No start problem - Mercedes-Benz Forum

 
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post #1 of 7 (permalink) Old 11-11-2012, 02:23 PM Thread Starter
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No start problem

I have a 1989 300e. One morning while driving to work, the car started stumbling and missing. The only way I could keep it running was to fully depress the throttle. Upon arriving at work, the car died hasn't run since. I have replaced the fuel filter, checked the fuel flow output on the return side of the fuel distributor and am getting the proper fuel flow. I have also replaced the coil and am getting an intermittent spark, according to my timing light. After cranking the engine, the spark plugs are wet.

Any help would be greatly appreciated....
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post #2 of 7 (permalink) Old 11-11-2012, 02:36 PM
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check your crank shaft position sensor. thats the one that gives the signal to EZL, ignition module, to fire the coil. disconnect the sensor from EZL and measure the resistance, I think it should be around 700-900 Ohms, i might be wrong. if resistance within specs, try to beasure the voltage while someone cranking the engine. It should show some voltage, I dont remember what are the specs. Maybe someone will give you the right numbers.

'93 Crown Vic 188,600 after 7 years ended up in police impound
'97 Nissan Maxima 212,315 (Sold)
'90 560SEL 198,375(Sold). Will be missed dearly.
'97 S500 Black on mushroom. 137,000 miles

Last edited by abdimona; 11-11-2012 at 02:42 PM.
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post #3 of 7 (permalink) Old 11-11-2012, 02:46 PM Thread Starter
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Thanks for the reply. I have a digital ohm and dwell meter but my manual doesn't show me how to test or locate the crank position sensor.
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post #4 of 7 (permalink) Old 11-11-2012, 03:07 PM
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Quote:
Originally Posted by sharkbait1964 View Post
Thanks for the reply. I have a digital ohm and dwell meter but my manual doesn't show me how to test or locate the crank position sensor.
you might find an answer if you search the forum. did you check your basics? plugs, rotor, wires. Obviously you have air and as far as you mentioned you have fuel. The only thing missing is the spark. Now, on my w126 the EZL is on the drivers side wheel well. It has 2 round connectors at the buttom, one vacuum line and crank position sensor on top. Try to see if you have the same layout.

'93 Crown Vic 188,600 after 7 years ended up in police impound
'97 Nissan Maxima 212,315 (Sold)
'90 560SEL 198,375(Sold). Will be missed dearly.
'97 S500 Black on mushroom. 137,000 miles
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post #5 of 7 (permalink) Old 11-11-2012, 03:17 PM Thread Starter
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Yes, I have checked the basics. I have located EZL unit, but my question is, where is the CPS itself located? I have heard it is in the general area of the starter. Also, most CPS sensors that I am familiar with, are of the hall effect type i.e..magnetic pick up. Does there a test exist of this type? And where can I locate the wires to test it?

I will also search the forum. Thank you
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post #6 of 7 (permalink) Old 11-11-2012, 03:38 PM
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Quote:
Originally Posted by sharkbait1964 View Post
Yes, I have checked the basics. I have located EZL unit, but my question is, where is the CPS itself located? I have heard it is in the general area of the starter. Also, most CPS sensors that I am familiar with, are of the hall effect type i.e..magnetic pick up. Does there a test exist of this type? And where can I locate the wires to test it?

I will also search the forum. Thank you
It should connect to your EZL. there are 4 marks on your flywheel, every 90 degrees. once the engine rotates the Crank sensor sends a pulse to EZL to trigger the coil at that point the EZL grounds the pulse going to coil and you have a spark. the Crank position sensor is located somwhere in the back of the engine, you probably will have to climb under the car. However, you can disconnect it from EZL and test the resistance while the car is off and if it is within the specs. let someone crank the engine and measure the voltage it gives you at the same connection.

'93 Crown Vic 188,600 after 7 years ended up in police impound
'97 Nissan Maxima 212,315 (Sold)
'90 560SEL 198,375(Sold). Will be missed dearly.
'97 S500 Black on mushroom. 137,000 miles
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post #7 of 7 (permalink) Old 11-11-2012, 07:03 PM
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if cap / rotor is original , replace .
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