Second post here...this site looks pretty cool.

If this has been covered before...please accept my appologies...I've searched some but with no luck...and I'm in a pickle.

My 1981 300SD worked fine in the morning...then in the afternoon....on the way to pick kids up from school....it slowly lost power, like it was starving for fuel. Had to depress the pedal farther and farther....

Then it died. Managed to start and get to curb. Now it won't start..(towed it home) and I think it sounds like a fuel pump problem...but I'm no mechanic and diesels I'm totally a noob.

I did replace a little clear filter and another that looks like a small oil filter...no help. I disconnected the fuel line before the little clear filter (located by engine block driver side) and with ignition on...no fuel comes out. Reconnected and then seperated after filter up by larger fuel filter (looks like a small oil filter) and some fuel will "pulse out" with the engine cranking....but it doesn't seem like alot.

I bought a chilton manual, but the information is schetchy at best...I tried to find the fuel pump underneath the car where the book suggested, but alas...I don't see it.

Can any one help with the location of it? Troubleshooting tips?

Can I get the pump off the car easily? Is it likely the problem?

The car has over 200,000 miles on it so perhaps its time for an new pump.

Appreciate any help.

If you take off the fuel line before the clear plastic pre-filter, as you described doing - fuel should run out. That section of fuel line should freely drain the tank, because it is lower than the tank itself. (The tank being directly behind the back seat.)

This tends to limit your likely repairs, because you have taken a good logical approach to dividing and conquering the problem.

The most likely items involved are the fuel strainer or the fuel tank vent. Eliminating the fuel tank vent is easy - just take off the filler cap. If you hear a whooosh of air rushing in, you probably have an issue with the tank vent. If you still get no fuel flow after removing the filler cap, the next most likely problem is the fuel strainer in the tank.

I think you can search on these two items for more information, but by all means if you have any more questions just ask - and tell us your results.

Ken300D

__________________
--------------------------
1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

The clear filter shows full in it 3/4 full....after the engine is cranked...but yeah...when i split the line before the filter...nothing comes out. When I remove the cap...I can hear a little air sucked in....that is bad?

A little bit is not a problem. A giant whoosh is bad.

The key is to check again if fuel will properly drain from the tank once the filler cap is off - if not, you likely have a blocked fuel strainer. The typical reason for strainer blockage is fungus/algae.

You can search on algae here and get a lot of information. The key is maintaining a water reduction & elimination strategy, most easily done with a fuel additive like Power Service. And keeping the tank nearly full in really cold weather.

Ken300D

__________________
--------------------------
1982 300D at 351K miles
1984 300SD at 217K miles
1987 300D at 370K miles

Ahhhhhhhhh....okay....I didn't check fuel line with the cap off. I'll try that...

Hmmm...yeah...we just went thru a very cold spell last week....in fact when this problem happened it was in the 18 degree range outside....and I only had about 1/4 tank of fuel.

You don't suppose my fuel is water soaked? Condensation? Any good way to drain the tank and remove the water...I hear its behind the passanger the back seat somehow...

The way I read it you didn't use the hand primer at all after replacing the filters? Make sure both filters are on correctly then just barley loosen the top bolt holding on the large fuel filter (the one that looks like an oil filter) then unscrew the hand pump (Driver's side of the engine compartment) and pump away until fuel starts to come out the top bolt. Tighten bolt and your done. Try to crank it over now.

__________________
'85 300SD (formerly california emissions)
'08 Chevy Tahoe
'93 Ducati 900 SS
'79 Kawasaki KZ 650
'86 Kawasaki KX 250
'88 Kawasaki KDX200
'71 Hodaka Ace 100
'72 Triumph T100R

Your right..I didn't use the pump at all...until i was reading in the Haynes manual about it....I didn't know the pump existed till a few minutes ago....they said to do it until I heard a hiss...but I didn't loosen anything...I'll try again and look for fuel.

Do you always have to loosen that bolt? I ran out of fuel once, (in a bad part of town), and when I finally was able to put more in I just pumped till it was harder and I could hear the fuel going out the injectors? I ran out after a sharp turn so maybe there wasn't really any air in the lines?
Thanks
Davd

__________________
_____________________________________________

2000 Honda Accord V6 137k miles

1972 300SEL 4.5 98k miles

_____________________________________________

Duelten

The Haynes manual is much better than Chilton and would be worth your time and $ to pick one up. The CDs are available on e Bay also. the secondary fuel filter (bigger one) can be filled with fuel before you install it and will save allot of pumping. I carry a qt of fuel in the trunk for emergency use. The primary filter will have air in it, thats normal and fuel will not "gush" out the supply line. Be sure your battery is good and charged as it needs to crank over the engine at 100 rpm. Whens the last time the valves were adjusted? You probably got her running by now anyway.

__________________


1985 Euro 240D 5 spd 140K
1979 240D 5 spd, 40K on engine rebuild
1994 Dodge/Cummins, 5 spd, 121K
1964 Allice Chalmers D15 tractor
2014 Kubota L3800 tractor
1964 VW bug

"Lifes too short to drive a boring car"

I did that and OMG!!!!

It fired up! It actually started!

What should I do now? Should I add some additive in the gas tank to help clean the tank/fuel?

I'm not a weirdo...I'm happily married, but doggone it you have made may day...heck..you've made my year (its been a rough year with family members dieing and a new move)....I could just hug ya!

Your cheapest and best move right now.. while you are motivated.. is to use the search and read all you can about these items...
Then you might just wander through the current pages at the bottom of the diesel forum page and read titles which sound interesting...

Be aware of the fact that your diesel does not have an electric fuel pump like the gasoline engines do. It is a mechanical fuel injector pump, with individual high-pressure plungers for each cylinder. I doubt that you need a new pump.

With 18°F weather, your fuel may have started gelling. Try an anti-gel additive in future cold weather to prevent this from happening. Also you may need to clean the pick-up screen in the tank. Search for fuel pick-up screen, as this topic has been covered before.

Good luck!

You bet fellas! I'll be browseing and searching these forums for tips and such related to this issue and the better care for my car.

I am a fairly new Mercedes owner...this is my first mercedes and I've only had her since november....but I can see I need to learn some things and do some maintaining....

She is running now and I have ran down and bought some additive and added it to a brand new tank of fuel.

Thanks again everyone. I am so very happy to have found this site!

P.S.

Just wanted to mention.....I bought both the chilton and the haynes manuals....gotta say...I'm kinda disappointed in both. The chilton, while it's electrical section was better, claims that my car has an electrical fuel pump ( i of course, couldn't find it) and the haynes, while having better pictures, will not go into any detail by saying "its tooo complicated so you should take car to a MB dealer or approved shop" ....

Neither one had very good troubleshooting sections to speak of....this site blew both of them away. Heck...kinda makes me want my money back from the books so I can send a donation here....

In fact...if any mod or admin would contact me...I would be very happy to make a donation here...I believe I will spend much time here to learn about my car and would like to help assure that the ppl running can keep it up.


Thanks everyone.

amlessig@hotmail.com

I suffered from a blocked strainer and "ground to a halt" on a couple of occasions until I correctly diagnosed the problem.
I reversed the connections from the fuel suction line and ruel return line and over came the blockage completely.
I bought some $2.00 clear in-line filters and change them as they block.
I am about to re-connect the lines to normal, as I feel that all of the "crud" has been deposited into the cheap in-line filters by now.
The key to this process, is to run the tank very low (keep a couple of litres of diesel in the car) and be prepared to stop, to either replace the filter, or add fuel.
It is easy to tell which is needed, the clogged filter always appears full, the empty tank shows with the in-line filter about 1/2 empty.

__________________
Tony from West Oz.
Fatmobile 3 84 300D 295kkm Silver grey/Blue int. 2 tank WVO - Recipient of TurboDesel engine.
Josephine '82 300D 390kkm White/Palamino int.
Elizabeth '81 280E, sporting a '79 300D engine.
Lucille '87 W124 300D non-turbo 6 cylinder OM603, Pearl Grey with light grey interior


Various parts cars including 280E, 230C & 300D in various states of disassembly.