Mechanics

IGNITION QUESTION

1989 Mercedes Benz 300se

Engine Mechanical problem
1989 Mercedes Benz 300se 6 cyl Two Wheel Drive Automatic 135000 miles

This 300se was running perfectly. Drove it to town and shut it off. Came back out a hour later and it wouldnt start. Towed it home and started looking into what the prob was. It seems to be getting fuel. Even gave it a little shot of starting fluid with no effect. Chwcked spark at the plugs and it at time had none, and other times it would have a intermittant weak spark. Installed new cap, rotor, wires and plugs. Checked spark at the plugs and it has none, BUT, now here is the good part, but it has good constant hot spark coming out of the coil wire going into the dist cap, but nothing coming out to the plug wires. Have swapped out the cap and rotor back to the original ones with no change. Pulled valve cover and checked timing gear condition. All looked to be fine. I decided it must be the crank position sensor so reploaced it with new, still no spark to the plugs. Swapped out the black ign mudule where the crank sensor attaches to along with 2 wire looms and a vacume line, still no fire going thru the dist. It about has to be firing the coil while the rotor is between contacts in the cap. Once in a while it will get a intermitant spark to the plug wires, and on rare occasion it will even hit as I let off the key but seems to be firing out of time as it will try to turn backwatds. Again, I am pretty convinced its firing the coil so far out of time that it is jumping inside the dist cap to the wrong lug occasionally. The module I swapped onto it was a second hand one, so possiblky could also be bad, but if thats not it what else could it be. Im running out of hair to pull out with this thing. Any help appreciated.
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Kansas cat
July 24, 2010.




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