This had occasionally happened before but yesterday it happened 4 or 5 times! The engine would just die all of a sudden and I couldn't restart it while rolling even though I put the transmission in neutral. I had to pull over each time, put in park and then the engine would restart, but not always on the first try. When it didn't want to restart the red and green lights on the rear-view mirror were flashing, indicating some kind of problem.

My first thought was the electrical connection to the shutoff pump which I'm going to inspect and clean tonight. I replaced the shutoff pump last year because the old one was leaking. I will also check for air bubbles in the plastic fuel lines, but I don't think that's the problem because I replaced all the o-rings last year too. Any other ideas or items to check? I hope it's just a simple electrical issue if there is such a thing. It doesn't feel like a mechanical issue.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

It does sound like its fuel starved and or loosing prime.......have you checked the inline fuel filter and "o" ring for clog or leaks.....and changed out the Main Fuel Filter? Also check to make sure your fuel cap is tight and not cracked or broken....

Good Luck!

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FRED

Daily Driver: 98 E300TD 199K
Hobby Car: 69 Austin Mini
Past Diesels: 84 300SD, 312K
87 300SDL, 251K
94 Chev. K-1500 6.5Ltr.TD, 373K

Yeah I've thought of the fuel filter, but I think if the filter was clogged the engine wouldn't just quit on the highway without any warning. I think I would first experience power loss and maybe rough idle, but that's not the case. The fuel cap looked fine the last time I saw it.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Same sort of thing happened to me recently and it turned out to be the O-ring on the prefilter. Since the system primes while you are cranking it, this would explain the intermittent run-then-die behavior.

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Scott C.

2006 E320 CDI (120k miles)
FOR SALE: 1998 E300 Turbo Diesel - Black w/Tan Leather - Euro delivery (236k miles)

Although the following info from "ALL DATA" is for a '95 E300D, Perhaps its applicable to you too

There is a Mercedes Technical Bulletin that describes the EXACT same symptoms that you describe. They attribute this to a faulty Over Voltage Protection Relay [OVP], specifically an internal Solder Joint Fault. A Computer fault code may or may not have been stored.

It seems that there was a batch of defective OVP relays. Also, did you by any chance change your OVP relay in the past for a used one?

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Scott, when I was replacing the fuel shutoff pump last year I also had the prefilter out and it was clean and the o-ring looked new so I don't think that's the problem.

pberku, you may be onto something here. I've never touched my OVP relay and I don't even know where it is or what it looks like. I just did a search in the parts catalog and didn't see it there either. Do you know where it is or what it looks like?

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Oops. now I am not sure that the 96 E300D's had an OVP. Maybe someone can chime in and advise

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Well if your car has it, maybe you can point me to the right location so I can take a look and see if I have it. We do have the same engine after all.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

In my car, its behind the Battery. There are several relays there, One of them is the OVP. The OVP housing is silver and has a 10A fuse on top.

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'95 E300 Diesel, 264,000 Miles. [Sold it]

Spoke w/ someone about this and they stated it's the K40 relay, where the computers are - apparently it's for all of the w210's... It's like a $75 part from what I heard

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#dieselFLEET
---------------
'97 E300
'99 E300

So I cleaned the fuel shutoff connection and even took apart and cleaned the intake air temperature sensor for good measure. Then I had a look inside the "computer box" which sits where the battery would normally be in another car and I took the attached picture. I saw a K1 relay there, but not a K40. There is a piece of hardware that has 3 fuses on it, including a 10 amp one but the housing isn't silver. I'm going to drive the car again tomorrow and see how it goes. In the meantime, what are your thoughts on which piece of hardware is the suspect?

Attached Thumbnails

 

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

The box with the three fuses on it is the K40 relay - I'm new to the W210 world and I'm still learning the new web-based ETM diagrams but it appears the K40 relay is responsible for providing power to run the IFI (fuel management) functions on your car.

If I'm reading the diagram correctly the power for the IDI system is obtained before the 10 amp fuse comes into play so it would appear the K40 relay is providing power and overvoltage protection but the 10 amp fuse is not protecting the IDI system from excessive current draw. Very strange.

I don't know if the K40 relay is your problem but if the relay dropped power to your IDI system I'm pretty sure the car would at least stumble and maybe shut-down totally.

Do you think it's possible for a clogged fuel filter to cause this problem? Last time I dismissed it because I was thinking of a purely mechanical diesel engine. But now I'm wondering if in this case it's possible that a clogged fuel filter might put enough strain on the lift pump (which I believe is the same as the shutoff pump) to cause an overload on the electrical circuit. I did change the filter less than a year ago, but since then I've run a bunch of additives through the tank, including StarTron, so I can't be sure that the filter is still fully operational. I drove the car this morning after filling up with fuel and it didn't die on me this time. If the filter is the problem, I'm sure a full tank of fuel would help alleviate it.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL

Another possibility is that you have a fuel leak (with the resultant air ingestion) that only manifests itself when you have less than a full tank of Fuel (I did).

Observe if the symptoms occur only when the tank is less than full.

Phil

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'95 E300 Diesel, 264,000 Miles. [Sold it]

I believe I have already fixed all the fuel leaks except maybe the #6 injector line which was leaking at the injector the last time I checked it but I retightened it and it should be fine now. Even if it's not, I don't think it could be responsible for these symptoms. At this point I have two suspects: the main fuel filter (hopefully not the screen in the tank) and the K40 relay. I'll keep you updated on what I find.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL