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Old 05-03-2015, 03:48 PM   #1
Christoph
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Default Once i switch on the ignition....

Sorry
did a search, but couldnt find...
even i think i read something ...
years ago....


Once i switch on ignition, the amp-meter goes minus
So far, so normal.

Bad is, that it detects way more negative Amps , than it used to ...

Once i start the engine, everything seems to be ok.

What might cause the ampmeter to go as negative prior to start????

Any suggestions?
Thank you
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Old 05-03-2015, 03:58 PM   #2
ericr
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Default Re: Once i switch on the ignition....

are the points closed when this happens?
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Old 05-03-2015, 03:59 PM   #3
marc hildebrant
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Default Re: Once i switch on the ignition....

If the points are closed then the ammeter will deflect negative when the ignition is first turned on.

How much is the negative value ?

Marc
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Old 05-03-2015, 04:32 PM   #4
Mitch//pa
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Default Re: Once i switch on the ignition....

if the points are closed your normal... is your foot on the brake also? that could add more neg amps
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Old 05-04-2015, 10:33 PM   #5
Christoph
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Default Re: Once i switch on the ignition....

Thank you all. No brakelight for sure. Value was about 3 amps (just a little negative). No about 12 (?) Just enough to make me wonder .... went 200 miles yesterday. Seems to cause no prob....
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Old 05-04-2015, 11:13 PM   #6
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Default Re: Once i switch on the ignition....

pop the distributor cap off, pull the rotor and put an insulator (I used old credit cards sliced up) in the points to hold them open.

Turn on ignition. Should not have any draw.

If that is the case then something in your ignition circuit is now drawing extra power. (I would suspect the coil has an internal short but that usually will cause it to stop running. It could be such that it is providing a weak but adequate spark)

If there is current draw... you either have something else on the ignition circuit (tach?) or a component (condenser? wet wire?) is breaking down but not far enough to stop the ignition from working.

power goes from battery through ammeter to coil, through coil to switch, through switch to points, through points to ground. A couple of amps.

An additional 9 amps? I would find it before it starts smoking.
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Old 05-05-2015, 12:46 AM   #7
Mike V. Florida
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Default Re: Once i switch on the ignition....

Could also be a simple repop meter going bad.
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Old 05-05-2015, 02:09 AM   #8
Tom Wesenberg
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Default Re: Once i switch on the ignition....

If you show minus 3 then all is fine. The coil draws about 4 amps with the points closed and key on. When the engine is running, the coil draw will fall to about 1 to 1 1/2 amp draw.

The reason for the fall in amp draw is the points will be open part of the time, plus the coil primary acts like a choke when it sees pulses in current.
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Old 05-05-2015, 07:55 AM   #9
fiddlybits
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Default Re: Once i switch on the ignition....

Quote:
Originally Posted by Mike V. Florida View Post
Could also be a simple repop meter going bad.
Good point.
Not an ignition circuit item exactly but it is in the ignition circuit.
I have only seen them go dead so I hadn't thought of that one.

If you happen to have a VOM with a DC Amp jack (usually 10 amp and even the little cheapies have it...have shown this to a lot of EVers) you can do a quick test by removing the wire from the starter terminal and using the VOM, set up on DC amps (usually a dial setting plus moving the red lead to the A socket. Your meter may differ), to connect the wire to the terminal.

If the ammeter is going south (pun intended) then the VOM should show less than 3 while the dash ammeter is showing 12.
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