pulled the fuel pump fuse and the car conked out and wont start now. Any idea?? what happened..
 

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1989 560 SEL, 1993 400 SEL, 1986 420 SEL, 1977 450 SL, 1984 300D, 1981 380 SL, 1983 500 SL
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606 Posts
First, I would put the fuse back in, then go thru the reset procedure. Turn the key to the "ON" position for 5 minutes(Make sure it is 5 minutes) then turn it to the "OFF" position for 1 minute, then try to start the car. It should reset itself and start.

The other problem could be a bad fuel regulator or even just one bad fuel pump. My 400 sel was not running correctly and I found that one of my fuel pumps was not working at all, so I removed the bad one and just connected the good one only and now it runs better than it ever did. Replace the fuel filter also while you are working under the car on the fuel pumps also.
 

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1995 S320 LWB
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5 Posts
Discussion Starter #3
will try when i get home. Is the fuel pump and filter a easy job?? Do yoou know the location of them?
 

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1989 560 SEL, 1993 400 SEL, 1986 420 SEL, 1977 450 SL, 1984 300D, 1981 380 SL, 1983 500 SL
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606 Posts
It's an easy job indeed. Fuel pumps and Filter are located by the passenger rear axle. They have a black plastic cover over them. Try the reset first to see if that solves your problem. Make sure that you leave the key in the on position for 5 minutes. I even use a timer to perform this task but that's just me. Make sure that the fuel pump fuse is indeed good and when you pull a fuse, make sure that the car is turned off and also turned off when you put it back in. If you haven't changed the fuel filter in a while, this is something you should do whether the reset works or not. You can test the fuel pumps by disconnecting the positive lead to both pumps, then get an 8 foot length of wire(I used 16 gauge regular black wire that I had left over from re-wiring my trailer) and have someone hold one exposed end on the "Positive" terminal of the battery and take the other end and touch it to the "Positive terminal" of each pump individually. The "brown" wire on the fuel pumps are the "Ground". Make sure you take both "Positive" wires off the fuel pumps before you perform this test. You will hear the pumps spin if they are good. They will do nothing if they are bad. You will not hear anything if this is the case. Good luck with this and let me know how things work out.
 

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Registered
1989 560 SEL, 1993 400 SEL, 1986 420 SEL, 1977 450 SL, 1984 300D, 1981 380 SL, 1983 500 SL
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606 Posts
Is it running now? If so, what was the problem with it?
 
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