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1977 280e
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39 Posts
Discussion Starter #1
After checking all voltages and resistances, replace cap and rotor. Any ideas as to why this car won't start after setting for 18 months. It ran before it was parked.
 

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1984 300D
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5,070 Posts
If this is a Engine with a Carburetor I have seen the Needle Valve in the Float Chamber get stuck before. If it gets stuck you will not get Fuel into the Carburetor.

Also I have taken the Carburetor apart on my Truck that sits for like a year or so and when you take it apart all of the Gasoline is evaporated but there is a white powdery residue left inside that sometimes plugs up passages.

Since I am kind of a thrill seeker when trouble shooting I have been know to pour like a Teaspoon of Gasoline into the Intake Manifold (through the Carburetor) just to see if it will try to start like that. If it tries to start when I do that I know it is a problem of not getting Fuel. (Note: when you dump Gas down through the Carb if your Engine back fires there is a small chance of the Carb catching fire so be prepared.)

You can do the same with Starting Fluid but you need to be more careful. Have someone else try to start the Engine while you are careful to use only enough Starting Fluid to see if the Engine tries to start.

If it is a Fuel Injected car it could have a similar issue of deposits building up in one of the passages and Fuel Injection Systems also have a Fuel Pressure Regulator that is often a Diaphragm that can get old and stiff.
 

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1984 300D
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5,070 Posts
The problem is in the ignition. Fuel delivery is ok. Just no spark.
"After checking all voltages and resistances, replace cap and rotor. Any ideas as to why this car won't start after setting for 18 months. It ran before it was parked."
Because you did some electrical checking I thought the you had Spark.

As far as the Ground goes all of the wiring connections including the Ground have to be good in order to complete the electrical circuits.
 

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1984 300D
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5,070 Posts
(I did not realize that this car had Ignition Points.)

Apparently from the below quote from the Manual the Ignition Points can get coated or burned. So I would check that.
"Removing, preventing formation of layer on breaker points (breaker-controlled transistorized ignition)"

(Not on a Mercedes) Besides the Contact area getting burned up on Points I have had the little plastic step on the Points that rides on the Distributor Cam break off before. I have also had the screw/s that hold the points adjustment come loose causing the Points to remain closed.
I have also had issues where the Spark Plug/Coil Wire/s contacts were Corroded inside of the Distributor Cap.
I have even had the Coil wire develop an open circuit. (Test the resistance with an Ohm Meter; if it has infinite resistance it is no good.)

If you have a Volt/Ohm Meter you can test the resistance of the Ignition coil to be sure that is good. If you do not have an Manual that tells you how to do this there should be some info on the internet.
 

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1984 300D
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5,070 Posts
Apparently there is 2 resistors in the circuit. A 4 ohm and a 6 ohm one.

I suppose it is possible for them to be no good also.
 

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77 280E, 78 450SEL, 86 300E, 87 300E, 90 300E, 92 400E & 4 scooters
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233 Posts
Koruldon, I have a 1977 280E and just replaced the coil. The coil was in working order when replaced last week.

If it'll help I'll ship it to ya, n/c.

Anything I can do to help, say the word.
 

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1977 280e
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39 Posts
Discussion Starter #9
I was just thinking. There is a lot of corrosion between the ignition control unit and the body. Does the control unit ground through the body?
 

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1991 300zx 2+2 @ 129k Miles.
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194 Posts
(Note: when you dump Gas down through the Carb if your Engine back fires there is a small chance of the Carb catching fire so be prepared.)

You can do the same with Starting Fluid but you need to be more careful. Have someone else try to start the Engine while you are careful to use only enough Starting Fluid to see if the Engine tries to start.
I acquired 3rd degree burns up my right arm shoulder and side of my head about 8 years ago when a co-worker did exactly what you warned about....He turned the car over while I was pouring gas into a carb. Use Choke spray, and make sure that there is no chance of the engine turning over while you are under the hood
 

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1977 280e
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39 Posts
Discussion Starter #12
Does anyone know if the ignition control unit is ground through the contact with the body. Mine has a lot of corrosion built up between the back of the ignition control unit and the body.

Thanks
 
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