I recently bought a 240d and it's been doing fine. I had to replace both upper control arms and am doing other, minor, stuff to get it ready for winter. I think one, or more, of the glow plugs are shot. That's another issue. The problem I'm having is the car not getting fuel up to the injection pump. I've noticed, for several days, that the car would surge and lose power whenever I drove up an incline. When I attempted to start off for work the next day(Friday) the car got two blocks before stalling out. I noticed the primary filter had no fuel even though the car had about half a tank left. The car would not prime up with the lift pump so I towed the car home to take a look at it. I reversed blew through the hose to the tank before the primary filter and tried again. No go. I put my mity vac to it and, after getting the vacuum pumped up two thirds of the way, got diesel. But, when I released the vacuum, the fuel blew back into the tank! I did it again and left the pressure on and the vacuum stayed constant. I jacked up the rear and took off the hose from the tank and fuel flew out with no problems. Is the lift pump bad? Or do I need to get the whole unit as it doesn't pump up when trying to start either. It's probably a simple problem I'm not seeing but I'd like a more experienced opinion. Thanks!

You could try switching the feed and return lines under the hood to see if that solves the problem. It could be that the tank screen is plugged, although that would not account for why the fuel ran out at the tank unless the removed the return line and not the feed line.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I was wondering that too so I left the hose disconnected in the rear and tried to pump up a vacuum with no results so I did have the feed line. Another strange thing, when I was trying to prime the line I noticed the return line from the number one injector to the secondary pump was leaking. When I took it off fuel came out. More than I thought it would. I would think there would have to be fuel going in before the return lines would push fuel. I'm getting new return lines today! They're SHOT!!

When I first bought my 1979 240D, the fuel strainer in the tank was so clogged up with algae (looked like epoxy it was so thick) that I changed it out, removed the fuel tank and took it to a car wash to pressure wash it thoroughly (to remove any old crud that may have lurked there), then replaced with a new fuel strainer and fuel filters. those 240Ds need all the help they can get, in the power area!

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1983 300D (Hans)

Yep, startin with return lines oughta help. Through gravity injectors can loose their prime if return lines leak like seives. Also seen the same symptoms you describe when priming pump started leakin on my '79 240.

Meanwhile how's the fabric coated bits of fuel line underneath and up around fuel tank? Betcha they're needin replacement after 30 yrs. Insidious little bastards, MB fabric coated fuel lines hide leaks until you squeeze em and find em getting wet.

BTW, loop style glow plugs can easily be checked and diagnosed under visual inspect alone if ye dont know this already. Will be obvious if filament's busted or corroded to hell. Replace if lookin close to worn out is good maintenance practice. What ye wanna avoid is busted filament nubs falling into pre-comb chambers, not generally a major issue but something you wanna prevent.

And Thanks for starting an excellent thread with specific and searchable title that identifies model and year pointing to specific issues. Brian Carlton our moderator here and others are launching campaign against anybody who refuses to mention in thread title the version of diesel and subject being covered.

I vote for plugged tank vent. If you pulled a vacuum on it and upon releasing it the fuel sucked back to the tank there is no path for air into the tank. You may just want to try running it with the fuel cap off for a few to see how the filters look up front. OR you could try pulling a vacuum on it with the cap off and see if you get the same suckback. If you do then you need to check the strainer like the above posters suggest.

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2003 Dodge Ram 2500 Cummins - Georend fully built trans, Banks Big Hoss Bundle, Smarty Tuner, 5" turbo back exhaust. 500 HP and 1100 ft/lbs to the ground.
1979 Mercedes-Benz 300CD - Lost to a four car pile up on 275, Thank You Michigan Drivers.
1986 Mercedes-Benz 300D - Sold, Euro non-turbo car.

Yep, all of these items oughta be considered contributing factors.

And here's another thought: when ye replace the secondary filter do ye line up 22mm banjo bolt so it feeds straight into injector pump feed line? Mine gets smacked with chisel to permanently mark exact position of banjo hole i wanna line up to achieve direct flow.

Wow! Great ideas!! The return lines are super shot. I'm sure that's part of the problem. I have replaced the secondary filter too so I'll check on the banjo bolt. When I bought the car, in California, I filled up with bio diesel. I thought it was cool at the time but now, since I've learned how bio diesel eats on plain rubber lines, especially old ones, I'm not so sure there isn't a collapsing fuel line somewhere. I check it out tomorrow as I have no time today. To many other "hot" fires to put out! Thanks again for the great advice!

I got my fuel issue fixed. The car came with an extra tank in the trunk. I took it out(it must have a 30 gallon capacity!!!). I plugged the 1" ID hose that ran between the tanks and then plugged the small hose off the other end. I didn't check to see where the small hose went as the car started and ran fine. I filled up and the car drove fine until the tank was almost half full when the car acted like it was starving for fuel. One day, it died a couple of blocks from home and wouldn't prime up with the primer pump. I finally followed the hoses and discovered the small hose I had plugged was the feed line. How did the car even get fuel to run a half a tank? The pump must have, somehow, drawn fuel from the return. Or that's the only thing I can think of. I reduced the large hose, so I could get the feed hose hitched up to it, and the car primed very easily and I had plenty of fuel. I feel kind of bad about not following the small hose, when I took the extra tank out. It runs a lot better now and have more "power" than I had before, which makes sense. I'm really glad the car's running good again as I really missed the car. The 240d's aren't fast, but they sure grow on you!