Electrical run out

[78DiMarco]

When I changed my ignition system from a Mallory single point to MSD electronic I now get what one mechanic called "run out". Now when I go to shut the motor off it keeps running but all the other electrical items shut down. I ran a second ciruit with a separate switch to the MSD so I can kill the motor as a temporary fix. One person says "get a two circuit ingnition switch". Another person told me I need to have the alternator checked that there is a resister or diode blown that is letting power from the alternator feed the ignition which it turn won't allow me to kill the motor with my original single ingnition switch.
Has anyone run into this problem and what is the best cure? I really hate having two ingnition switches and I think it could be dangerous if you need to shut off fast. eek! I heard this is a common problem when switching to MSD.
Thanks for the help.

[Craig]

78DiMarco:
Another person told me I need to have the alternator checked that there is a resister or diode blown that is letting power from the alternator feed the ignition which it turn won't allow me to kill the motor with my original single ingnition switch.Some set-ups do require a diode to be spliced into the main power line that prevents the juice from the alternator from feeding back into the MSD causing just this run on situation. Check with the MSD tech line at (915) 855-7123. They can get you what you need.
Craig
[ January 27, 2003, 04:38 PM: Message edited by: Craig ]

[Cheyenne 572]

I have the same problem as you but i can kill the motor with my kill switch.I see that JEG'S has a product that will cure that it's called a charging system shutdown relay and it cost's $40.00 for it.Don't know if it work's or not but if you find out how to remedy this let me know.Later
Cheyenne 572

[Infomaniac]

The MSD web site tells you how to fix this. I saw it a few weeks ago. Caused by a very small residual voltage.

[MikeF]

I had this problem too.
This was MSD's reply:
The problem you have described is easily fixed with diode that is supplied in the parts bag of the 6a unit. If you do not have this diode, then your local radio shack or electronics shop can help you. The diode is 1 amp 200 volt or up to 1 amp 500 volt will work. Refer to the trouble-shooting guide in your installation instructions under "engine run-on".
If you do not have the instructions, then follow these steps:
1. Locate your main field wire on your alternator or external voltage regulator.
2. Install the diode on this wire with the white stripe facing the alternator or regulator.
This should take care of the problem.

[78DiMarco]

Sounds like there is an easy fix. I was getting sick of dealing with the extra kill switch!
Thanks everyone!

[Cheyenne 572]

Will that work on a single wire alternator?I have the one wire going to my starter is this ok or should i take it to my battery kill switch?I know i'm asking alot of question's.I was told the reason way mine is doing this is because my 100amp alternator is self energizing the system.Later
Cheyenne 572

[MikeF]

Cheyenne 572:
Will that work on a single wire alternator?I have the one wire going to my starter is this ok or should i take it to my battery kill switch?I know i'm asking alot of question's.I was told the reason way mine is doing this is because my 100amp alternator is self energizing the system.Later
Cheyenne 572 It will not work w/ the one wire alt. One wire going in and feilds are excited internally. Feeds the voltage created....back to the battery via the ONE wire. cry .

[Cheyenne 572]

Ok thank's for the info. do you have any idea's how i can fix this.Later
Cheyenne 572

[MikeF]

572, You can use it as you already are doing it (w/ the kill switch), or use a relay (as is the earlier post) to only the power feed to the coil (not the charging circuit) to shut the engine off. boxed