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mercadies 280CE
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50 Posts
Discussion Starter #1
When id changed the fuel filter she ran well?Next morning she began well,after a mile or two began missing.I turned back,after 3000rpm she ran well but i could feel her wanting to "go" but holding back

Whats wrong?Could the fuel pump be failing?Sounds alright
 

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1979 280CE
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6,118 Posts
How old are the plugs, rotor, cap, and wires?
 

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mercadies 280CE
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50 Posts
Discussion Starter #3
The plugs are new the rotor cap costs $90! Thats why i didnt "buy & try" The cap "looks" fine, not worn.

The other reason is she runs soooo well for a day perhaps two no hesitation no missing ,just a real pleasure.When it was damp some fine rain i sprayed with WD40 that time she ran perfectly which was good as i dident have another car & HAD to collect an exhaust

Shes never let me down,but when im just "driving about" going places that could wait then she sometimes runs very badly as yesterday.I havent tried this morning but she might just run perfectly or not??

The injection dosent have complicated oxygen heat sensors ?? It feels as if the fuels being restricted I did look at the distributor which is magnetic??Isent it??
 

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mercadies 280CE
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50 Posts
Discussion Starter #4
She been sitting in the drive overnight & all morning i left her running really badly.Now i started ran with a bit cold start warmed up ran perfectly.Tick over 800/900rpm Let her sit as if in traffic(on an empty road) drove slowly stopped perfect.

When she starts running baddly the rpm at tickovers about 600rpm & lumpy then depending on how bad shes running when i reach 2000rpm or on otherdays 3000rpm she "clears" and sounds wonderful as i hope there arnt speed controls!

Yesterday she had a rare bad day when she just ran badly lumpy even after 3000rpm On those days if i stop & the engine stops its very hard to start,when it starts seems to be running on "2" or 3 to move without stalling i have to go to 1400rpm at least then engage drive & "bang" get moveing then in low to keep going

Next day or even a few hours later she might run well again????
 

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EURO 280CE
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1,689 Posts
the dist cap is like 40 at autohaus i just picked one up, comes with the cover too.

my car was dying while hot with the idle at 1k(you would think with it that high it shouldnt me missing) at stop lights the thing would just quit, so i kept having to put it in neutral.

i changed the filter and it was fine, but there is still an obvious miss at anything under 1100rpm. it seems we have similar issues.

so i just changed my cap and wires and nothing changed, only more top end power which didnt even feel bad to me in the first place.
but i knew it was something else cause you cannot adjust the cold idle, with the screw
 

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1978 280ce euro found dead on Ebay
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1,805 Posts
He's in France they have Ouch prices on parts. That the cp off and look for any cracks inside or outside. Scrape the copper parts under the cap where rotor spins and remove oxidation. Put it back on and spray silicone over the cap and spark wire connections to help keep moisture out. See if that helps. It might also be the ignition control box and you don't want to know how much that is.
 

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1978 280ce euro found dead on Ebay
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1,805 Posts
Underhood, driver's side fender over by coil near headlight a silver box mounted on inner fender wall has two round plugs on bottom one small and one large. This is the electronics for ignition.
 

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mercadies 280CE
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50 Posts
Discussion Starter #9
Found it!

I pulled carefully the plugs out & the contacts look in perfect condition as if they were new so i didnt use contact cleaner.

I followed the green wire to the distributor all was well.

My hand touched the vacuum pipe from the dizzy to the injection pump and it came off at the pump end??(It heads in that direction hidden under the air filter intake etc)

With the vacuum pipe disconected the engine started at once and ran perfectly cold at 1100rpm

Ill reconnect it later but what happens if i run without the vacuum (advance??) connected??
 

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1978 280ce euro found dead on Ebay
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1,805 Posts
Found it!

I pulled carefully the plugs out & the contacts look in perfect condition as if they were new so i didnt use contact cleaner.

I followed the green wire to the distributor all was well.

My hand touched the vacuum pipe from the dizzy to the injection pump and it came off at the pump end??(It heads in that direction hidden under the air filter intake etc)

With the vacuum pipe disconected the engine started at once and ran perfectly cold at 1100rpm

Ill reconnect it later but what happens if i run without the vacuum (advance??) connected??
There are two vacumn lines to distributor, One is for retard and one is for advancing. What happens has to do with which vacumn line you have off.

It's possible you had them crossed and that was your problem.
 

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mercadies 280CE
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Discussion Starter #11
I never noticed the second line!!Its the front (red on mine)line thats off.Where "should" it go to?

Im going to take off the air filter now,ill put the line back from where its come for now

I wouldent know if they were reversed.I just got another workshop Manuel from ebay ive been sent the diesel one!I now have 2 Diesel 123 manuals!Eventually ill get one for a gas 123 with luck,the postage to change it costs more than the manual
 

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1984 Mercedes Benz 280E
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126 Posts
Me 280E is have, what sounds like, the same problem. When I first start it up in the mornings it runs horrible cold. It jerks and feels like it just wants to die. It will be fine once it is warmed up for about 10 miles then the jerking happens in high rpms or going up hill under a load. When I come to a stop, the car wants to just stall.
 

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1984 Mercedes Benz 280E
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126 Posts
Alright the jerking is still going on with my 280E. I have noticed that it runs fine till I get to about half a tank. Could my problem be the fuel pump? I changed the fuel filter recently and the filter was larger than the one that was on there first. Could the larger fuel filter have anything to do with it?
 

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1984 Mercedes Benz 280E
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126 Posts
Alright so I think I am going to go ahead and change the fuel pump. I want to get the Bosch fuel filter too, but I don't know which one I need to buy. Should I buy the 75mm or the 82mm in diameter? When I first got the car it had a smaller fuel filter on there. The one I recently installed is larger in diameter and length, so I am guessing I should go with the smaller 75mm filter?
 

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1984 Mercedes Benz 280E
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126 Posts

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1984 Mercedes Benz 280E
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126 Posts
I installed the fuel pump, fuel filter, and went ahead and did the plugs, plug wires, and distributer cap while I was at it. The car runs fantastic! The fuel pump that was on there before was not the factory one and had a lot of visible trash in it, I guess from where the car sat for two years.
 
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