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  #1  
Old 09-23-2009, 12:29 PM
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Fuel Accumulator Question

I suspect that my Fuel Accumulator is going bad on my '93 190E 2.3. Occasionally during hot starts there is a sound of gas re-entering the gas tank, a gurgling noise, and the car is running like it's getting low fuel pressure for a few seconds, then it smooths out and runs fine.

Theoretically, should fuel be able to come out of the fuel accumulator return line? If it does, it is a sign of a ruptured part?

At this time, I have the return line disconnected at the fuel accumulator and the main line blocked off. I put a clear hose on the fuel accumulator output to monitor any fuel coming out. Of course the car is starting good and idling perfect during the tests, but when I turn the engine off, there is some fuel coming out into the clear hose. It's not a lot, but I'm just wondering if this is something that should occur.

Thanks,

Dave

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  #2  
Old 09-23-2009, 12:39 PM
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No fuel should come out under those test conditions.
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  #3  
Old 09-23-2009, 01:16 PM
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Thanks M.B.DOC, I went back and tested the fuel accumulator by just cycling the key on and off a few times and I get fuel coming out into the hose.
Does this sound like a ruptured diaphram?
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  #4  
Old 09-23-2009, 01:58 PM
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Sounds ruptured to me...

The M104 fuel pressure regulator is pretty similar - if it leaks fuel, the diaphragm is ruptured.
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  #5  
Old 09-23-2009, 02:04 PM
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Hmm, I'll have to try that on my car......if it leaks I have my culprit!
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  #6  
Old 09-23-2009, 02:11 PM
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Originally Posted by pawoSD View Post
Hmm, I'll have to try that on my car......if it leaks I have my culprit!
Just curious, what are your symptoms that you suspect you have a defective fuel accumulator?

If you have a clear hose, it helps to see the fuel coming out. I even removed the fuel accumulator and put the hose into a pan of water. When I applied compressed air into the input of the FA, air bubbles came out of the hose.
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Old 09-23-2009, 11:53 PM
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Quote:
Originally Posted by slk230red View Post
I suspect that my Fuel Accumulator is going bad on my '93 190E 2.3. Occasionally during hot starts there is a sound of gas re-entering the gas tank, a gurgling noise, and the car is running like it's getting low fuel pressure for a few seconds, then it smooths out and runs fine.

Theoretically, should fuel be able to come out of the fuel accumulator return line? If it does, it is a sign of a ruptured part?

At this time, I have the return line disconnected at the fuel accumulator and the main line blocked off. I put a clear hose on the fuel accumulator output to monitor any fuel coming out. Of course the car is starting good and idling perfect during the tests, but when I turn the engine off, there is some fuel coming out into the clear hose. It's not a lot, but I'm just wondering if this is something that should occur.

Thanks,

Dave
having the same issues on the 2.6. Gonna install a new accumulator in it tommorow and see if that fixes the problem.
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  #8  
Old 09-24-2009, 09:30 AM
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Fuel accumulator

The accumulator has a spring diaphram internally that maintains system rest pressure for a short period of time after the car is shut off. Both sides are exposed to liquid fuel and the diaphram travel back and forth during system operation. When the car is at rest the diaphram relaxes and returns to a rest position. When the car is started a small amount of fuel is pushed out as it re pressurizes. A leak would have continual fuel leakage from the vent line while running.
Bill
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  #9  
Old 09-24-2009, 10:26 AM
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Originally Posted by Bill Adkins View Post
The accumulator has a spring diaphram internally that maintains system rest pressure for a short period of time after the car is shut off. Both sides are exposed to liquid fuel and the diaphram travel back and forth during system operation. When the car is at rest the diaphram relaxes and returns to a rest position. When the car is started a small amount of fuel is pushed out as it re pressurizes. A leak would have continual fuel leakage from the vent line while running.
Bill

Thanks Bill, I understand how it operates but I didn't know it was normal for fuel to pass the diaphram. According to what you have described, mine is acting normal.

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Old 09-24-2009, 11:05 AM
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I actually changed one many years ago feeling as you do, then discovered I was wrong in my diagnosis and had to remove it. As for passage fuel doesnt pass the diaphram, it is lower than the fuel level in the tank and just fills the line and chamber due to gravity...... I think
Bill
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  #11  
Old 09-24-2009, 01:54 PM
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put the new accumulator today and it didnt fix the problem so I must my diagnosis wrong so back to the drawing board
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  #12  
Old 09-24-2009, 03:50 PM
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Quote:
Originally Posted by Bill Adkins View Post
I actually changed one many years ago feeling as you do, then discovered I was wrong in my diagnosis and had to remove it. As for passage fuel doesnt pass the diaphram, it is lower than the fuel level in the tank and just fills the line and chamber due to gravity...... I think
Bill
I understand what you are stating, but for testing purposes I disconnected the line going to the fuel tank and plugged it so I could observe what was coming out of the Fuel Accumulator. I put a clear line on the rear of the FA and fuel was coming out, not a lot, but even if I turned the ignition on/off a few times to cycle the fuel pumps, fuel would come out.

So, did you ever isolate your problem?

Dave
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  #13  
Old 09-24-2009, 04:19 PM
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Yep I did, it was an occasional hard starting problem that was caused by water in the fuel. It caused a small accumulation of rust in the fuel pressure regulator causing irregularities in initial start up fuel pressures. Took a cople of days to isolate but I did get it.
Bill
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  #14  
Old 09-24-2009, 05:13 PM
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Originally Posted by Bill Adkins View Post
Yep I did, it was an occasional hard starting problem that was caused by water in the fuel. It caused a small accumulation of rust in the fuel pressure regulator causing irregularities in initial start up fuel pressures. Took a cople of days to isolate but I did get it.
Bill

Good information....the fuel pressure regulator isn't discussed much on forums.

Now for the real question, how did you determine that there was rust in the FPR?

Dave
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  #15  
Old 09-24-2009, 05:44 PM
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My issue is completely isolated to warm starts with the car having sat off for more than 30 minutes but less than 3-4 hours. Cold starts are fine, warm starts within the first 20 minutes are fine. Otherwise it sputters for a second or starts and dies, then fires right up on the second try. My injectors are up to be replaced to solve this....hopefully it does

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 88k - mine - (OC-91,200)
'17 Metris(VITO!) - 16k - wifes (OC-17k)
'01 E320 Wagon - 159k - mine (OC-160,000)
'01 E320 - 179k - dad's (OC-182,500)
'07 E350 Wagon - 133k - dad's (OC-132,500)
'01 SL500 - 52k - dad's (OC-52,000)
'16 E400 4matic Sedan - 70k - Brothers (OC-72,000)
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