1978 Mercedes 280SE - PeachParts Mercedes-Benz Forum

78280SE · #1 04-02-2009, 12:19 PM

Hello,
I just purchased a 78 Mercedes 280SE, Apparently the only problem with the car is either the fuel injectors, fuel distributor, or both. I searched and have found a couple of distributors online. Quite expensive, but if that is all this car needs than it's a great deal because I only paid $200 for the car. And the body, interior, electronics, A/C, and just about everything else is in immaculate condition.

The guy I bought it from seemed pretty straight forward and honest, he told me the car ran great until last June when the fuel injectors started flooding the cylinders. He said he had to siphon the fuel out and that I will have to drain the crank case as well.

He said it could be the o-rings on the injectors as well. Something about the ethanol in newer fuels makes the original o-rings brittle.

He also mentioned he has had two mechanics give up on it, which makes it hard to believe it is only the o-rings. He said he had a lot of trouble finding the parts and that he came across a great deal on another Mercedes so he just put it in storage and said the hell with it.

I am not new to auto mechanics but this is my first Mercedes. So I am completely lost.

My questions are:
Do the fuel injectors and fuel distributor come as one piece? The distributors I have found online look like they already have the six injectors screwed in.
Would the Fuel injectors/distributor be the only cause of fuel filling up the cylinders?
If I buy the distributor and injectors, could it be as simple as draining any left over fuel from the engine and putting the new parts in? I doubt it.

Where would would you start if this were your problem?

FYI- The guy I bought it from said he drained most of it out and put something in the motor to preserve it while is sat.

The engine turns over but won't fire of course.

Any help would be greatly appreciated.

Robert

porkface · #2 04-02-2009, 07:40 PM

just because the po had 2 mechanics give up on it, doesn't mean a mercedes tech couldn't. if you've not done kjet-the bosch design system on that car- before, i suggest you find a shop. i'll bet someone screwed up more than be seen on the net. otherwise, it's time to buy tools you don't have and go for it. type kjet into google and see what you can learn. good luck, chuck.

78280SE · #3 04-03-2009, 12:46 PM

Thanks Chuck, I will give that a try.

ja17 · #4 04-03-2009, 06:28 PM

Hello,

These fuel dstributors are dirt cheap used at your local Pick and Pull. Keep on the look out for one. Someone told me once, that a bad electric fuel pump can also cause a full rich problem? Not sure about this but he explained that the fuel pressure from the electric fuel pump controls the mechanism in the fuel distributor which regulates fuel mixture.

Anyway it sounds like you got a great deal. If you need someone to take this headache off your hands let me know

280EZRider · #5 04-03-2009, 11:37 PM

Here you are: 1984 280 e ce complete bosch k fuel injection

78280SE · #6 04-06-2009, 11:31 AM

When you spoke about the bad electric fuel pump causing a fuel rich problem. Could that be the cause of the engine filling up with fuel. I mean, there is so much fuel pouring into the motor that when you check the oil dip stick it smells more like gas than anything else. I understand a fuel rich problem, but could a malfunctioning pump be throwing the pressure off in the distributor causing this massive amount of flooding? He did show me the location of the fuel pump near the gas tank and said that it may have something to do with it.

So maybe I should just go ahead and replace the distributor and the pump just to be sure. I have found the pumps online pretty cheap. And another reply on this thread gave me a link that has someone selling the entire Bosch Kjet system including the injectors. I don't really want to have to replace the whole thing. But then again, I don;t want to just keep throwing parts at it until it fires up. If I could get an entire system that works it may be worth. More money, but less time trying different parts.

But then again, I don't really think it's the whole system. I have been told be several people that the fuel distributor is one of the most common parts to go out on these cars. A little over engineering on Mercedes' part I think.

Any thoughts on that? Would you just replace the whole system if you had the opportunity or just try the fuel pump and distributor?

Quote:

Originally Posted by ja17

Hello,

These fuel dstributors are dirt cheap used at your local Pick and Pull. Keep on the look out for one. Someone told me once, that a bad electric fuel pump can also cause a full rich problem? Not sure about this but he explained that the fuel pressure from the electric fuel pump controls the mechanism in the fuel distributor which regulates fuel mixture.

Anyway it sounds like you got a great deal. If you need someone to take this headache off your hands let me know

pch2021 · #7 04-06-2009, 01:19 PM

I know the issue here- the techs were not using any fuel pressure gauges. It is all about the fuel pressures when dealing with CIS.

If you don't know what they are, then you are just tinkering.

78280SE · #8 04-28-2009, 12:29 PM

Ok, this past weekend I put in a rebuilt fuel distributor. And did a basic tune-up. Plugs, distributor, and rotor.

I sprayed some ether on the sensor plate and it fired up. It would not stay running though. You have to keep the sensor plate depressed about 1/8 of an inch for it to stay running. As soon as you let go of the sensor plate it dies. And the depth that the sensor plate is in order for it to run is way to high of an idle.

I tried adjusting idle screw, but had no impact. I decided to just let it run for a while by sliding a screwdriver between the sensor plate and the bracket above the sensor plate to allow enough air to keep it running. I let it run for about 30 minutes but as soon as you remove the screw driver the plate closes and it dies. Not sure where to go from here. Also, when you push in the sensor plate and rev it up it blows huge amounts of black smoke. So obviously it is not burning off the fuel correctly or getting too much or not enough air.

The engine sounds very strong when revved up and even the a/c blows ice cold so I would love any tips that would help me get this thing back on the road. So far I have only put $300 in this car after buying it for $200 and it's almost running.

I know I should take it to a Mercedes mechanic, but I want to try and fix this on my own so I understand the system for future problems.

Please let me know any tips or websites with instructions on this. I have search many sites but cannot find a problem with these exact issues.

Let me know.

Thanks

mercman28 · #9 09-19-2009, 05:05 PM

Hello,just read your post about the problems you are having with your mercedes.i am having the same problems with mine,my 1979 280se will not run or tickover unless i hold the sensor plate down with a screwdriver to keep the car ticking over,even when the car is running,it runs rough and seems to be misfiring,just wondered if you managed to get yours fixed and what was the problem if you did get it sorted.Any info would be much appreciated..Cheers Mark....

ctaylor738 · #10 09-19-2009, 08:24 PM

You probably have high control pressure caused by a malfunctioning warm-up regulator or a sticking piston in the fuel distributor.

Read through this post.

Where to go from here?

You should really do some self-education and get set up with a pressure gauge, or you will just be guessing.

kelvin1018 · #11 10-13-2009, 02:36 PM

hey I have a 1979 280 se benz,the car take some time starting up but once its running it putters.I can drive it for about 30min then it starts cuting off then i crank it and it will go but will cut off at next stop sign.
i have change plugs,and had the timing reset and distributor as well.
i realy need help.
Thanks.
gman

ctaylor738 · #12 10-13-2009, 04:16 PM

The first thing I would check is the tank strainer for clogging. Crud or rust can get sucked into it and eventually starve the engine. Let it sit for a few minutes and without suction from the pump, the crud moves around and enough fuel gets to the pump to keep the engine running for a little while.

gs sparhawk · #13 10-16-2009, 12:30 AM

Chuck is the MAN here with the CIS. Just to add,-the injectors squirt fuel into the intakes just ahead of the valves and will keep squirting if there is pressure to the distributer and fuel available. Then the cylinders with open valves fill up. The Cold Start Valve, the Warm Up Regulator and fuel pump all can contribute to the problem and a run-through of the whole system is in order if it has not been running for awhile. Check on the quality of the old fuel--change any filters you can find----------also, the tank can become grungy.

I'm going through mine for the same reasons you are and this forum has been enlightening. And I really appreciate it.

Sparky

stickandrudder · #14 10-16-2009, 05:59 PM

Ignoring the attempted thread hijack above:
Disconnect your fuel return line and run it into a container with a piece of hose.
If the car now runs fine you have a blocked fuel return line, probably the short hose where it enters the fuel tank.
A check with a fuel pressure guage would reveal something like 9 bar pressure.