No amp draw when ignition switch pulled on

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brian c
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Tractors Owned: 1957 Farmall Cub
Location: MS, Hernando (Memphis area)

No amp draw when ignition switch pulled on

Postby brian c » Tue Jun 19, 2018 4:45 pm

Hello Cub friends. It's been a long time since I've been on here - fortunately because my Cub has been very reliable. I have a 57 Cub that still has the 6v positive ground system with battery ignition. It ran fine when I mowed a week ago. Today I tried to start it, and it fired for just a second, then nothing. The starter is turning the engine over fine. I notice that when I pull the ignition switch on I am not getting any discharge indication on my ammeter. I normally do have see a slight deflection when I pull the switch. I put a voltmeter on the switch side of the coil and I see 6V. I then put the voltmeter on the distributor side of the coil and I also see 6V - all the time. Even as I turn it over with a hand crank. Is it time for points and condenser work/replacement? I'd appreciate any troubleshooting tips. Thanks!

Jim Becker
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Re: No amp draw when ignition switch pulled on

Postby Jim Becker » Tue Jun 19, 2018 5:11 pm

The trouble is at or near the points. Either:
1) The contacts are too dirty/corroded to conduct. (file or replace them)
2) Something has happened that is keeping the points from physically closing, for example the spring that closes the points broke. (adjust or replace them)
3) A wire/connection somewhere between the distributor side of the coil and the points arm is broken. (reconnect or replace the broken conductor)
I guess to be complete, I should mention that the distributor could have lost its ground somewhere between the points plate and the chassis. That is a pretty long shot.

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Glen
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Re: No amp draw when ignition switch pulled on

Postby Glen » Tue Jun 19, 2018 5:36 pm

Hi,
Below are pages from the late 1955 Cub owner's manual that show the points. The point surfaces have to be clean, flat, and not burned for the engine to start good.
The ignition timing should be checked with a timing light, after you get it to run. The timing affects the starting, and the engine's power. :)

http://farmallcub.com/rudi_cub/www.clea ... e%2041.jpg

http://farmallcub.com/rudi_cub/www.clea ... e%2042.jpg

The distributor cap contacts, rotor, ignition wires, and spark plugs, all need to be good for the engine to run good. Dirty spark plugs can cause hard starting.

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brian c
10+ Years
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Posts: 94
Joined: Thu Oct 06, 2005 1:08 am
Zip Code: 38632
Tractors Owned: 1957 Farmall Cub
Location: MS, Hernando (Memphis area)

Re: No amp draw when ignition switch pulled on

Postby brian c » Sun Jun 24, 2018 4:36 pm

Thanks for the help Jim and Glenn. I didn't have a whole lot of time to troubleshoot, and parts are fairly cheap, so I replaced the points, condenser, rotor, and distributor cap. Purrs like a kitten again. Hardest part was getting to the little mounting screw when installing the new condenser.

-Brian

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Glen
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Posts: 3508
Joined: Mon Mar 19, 2012 7:33 pm
Zip Code: 00000
Tractors Owned: 1956 Farmall Cub with Fast Hitch, F-11 plow, Disc, Cultivator, Cub-22 mower
Circle of Safety: Y
Location: Wa.

Re: No amp draw when ignition switch pulled on

Postby Glen » Sun Jun 24, 2018 5:46 pm

Hi,
Nice you got it to run again. :)

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John *.?-!.* cub owner
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Re: No amp draw when ignition switch pulled on

Postby John *.?-!.* cub owner » Sun Jun 24, 2018 10:24 pm

brian c wrote:...... Hardest part was getting to the little mounting screw when installing the new condenser.

-Brian
One of these screw starters works great for that, though you may need to cut it off to have enough room.
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Clark Thompson
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Re: No amp draw when ignition switch pulled on

Postby Clark Thompson » Fri Jun 29, 2018 9:19 am

Just a thought. On the 55 and newer cubs the ignition is wired through the voltage regulator. If the voltage regulator contact points are corroded and have bad contact then you wont get power to the coil. My 57 loboy sets quite a bit so sometimes it will start but quit after a few minutes. I usually have to take the cap off the regulator and clean the points.Then all is well for a year or two.This also happens on my 1975 cub also
Collector of Farmall cubs and cub cadets.Injoy helping people keep their cubs running. Years of experipnce.

Jim Becker
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Re: No amp draw when ignition switch pulled on

Postby Jim Becker » Fri Jun 29, 2018 9:44 am

I don't believe that the BAT to L connection inside the regulator goes through any of the contacts. Clean cut-out and regulator contacts are both certainly required for the generator to supply power to the ignition and recharge the battery.


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