[nightheron]

Hello. After running faithfully for several years, my 280E (Vin# 123 033 12 058xxx, relatively low mileage Euro, or "grey market" car) has died in our driveway, with a full tank of gas, I might add. When I started it up it slowly starved of gas, while never fully springing to life, and that was that.

I believe the fuel pump is dead, or the fuel filter is finally clogged (I have often bought gasoline at the place I did the last fill up, so I am not blaming the gas). I did check the distributor cap and rotor and the hot central spring-loaded hot connector had popped off and got lost on the ground. Fortunately I had an old (similar) cap that I used in its placed (for now). It bothers me that I could not see signs of life when I added a small amount of gasoline into the carburetor and cranked the engine, but with no indication of life. So it is possible I have electrical problems other than the fuel pump.

So, I am going to attack the problem on a couple of fronts. Firstly, I am getting new replacement distributor cap and rotor parts. Secondly, I am getting a new fuel pump + filter. I managed to get a fair price on a new pump which I plan to install as a matter of maintenance in a few months, even if I find I don't necessarily need it right now.

My one worry is what problems am I likely to encounter when attempting to remove the fuel pump (+ filter) that I should be prepared for (like rust/stuck fittings)? The car is stuck in the driveway, and I will be only able to jack up the rear part to climb under it. I have fair weekend mechanical skills, but am far from being an expert. One thing that bothers me is the fuel pump relay; I intend to buy a replacement for this only if everything else fails, although I may try to do some resistance/shorts tests on it.

Thanks for reading the post.
NH

 

[Nutz 4 Benz]

Have someone crank the engine with the distributor cap off while you look at it to see if it rotates to verify that the timing chain has not snapped.

280E and carb It still should have sputted when you dumped gas into it. Is the coil good? Is the coil wire fried inside? Do a resistance test on it.Fuel pump relay dead?

 

[flyboyike]

Check to see if there is voltage at the fuel pump.

 

[nightheron]

Thanks for the replies. Rotation seems to be fine with the cap (and rotor) off when cranking. Also, the resistance of the coild wire seems fine.

I can't locate the fuel pump relay. All I have found so far is a 5-pole relay (0015420219) over the left front fender, and two other relays bound together over the right fender. Where is the likely location of this? I understand it is supposed to be a 6-pole type.

I did not have a chance yet to check the voltage at the fuel pump.

Regards,
NH

 

[flyboyike]

Thanks for the replies. Rotation seems to be fine with the cap (and rotor) off when cranking. Also, the resistance of the coild wire seems fine.

I can't locate the fuel pump relay. All I have found so far is a 5-pole relay (0015420219) over the left front fender, and two other relays bound together over the right fender. Where is the likely location of this? I understand it is supposed to be a 6-pole type.

I did not have a chance yet to check the voltage at the fuel pump.

Regards,
NH

Do you have 5 relays in a box on the left fender? The fuel pump one is the rearmost inner one.

 

[nightheron]

Yes I do have a relay box on the left fender (with room for about 5 or 6 relays if I recall), but there is only the one 5-pole relay that I mentioned in it. When I get home from work this evening, I will scout around some more.

 

[Nutz 4 Benz]

That's the one. You must have a no option W123 huh?

 

[nightheron]

This car came from Germany in the mid-80s'. I guess it is lean on options (fewer things to fail I suppose) It confuses me that I apparently have a 5-pole fuel pump relay rather than a 6-pole one. All the parts supply vendors I checked recommend a 6-pole one for this car (although it being a Euro car may confuse the issue).

Thanks for the help.

 

[FratBoy]

I spent hours looking for a fuel pump relay on my 1980 Euro 280E that was originally sold in Germany. There isin't one. The fuel pump is on in run and start. The best way to test this is right at the pump. Disconnect the pump wires and attach the volt meter.

I was able to pinpoint the fuel pump as my starting problem in two ways: the pump didn't run- ever (you should hear a fuctioning pump if you kneel down under the right rear of the car), and I was able to get the car to light off by spraying Thrust starter fluid into the intake manifold.

Replacing the fuel pump and filter is easy. It is all one unit, and comes off with simple tools. The most difficult part will be clamping the fuel line from the tank so you don'tmake a huge mess...

FB

 

[ducatipaso]

The most difficult part will be clamping the fuel line from the tank so you don'tmake a huge mess...

and you know this how?

 

[FratBoy]

and you know this how?

Lets just say I made a little mess in a JY. I thought for sure they drained those tanks before putting the cars in the yard.

As for mine, I siphoned about 12 gallons out through the opening for the fuel guage sending unit. After removing the first aid kit box and sending unit, you can put a gas tank in the trunk and pump right into it without getting fuel in your cab. Be aware, there will be gas left in the sending unit as you pull it out. It has very small drain holes.

FB

 

[ducatipaso]

you mean there's no drainplug?

 

[FratBoy]

you mean there's no drainplug?

I didn't look for or find one...

FB

 

[nightheron]

Hello again. Thanks for the helpful responses. I changed the fuel pump (using an OEM type) and fuel filter (obtained from Mercedes). I am now getting some fuel to the engine but not enough to completely start the engine and keep it running.

Obviouly I have residual air in the system. I probably should have filled the fuel filter with fuel before hand and so on and so on, but due to the extremely cold weather we have in the Northeast USA right now and being sick of inhaling gasoline fumes, I tried to cut some corners.

Any suggestions, short of climbing under the car again and loosening connections, for getting the air out?

Thanks again
NH

 

[Nutz 4 Benz]

It will purge itself,no need to suck on hoses as it is not carbed. Is the cold start injector spraying and thermo-time switch working? Fuel injection pressure gauge handy? Here,check this write up out and read only the K Jet

http://www.benzworld.org/forums/w116-s-se-sel-sd-class/1223523-bosch-d-jetronic-k-jetronic-troubleshooting.html

 

[nightheron]

Hi Nutz. Thanks for replying. Actually it does have a carburettor rather than a fuel injector system ... seems like there were so many variations of options in these old mercs ...

 

[Nutz 4 Benz]

Well,in the first post it says that you have a 280E which is a fuel injected model.
You have a 280 then with the M115 carbed engine,hmmmmm,back to the drawing board.Let me regroup



Edit,does it have a Stromburg or Solex carb?

 

[nightheron]

Hi. I have always understood it to be a 280E, as did the previous owner, Mercedes parts places, and so on.

I checked the markings on the carb cover and found stuff like "MANN 45 120 85 686" and "Patrone C32126", though those could be cover related.

At the moment I can get the engine to continue running, but only when I keep my foot on the accelerator. Also, there are frequent "explosions" coming from the exhaust pipe, and the carb insides have become lightly coated with carbon.

 

[Nutz 4 Benz]

Can you post a pic of the engine?

 

[nightheron]

Here goes, I hope this works. Sorry the picture s not that sharp.