1984 Mercedes 500 SEL won't start - not getting spark out of distributor

There is a spark control modal in the distributor most books do not tell you about it . if you have replaced everything else try that

at rear of engine ,flywheel 5mm allen key or 10mm socket

check all wires to starter motor for bad earth.....make sure power reaching starter motor.....check starter motor isnt stuck

This just happened to my Dad's 1998 GMC Safari...

Firstly...

Check the hard vacuum line as previously noted by others.
If that's ok, then take off the intake pipe and spray brake clean into the throttle body while trying to crank it.

If it starts.. then you have a fuel related issue, if it doesn't start then you have an electrical related issue.

Our van did not start after trying to use brake clean.

Take off the console inside the vehicle's cab and get at the distributor.

Usually people noted that the ICM (ignition control module, inside the distributor) was the main issue here, but on our van, the distributor and wires looked brand new so it was probably recently changed (we got this van 5 months ago), so I assumed the spark plugs were also changed at the same time.

We unplugged the connection from the coil to the distributor, tried to crank it, and no spark was being generated, boom, got a new coil and starts up fine.

Just takes a bit of trial and error.

see this steps and fix it. God bless you
When the engine cranks normally but won't start, you need to check ignition, fuel and compression. Ignition is easy enough to check with a spark tester or by positioning a plug wire near a good ground. No spark? The most likely causes would be a failed ignition module, distributor pickup or cranshaft position sensor CKP

A tool such as an Ignition System Simulator can speed the diagnosis by quickly telling you if the ignition module and coil are capable of producing a spark with a simulated timing input signal. If the simulated signal generates a spark, the problem is a bad distributor pickup or crankshaft position sensor. No spark would point to a bad module or coil. Measuring ignition coil primary and secondary resistance can rule out that component as the culprit.
Module problems as well as pickup problems are often caused by loose, broken or corroded wiring terminals and connectors. Older GM HEI ignition modules are notorious for this. If you are working on a distributorless ignition system with a Hall effect crankshaft position sensor, check the sensor's reference voltage (VRef) and ground. The sensor must have 5 volts or it will remain permanently off and not generate a crank signal (which should set a fault code). Measure VRef between the sensor power supply wire and ground (use the engine block for a ground, not the sensor ground circuit wire). Don't see 5 volts? Then check the sensor wiring harness for loose or corroded connectors. A poor ground connection will have the same effect on the sensor operation as a bad VRef supply. Measure the voltage drop between the sensor ground wire and the engine block. More than a 0.1 voltage drop indicates a bad ground connection. Check the sensor mounting and wiring harness.
If a Hall effect crank sensor has power and ground, the next thing to check would be its output. With nothing in the sensor window, the sensor should be "on" and read 5 volts (VRef). Measure the sensor D.C. output voltage between the sensor signal output wire and ground (use the engine block again, not the ground wire). When the engine is cranked, the sensor output should drop to zero every time the shutter blade, notch, magnetic button or gear tooth passes through the sensor. No change in voltage would indicate a bad sensor that needs to be replaced.
If the primary side of the ignition system seems to be producing a trigger signal for the coil but the voltage is not reaching the plugs, a visual inspection of the coil tower, distributor cap, rotor and plug wires should be made to identify any defects that might be preventing the spark from reaching its intended destination.

Hi, if an engine cranks but refuses to start, it lacks ignition, fuel or compression. When the engine cranks normally but won't start, you need to check ignition, fuel and compression. Ignition is easy enough to check with a spark tester or by positioning a plug wire near a good ground. No spark? The most likely causes would be a failed ignition module, distributor pickup or crankshaft position (CKP) sensor.

check fuel pressure and then compression

It is necessary to place the No. 1 cylinder in the firing position to correctly install the distributor. To locate this position, the ignition timing marks on the crankshaft front pulley are used.

Remove the No. 1 cylinder spark plug. Turn the crankshaft until the piston in the No. 1 cylinder is moving up on the compression stroke. This can be determined by placing your thumb over the spark plug hole and feeling the air being forced out of the cylinder. Stop turning the crankshaft when the timing marks indicate TDC or 0.

Oil the distributor housing lightly where the distributor bears on the cylinder block.

Install the distributor so that the rotor, which is mounted on the shaft, points toward the No. 1 spark plug terminal tower position when the cap is installed. Of course you won't be able to see the direction in which the rotor is pointing if the cap is on the distributor. Lay the cap on the top of the distributor and make a mark on the side of the housing just below the No.1 spark plug terminal plug terminal. Make sure that the rotor points toward that mark when you install the distributor. On the VG30i, align the mark on the distributor shaft with the protruding mark on the housing.

When the distributor shaft has reached the bottom of the hole, move the rotor back and forth slightly until the driving lug on the end of the shaft enter the slots cut in the end of the oil pump shaft and the distributor assembly slides down into place.

When the distributor is correctly installed, the breaker points should be in such a position that they are just ready to break contact with each other or a lobe of the reluctor is aligned with the stator contact. This is accomplished by rotating the distributor body after it has been installed in the engine. Once again, line up the marks that you made before the distributor was removed from the engine. On the VG30i, the distributor rotor should be in the 11:25 o'clock position (between 11 and 12 o'clock).

1. Install the distributor hold-down bolt.
   
2. Install the spark plugs.
   
3. Install the cap, primary wire, and vacuum line(s).
   
4. Install the spark plug leads. Consult the marks made during removal to be sure that the proper lead goes to each plug. Install the high tension wire if it was removed.
   
5. Start the engine. Check the timing and adjust it if necessary.
   
   
   Hope this helps, be sure to upvote if it does :)
   

If there is no spark, either no electrical at the primary coil or the coil is not working.
if you already measure primary/ secondary resistance to confirm it is OK. Here is to test it - making electric pulsed signal at the primary terminals to see it spark at the secondary terminal.
You want to confirm everything works from the coil, so you can find out what causing the coil is not working. Here are what to check the coil before a replacement::
1- Disconnect the Positive cable on the battery.
2- Hook a spark plug directly to the coil wire ( the one coming to the center of distribution cap)
3- Find a long double wire so you can connect from the terminals of the primary coil to the battery.
4- Connect each wire end to the terminal of the primary coil. It doesn't matter which polarity.
5- Connect 1 wire to the chasis ground.
6- Hold the other wire and quickly swipe it over the positive terminal of the battery. Reapeat it until are sure that you get spark or not.
7- You should see or hear a spark. If this is the case your coil is good. If itis not, your coil is bad and it need a replacement. Problem is solved.
4- If the coil is good, the problem would be from the Primary of the coil back to the ignition key: No electrical signal to turn on the coil.

hello,your firing order 1-5-4-8-6-3-7-2,,,standing in front,left side of your engine is your cylinder 1 to 4,remove your valve cover then rotate your crankshaft,using 27mm socket,observe the movement of camshaft,and look for the timing mark in crankshaft,(ot) then you can install your high tension wire,begin on cylinder number 1,ty