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  #1  
Old 06-22-2008, 02:32 PM
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Red face 1967 250S starts and dies...have Electronic ignition now

Hi all. I have a 1967 250S I'm trying to get going. Inline 6 - 2.5 liter dual carbs. It sat for 3 years, and I just put a ''hot spark" on it. It fires and starts for about 3 seconds and dies. The previous owner said he had problems ''shutting it off" after it ran. Ignition key bad? Carbs plugged? It squirts a little fuel from the fuel pump at the carb intake. I'm just wondering if I should start on the the carbs, or ignition next....?? Is there some kind of sensor or something I'm missing? Any help will be appreciated.. In addition, I will take pictures of the ''hot spark'' and post them. It works well. By the way, the hot spark had to be ''re engineered'' by myself; however , it is an easy fix to make it work on a '67 benz..probably early cars as well.


Last edited by flacollect; 06-22-2008 at 03:42 PM. Reason: adding things
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  #2  
Old 06-22-2008, 02:37 PM
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Double check your wiring to your "hot spark". Make sure you have the "run" circuit and not the "start" circuit connected to the system.
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  #3  
Old 06-22-2008, 03:45 PM
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Quote:
Originally Posted by Mike D View Post
Double check your wiring to your "hot spark". Make sure you have the "run" circuit and not the "start" circuit connected to the system.
I agree.
Quick test is to run a jumper from the battery to the ballast and try it...that eliminate both run and start feeds...[ althoug 1967 models did not have ballast by-pass yet]
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  #4  
Old 06-22-2008, 10:30 PM
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Ok, last time I did that with my points it burnt up the points. There is a balast resistor next to the front headlights. It goes back to the ignition. I ran it with points, and the same thing happened. After I tried going from the battery to the positive terminal of the coil it fried the points. I don't want to fry the hot shot. It fire, and turns over now. The previous owner told me he couldnt ''shut the car off" and today after fiddling with it, the starter kept on running after i pulled out the key. I have a feeling it's the ignition key. I am not sure how to test it though, or even get to the key. Looks like it's way under there. Any help? Thanks.
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  #5  
Old 06-22-2008, 10:35 PM
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Question

The hot spark ignition has 2 wires....both go the the coil 1 positive and the other negative. That's it. Nothing else. It fires and works now where before it did nothing.
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  #6  
Old 06-22-2008, 11:26 PM
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Whenever bringing 12v power to ignition circuit from battery to diagnose a bad ignition sw or feed, you must bring it to the ballast resistors Key/Ign switch feed side, NOT the coil side...that is why you burnt the points.
That is why there is a Ballsat resistor in the circuit to begin with.
OHMS LAW...more resistance = less Amperage. The ballast is to protect the points from having to handle high amperage.
There is no difference of jumping the ign sw from battery pos or jumpering the switch contacts themselves , as long as you are BEFORE the ballast, not after, of course...meaning the ballast is in Series with the coil...
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Last edited by Arthur Dalton; 06-23-2008 at 12:05 AM.
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Old 06-23-2008, 11:07 AM
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Ok, thank you very much for the help. I will try it.
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  #8  
Old 06-23-2008, 01:38 PM
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Ok, after going from the balast resistor to the battery all I get is a ''clicking'' sound. I am not sure what this means. Any help? Thank you.
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  #9  
Old 06-23-2008, 11:53 PM
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I FOUND a bare spot on the wire harness. It was from an old battery leaking acid onto the wire. Thanks for all your input. Regards, David K.
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  #10  
Old 06-26-2008, 05:11 PM
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she lives

Negative ground cable was dirty. That was 1 of the many things wrong. Ignition switch must be ''held'' close the start positition to keep it running, but it runs. Needs the timing adjusted, and the carbs need adjusted; however, for an old car it sounds pretty darn good. Can't wait to get it on the road and see her run again, after sitting for quite a few years. AHHH YESSSSS 4 DOORS AND A/C.
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  #11  
Old 06-26-2008, 05:13 PM
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Smile Thanks. A Dalton.

Thank you for your service Mr Dalton. You have much knowledge, and helped me find my way through this adventure. I owe you a beer : )
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  #12  
Old 06-26-2008, 05:17 PM
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Thanks..I was working on these models when they were new.


If you have to keep the sw at start position, then the suspect is an open Ballast resistor.
Check for igntion 12v before the resistor with a test lamp when key is ON running position. If the test lamp is ON , then the ign sw is verified as OK, but the R can be open , meaning no power to coil.
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Old 06-26-2008, 06:08 PM
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Smile Mr Dalton, thank you again

You are a wealth of knowledge. Your information is worth it's weight in gold. Thank you. I checked the voltage and it is 12 volts in front of the balast resistor, so the ignition is not the problem but the resistor. However, I have changed to an electronic ignition.
The coil is a 1.8 ohm and some of the resistors I have seen are .4 ohm.

Should I buy a .8 ohm Balast Resistor for my electronic ignition now? Thank you again Mr. Dalton.
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  #14  
Old 06-26-2008, 07:12 PM
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You have a hall effect pick-up ignitor and you want to get as close to 3 ohms overall as possible..that will give you a good spark and at the same time protect the pick-up module.. your 1.8 and a .8 R will give you 2.6 , which will be on the hot side, but I would not worry about it. A 1.2 R would be ideal. Look at your instuctions ..these spec are from Pert, but I think they make that same module you are using.
The note at bottom is advised for either.

http://www.vintageperformance.com/retrorockets/avoiding_problems.htm

A main concern with these hall effect is the possibility of the magnet being in line when the key is on with engine not running.. [like when working on the car, etc] ..Many guys burn these units out b.c of this fault, but a trick is to put an in-line toggle switch for ignition so one can turn ign feed to coil OFF with toggle when needed .. you mount this somewhere hidden under dash and it then doubles as a theft device [ ign lock-out].
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Last edited by Arthur Dalton; 06-26-2008 at 08:46 PM.
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  #15  
Old 06-26-2008, 10:20 PM
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Cool Thanks again Mr Dalton

Wow, thanks what a great idea. I will get a toggle switch. In addition, I just ordered that resistor. Thank you again.

I just ran the car again, and lowered the passinger side electric window, and now it won't go up. Only down. The drivers side window makes noise like it wants to move, but won't. I don't know where to start on these, but while I'm waiting for parts I figure this is a good time to fix them. Any info. Again, Thank you Mr Dalton. You know stuff!!

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