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2000 ML320
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182 Posts
Discussion Starter #1
Hello Folks,

it all started last week when my car suddenly died on my at a stop light, throttle was erratic at best, I was lucky to get it in to a parking lot for a tow.

pulled the codes and the passenger side was misfiring at the same time, figured to replace the cats- finished that up last night, cleared all the codes, started the car- that's where the fun begins!

it was actually running, although rough- but not bucking like the multiple misfire i was experiencing earlier. As soon as I touch the gas pedal, the RPM drops and the engine cuts out, with battery light coming on before all the other lights. Still no CEL.

I pulled the MAF run the car, it dies right off and code for MAF comes up so I know I'm not crazy.

Also, there was no freeze frame data saved after the cat was replaced.

there is fuel and spark going to the engine, I'm going to buy a fuel pressure gauge tonight to make sure that's sufficient. (replaced the spark plugs last year with factory plugs, and my faulty plug wire was no where near this bad and as 43sqd says "what are the chances of all of them failing at the same time")

I'm thinking vacuum leak, but I have no idea where to begin with this, I was researching vacuum leaks last night around 10:00 so there was little light to explore the engine, and of course I'm at work all day today! I did notice a medium-high pitched whistling sound coming from the engine, but i'm not sure if that's regular and just more noticeable with the cover off and the hood up.

Thanks for the trudging through, and i'll post more as I get some time with the car tonight.
 

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Registered
2000 ML320
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182 Posts
Discussion Starter #3
spark plugs are in good condition, forgot to mention that- they are easy to get to when the wheel liner is gone!

i always fill up with 92 octane since I bought it. the gas station i go to does have ethanol in it though. i keep reading short comments about ethanol and high compression engines, but can't quite figure out a connection.
 

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2000 ML320
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182 Posts
Discussion Starter #5
these are not the same symptoms exhibited when i changed my CPS, it was only effected when engine was hot.

i snooped around and there were not any broken/disconnected vacuum hoses. i will pick up a fuel pressure gauge tomorrow, the canadian tire is a bit far for a walk tonight!

Still no CEL.
 

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Premium Member
02 ML320 06 ML500
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17,104 Posts
here is a video of me trying to start it.
This could be a few things, one of which could be a DAS (Drive Authorization System). After trying to start the truck look for START ERROR in the odometer window.

Insert the key into the ignition, turn to position #2 and look at the LED on the dash. It should blink once indicating that the key has been recognized.

If it doesn't blink, either the key or the DAS module is faulty. If you have a second key, try it. If both are not recognized, then the DAS module needs replacing.
 

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Registered
2000 ML320
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182 Posts
Discussion Starter #8
i tried it this morning, and the LED does blink once and no Start Error messages.

i did notice a buzzing sound in the engine bay, that changes pitch/gets noisy when I press the gas pedal (key in position two). still on my way to get the fuel pressure gauge.
 

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Registered
2000 ML320
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182 Posts
Discussion Starter #11 (Edited)
alright- changed the fuel filter. thankfully it has the updated lines!

and still nothing, you can hear the pump humming but the buzzing sound is gone with the arrival of the new fuel filter.

poured gas into the intake and it purred along for a minute and then died, the engine revved when I pressed the gas with the gas in the intake- but eventually died.

(I started it for a while to get fuel through the filter and is exhibiting the same symptoms)
 

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Super Moderator
99 ML430, 00 ML320, 05 E500 4matic Wagon
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22,134 Posts
So the fuel pressure is at what level now?
You did the filter, but maybe the pump is on its way out.
 

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2000 ML320
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182 Posts
Discussion Starter #14
Fuel pressure is still at 10psi.

43sqd- my friends bright idea, I accepted his actions out of ignorance. I'm more of a hook up something that outputs information and figure out what's wrong kind of person, it'll never be an option again in the future.

If I keep doing what I'm doing, I'm just going to end up with a greater appreciation for those more mechanically inclined then myself.
 

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Registered
'00 ML 430
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235 Posts
With fuel pressure at 10 psi the engine won't run. If you trust that measurement your either have a bad fuel pump or poor power to the pump (assuming you repaced the fuel filter with a good new one).

To check fuel pump power you can replace the fuel pump fuse with an AMP meter. Reading should be somewhere around 4 - 5 Amp. Then, with the pump running (place jumper into fuel pump relay socket) also measure voltage at the fuel pump. Do the measurement right at the connector. It should be very close the battery voltage. Else maybe poor ground or harness issue. To get to the fuel pump is a bitch: You have to remove rear seat 2/3 seat bench, peel back the carpet and remove the cover that is glued in. There are PDF instructions out here - do a search.

If current draw and voltages are confirmed it it time to replace the fuel pump and confirm fuel pressure at the rail meets specification.
 

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'00 ML 430
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235 Posts
i tried it this morning, and the LED does blink once and no Start Error messages.

i did notice a buzzing sound in the engine bay, that changes pitch/gets noisy when I press the gas pedal (key in position two). still on my way to get the fuel pressure gauge.
the buzzing sound in the engine bay is from the stepper motor for the throtle plate. This is normal - it changes pitch as you depress the accelerator because the stepper motor opens the throttle plate.
 

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2005 SLK55 AMG
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253 Posts
Chris, replace the fuel pump.At 10lbs pressure it won't run.Mine had the same thing happen,it's a 1999.I notice yours is a 2000 and is probably due for a new pump. I bought a Bosch pump from autopartsway.ca , they offer free shipping over $75 in parts, since it appears you're in Canada. The new pump may cure any faulty fuel gauge readings that you might have.

If the link is not allowed a mod can remove it.
 

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Registered
2000 ML320
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182 Posts
Discussion Starter #18
thank you every for your help so far! the pump is on order, and i'll update you when I get some time to install it. while i'm waiting for the pump, i am going to test everything out and try to find an amp meter (my multimeter is some radioshack special) the pump is easy enough to return if it's not the issue.
 

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Registered
2005 SLK55 AMG
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253 Posts
Chris, it's very doubtful you'll be able to return the pump.Most parts place have a no return policy for electrical parts that have been used.

Also, if you're getting random misfires that too would fit into a faulty fuel pump.

Keep us up to date and good luck.
 

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Registered
2000 ML320
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182 Posts
Discussion Starter #20
sorry for the late check-in but i installed the new fuel pump and it was running smooth as butter!

then it stopped starting in the afternoon, which was after it was broken in to- but before my window switches broke (again)

she is in the shop today for diagnostics.

thanks for everyone's help, sadly she is getting on in age and it might be time to start car shopping.

I was so close to 300,000 KM too!
 
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