my 1997 300D has a hard time starting after it sits 2 days or more. i have to keep the starter turning to get it to fire. it will finally pick up all cylinders and then it's fine. it gradually seems to pick them up. after i get it running it runs great. it starts every time till i let it set for 2 days or more. is this a fuel pump problem?
138k

How's the glow plugs? It sounds you might not be getting enough glow and then end up starting the engine on compression alone.

I have a 1999 E300. If yours is electrically the same as mine and your glow plug light goes off after the engine starts I am guessing that it is not the glow plugs. There is another possibility which is a fuel leak that I just fixed. The leak was very minor and took a couple of days until it was large enough to drip on the floor, however, that little leak made it very difficult to start. The leak was in the o-ring seal for the fuel shut-off. When I realized it was a leak I thought that it was the hose that connects to the bottom of the fuel shut-off, but after replacing all of the hoses I still hade the same problem. Your leak might be even small than mine, but it still can cause great grief.

Check the following:
1. Open the hood....do you smell diesel? This was the really tricky part for me because I had just filled the car with petroleum diesel after running B100 all summer. If you smell fuel go to #2. If not I am not sure.

2. Drop the belly pan and see if it has diesel fuel on it. If is It so I am guessing you have a leak at the shut-off and go to #3

3. From underneath look up at the bottom side hose connection to the shut-off. If it is wet then the seal at the head is probably leaking. This is what happened to me. The fuel was dripping from the hose connection, but it was starting between the shut-off and the head at the seal.

The seal at the shut-off is an o-ring 17mm OD, 12mm ID, and 2.5mm thick.

The seals at all of the hose connections are o-rings 13mm OD, 8mm ID, and 2.5mm thick.

If you have fuel leaking replace of these seals for peace of mind. You may have to replace some the hoses (they come with o-ring seals) as I had to break the snaps on one of the hose connections to get it open enough to disconnect it.

I had quite a time and have a fairly long post for mine at:
Starting issue - 1999 W210 E300

Let me know what you find.

PS What part of Michigan are you at? Perhaps I might be able to make a road trip this weekend to help.

Where are you?
You can PM your location to me.
I may be able to help, Detroit - metro area is where I live.

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