This obviously something that may be anywhere, but I thought someone might have a clue where the most likely place for a minor leak might be.

We got this car about 6 months ago. It has 90,000 miles.
I noticed a fuel smell recently, but didn't notice a leak.
The other morning I noticed a fuel trail down the road, but still no visible leak.
Tonight we visited some friends who live on a steep hill.
PArked the car uphill.
When we got back about 3 hours later car wouldn't start.

After a few turns I coasted the car so it was pointing down hill.

After killing the battery I pulled the filter and found that there was about 3/4 inch of air in it. Filled it with ATF and the car started.

So, I think what happened was gravity sucked air into the system.
Anyone have a clue where a slight leak might be?
Secondary filter maybe?
Where is that sucker? (pun intended)

Rubber fuel lines. Supply and return. Have you checked them end to end?

I just pulled the ones on my 95 e300. A was noticing fuel smell and a wetness down the drivers side of the block. Looking closely where the supply line comes into the fuel heat exchanger, the line was shot under the hose clamp. Could see air in the hard plastic lines while the engine was running. Once I replaced them with 5/16 line, no smell, no leak, no air. Better throttle response and so far it seems better mileage

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'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

Quick answer:
The two lines look almost new and are translucent. I can see the fuel in the lines and there are no air bubbles that I can see.
The lines are not leaking or cracked.

Long answer continued:
I bought this car about 6 months ago.


I had the mechanic who did the inspection perform a "diesel purge" injector cleaning, actually before I even drove the car.
I'm not sure if he actually did it, but he put the empty can in the trunk and charged me for it.
It had and still has good power.

This car has 90,000 miles on it and I bought it off ebay in Florida (there is a first and last time for everything)
I had a reputable mercedes mechanic look at it and he gave it a thumbs up.
It took me a while to realize it, well I realized some things immediately, but the car looks like it was driven by a little old lady, then sat a while and was snatched up by a used car dealer who spit-shined it.
I suspect the mechanic knew the seller and didn't go over the car with a fine tooth comb and didn't mention some things that I did immediately.
For the price I paid it would still be a good deal after I spend the $1000 on the body: needs rear bumber lower valance, rocker trim missing, one rear trunk well is cut away??(rust?) there is spot rust on the rocker trim mount holes, headlights need polished or replaced, one fog light is missing.
I know it sounds rough, but basically it looks like it was painted and someone forgot to put some trim back on.

I think you're looking at the wrong lines. The hard fuel lines have their own issues.

I'm talking about the two rubber lines that connect the engine fuel system to the hard lines that go back to the tank.

One should tie into the fuel heat exchanger, just under the first 1-2 intake manifold runners. The other line should come off a port on he secondary fuel filter housing and return to the hard lines.

Factory rubber hoses have nice little bends in them and may be sleeved in a plastic/rubber tube in the mid-section of these lines.

From the dealer, these rubber hoses are upwards of $175, but 5/16" line seems to be working just fine for me. And at $6, a much more viable resolution to my fuel leak problem.

__________________
'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

On the plastic lines, the translucent ones, it's not the lines themselves which leak, it's the O rings on the ends. The lines can look fine but the O rings may be leaking. The prefilter O ring is another source of air leaks. Finally if all else fails the lift pump could be bad.

Rgds,
Chris W.
'95 E300D, 406K

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Objects in closer are mirror than they appear.

Here are the most common leak areas...

http://www.peachparts.com/shopforum/mercedes-parts-reference-library/193833-om606-912-1996-97-e300-diesel-plastic-injection-pump-lines.html

http://www.peachparts.com/shopforum/general-information/173991-om60_series-ip-delivery-valve-reseal.html

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The delivery seals and clear line orings are fairly easy to see.

Given that OP says he can't see the leak clearly, I'm assuming it's where the rubber line ties into the heat exchanger. Very hard to see under the IM and if it's leaking, it seems to trickle down the driver's side of the block.

My PO had changed all orings and delivery seals, so I can't say that I have firsthand knowledge of those leaks. But I know the rubber lines took me a while to realize and not much time to replace...

__________________
'85 300TD "Puff The Magic Wagon" - Rolling Resto
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter

I need my little angle mirror.
I need to take the car over to the industrial area and park one wheel on a hump to get a good look under there.

Thanks guys.