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2007 ML320 CDI
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Discussion Starter #1
This is making me crazy. 2007 ML320 CDI wont start when Hot. will start and run just fine after a 30-40 minute cool down. Already changed the crankshaft position sensor. No Help. I have read about the low pressure fuel pump being at fault. Can anyone give some advise on this ?

Scott
 

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This is making me crazy. 2007 ML320 CDI wont start when Hot. will start and run just fine after a 30-40 minute cool down. Already changed the crankshaft position sensor. No Help. I have read about the low pressure fuel pump being at fault. Can anyone give some advise on this ?

Scott
Perhaps a bad booster pump in the fuel tank, or could be a loose fuel line , maybe at the filter, causing air problems.
 

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2007 ML CDI, 1967 250SL(early), 1984 280 SL, 2004 E320 wagon, 2015 ML 250, 1999 E300TD
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449 Posts
Does a check engine light come on when it doesn't start ?
It sounds like the old vapor lock problem on the old MB's.
Any fuel smell ?
Any funny sounds during non start cranking?
does glow plug light go on and off as usual?
engine idles smoothly?
when you cool down does it start instantly on half a crank?
let us know
 

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2007 ML320 CDI
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Discussion Starter #4
No check engine light ever
no fuel smell
no unusual sounds at all
glow plugs go on and off right away as the engine is still hot
runs perfectly after restart
starts right up but maybe 3 cranks.

My money is on the low pressure pump. 2nd choice is the high pressure pump.

will check it again today after a trip

Thanks
 

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No check engine light ever
no fuel smell
no unusual sounds at all
glow plugs go on and off right away as the engine is still hot
runs perfectly after restart
starts right up but maybe 3 cranks.

My money is on the low pressure pump. 2nd choice is the high pressure pump.

will check it again today after a trip

Thanks
Lets hope its not the high pressure pump as that is Expensive!..also ..has your fuel filter been changed recently?
 

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2007 ML CDI, 1967 250SL(early), 1984 280 SL, 2004 E320 wagon, 2015 ML 250, 1999 E300TD
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449 Posts
Good point Vern.
How many miles on the beast ?
I can't think what causes the warm engine restart problem?
If it is a fuel blockage or air leak (which it sounds like), what does the engine temp have to do with it ?
Is some sensor getting overheated and causing the hot no start ?
Can it be electrical?
 

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2007 ML CDI, 1967 250SL(early), 1984 280 SL, 2004 E320 wagon, 2015 ML 250, 1999 E300TD
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449 Posts
I forgot to comment- my CDI starts on a half crank, always.
Has the 3 crank start always been the case?
Maybe faulty glow plug relay is causing problem.
But any electrical malfunction would show up with a CE light.
 

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2007 ML320 CDI
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Discussion Starter #8
70,000 miles on it. I have a fuel filter on order. its got some fancy clip clamps securing the fuel lines. I may just use worm clamps. I have it scheduled to go to the dealer on Monday. Scares the @#$% out of me. They treat people so poorly. if it wasnt under warranty I wouldnt go but parts are to pricey to throw around. It usually fires on 2 or 3 turns. maybe the low pressure pump is part of that too. I can hear it power up but I cant tell if it sounds right or not. I am not thinking about glow plugs yet because it should be hot enough to fire without them. The light is only on for a split second anyway. Is that normal ? last car was a 98 E300. That was old school.
 

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2007 ML CDI, 1967 250SL(early), 1984 280 SL, 2004 E320 wagon, 2015 ML 250, 1999 E300TD
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My son has my 99 300TD now and it still drives and runs like a dream.
So it is still under a stark mark warranty?
Then take it to dealer, by all means and drive that C300 loaner.
2 weeks ago I left my CDI out for 3 days in 0 deg temps.
The fuel gelled and it ran for 60 seconds then stalled, unable to pull fuel into the IP.
Luckily it warmed up the next day and all was fine, but a CE light came on to tell me that the fuel pressue at rail injector was low.
So, I can't figure why yours didn't throw up a CE light?
 

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70,000 miles on it. I have a fuel filter on order. its got some fancy clip clamps securing the fuel lines. I may just use worm clamps. I have it scheduled to go to the dealer on Monday. Scares the @#$% out of me. They treat people so poorly. if it wasnt under warranty I wouldnt go but parts are to pricey to throw around. It usually fires on 2 or 3 turns. maybe the low pressure pump is part of that too. I can hear it power up but I cant tell if it sounds right or not. I am not thinking about glow plugs yet because it should be hot enough to fire without them. The light is only on for a split second anyway. Is that normal ? last car was a 98 E300. That was old school.
Do you know how many fuel filters it has had over the yrs? You should be halfway through the third one.I noticed that the dealer replaced the ''click'' clamps on mine with regular hose clamps last time, so its ''do-able'' that way.
 

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2007 ML320 CDI
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Discussion Starter #11
I bought it used from the dealer last April. the warranty runs out this April so I will bring it in on Monday and have it looked at. The bad part is that now I cant duplicate it. I really believe its a low pressure pump or the control relay to it. It could be something in the filter. I want them to change something at this visit so I can at least start ruling things out.

I loved my 98 E300. I needed a 4 matic for the New Jersey winters. I wish you could get the E320 in a 4 Matic.
 

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2007 ML320 CDI
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Discussion Starter #12
I read an old post where one of the members here had an R320 with the same problem. I sent him a PM and he told me he hasn't had any problems since they changed the low pressure pump and his never threw a code either. so I am going to push hard for a pump on Monday
 

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Discussion Starter #13
Well... the problem went into remission 3 days prior to my dealer visit so the dealer wont do anything except change the fuel filter. I understand the desire to change the filter but I dont think that would cause this problem. I told them I have a filter coming to me Wednesday and I could do it for 30 bucks not 200 bucks like they want to charge me. They offered to drive the truck for a few days but they are not going to get fuel filter out of there heads until its changed. So I will take it back, change the filter and wait until it fails again. They make me crazy. I gave them a bunch of data on the problem and they wouldnt even read it. My warranty runs out in April so I hope to resolve it by then.
 

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Does a check engine light come on when it doesn't start ?
It sounds like the old vapor lock problem on the old MB's.
Any fuel smell ?
Any funny sounds during non start cranking?
does glow plug light go on and off as usual?
engine idles smoothly?
when you cool down does it start instantly on half a crank?
let us know
@zak.
Mine is having exactly this issue as you stated. I changed all the injectors few months ago and the hard starting stopped but came back after two month.
 
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