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1998 ML320
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Discussion Starter · #1 · (Edited)
Yesterday morning when I tried starting my ML320 it just kept turning over but not starting. I did a search and it seems like it could be the CPS (which I changed about a year or 2 ago), the ignition or the fuel pump. Is there any way to confirm which one it could be?

Battery is fairly new so I figure that's not the issue.

BTW, for the last couple of days, the jeep has been running bad and not accelerating as it should. At time it would barely move when I press the gas and then it would shoot off when it catches itself.
 

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Dallas, Texas
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Registered
1998 ML320
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17 Posts
Discussion Starter · #4 · (Edited)
Tested the plug on the fuel pump today and no current is going to the pump. The relay is fine so what else could it be?

Also, I am getting codes P0100, P0170, P0400 and P0410.
 

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What happens when you put amp meter across terminals 30 and 87 of fuel pump relay?
 

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1998 ML320
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17 Posts
Discussion Starter · #6 ·
My brother only used a test light to see if it was getting power and it was. I will try the amp meter tomorrow.
 

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Relay is only closed when first turning key on to prime fuel system, cranking or running. Putting meter across 30/87 bypasses relay so you can search for power loss down the line. Piece of wire with inline fuse and spade connectors woks just is well.

Please, update your profile with vehicle and location info.
 

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1998 ML320
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17 Posts
Discussion Starter · #8 ·
OK, just for further clarification, why do I need the amp meter again? If the test light indicates that it is getting power when I crank the truck, what is it that I'm trying to test for again?
 

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Dallas, Texas
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You are trying to check fuel pump power consumption or lack thereof if pump is bad. Have you checked if pump has good ground?
 

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1998 ML320
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17 Posts
Discussion Starter · #10 ·
I pulled the connector off of the fuel pump and put the test light on it and there is no power going to it at all.
 

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I pulled the connector off of the fuel pump and put the test light on it and there is no power going to it at all.
With fuel pump relay bridged? Cranking?

You need to get little more involved. At this pace we will not get it running before Christmas :(
 

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2000 ML320
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74 Posts
Like Witek said are you testing it while your cranking the engine? You're going to need two people. There isn't supposed to be any power going to the fuel pump even though the key is in the on position unless the engine is cranking or running, its a safety feature.
 

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1998 ML320
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Discussion Starter · #15 ·
Just remembered also that when I took off the plug that connects to the fuel pump, the end wire broke off so I need to replace that end connector too. Where can I get that from?
 
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