Farmal B not firing

rronch · Oct 31, 2010

I have a new toy. I have got it cranking over now but no fire. I changed the points, the plugs look good. Does have power from switch to coil.

I do believe it has been switched to 12 volt as it has an altenator on it. Is that a correct assumption?

Any suggestions?

John T · Oct 31, 2010

My Troubleshooting procedure linked below can help diagnose the cause of no fire in a battery powered coil ignition system.

Its possible to get a 6 volt Alternator and even possible to get one Pos or Neg ground, but Id say the majority of alternator conversions are indeed 12 volt and most alllllllll use Neg ground.

Does it have a 6 or 12 volt battery in it ????? Is it configured Pos or neg ground???

If the tractor was originally Pos ground and it got switched to Neg ground, the coil wires need swapped and likewise the ammeter if it has one.

http://www.ytmag.com/cgi-bin/viewit.cgi?bd=farmall&th=5745

John T
John Ts Ignition Troubleshooting

rronch · Oct 31, 2010

It did not have a battery in it. I hooked up a 12 volt POS to Pos and Neg to ground cable. If I tried to hook POS to NEg it would spark. With the 12 volt hooked up, the engine cranks real good. Just no spark that I can see.

Thanks for the trouble shooting tips. I will see if I can get this think started today.

old · Oct 31, 2010

With a battery hooked up try this. Pull the distributor cap off and the rotor and dust cover. Open and close the points by hand with the switch on. You should both hear and see a spark at the points. If you do not then either the switch is bad or the points need cleaned which is common even for new points since some company's put a little oil on them so as to keep them fro rusting etc. To check the switch just hot wire it

rronch · Oct 31, 2010

I guess the previous owner lost the dust cover as there is not one under the cap.

thanks

El Toro · Oct 31, 2010

Take a cotton swab and dip it alcohol and clean those new points. With your points open you should have voltage on both small terminals on your coil with the ignition switch in the on position. One other thing if your coil is the original 6 volt coil you may have cooked it with 12 volts. It should've had a ballast resistor before the coil. Hal

TractormanNC · Oct 31, 2010

If you hooked up the battery both pos ground and neg ground, your alternator is now toast. Buy a new alternator, hook it up neg ground, wire the coil and ammeter correct and be done with it.

gene bender · Nov 1, 2010

From you description its hard to say as you dont realy know what you have. The B Farmalls ALL came from factory with a Magneto system and over the yrs owners have changed stuff and added non factory stuff and so forth. There can be several things causing no fire to the plugs. I have several Bs most with factory Mags and 2 with add on dists one with I-H and other one is a Prestolite. Also Delco Remy made dists for them so what do you have.

rronch · Nov 4, 2010

I put a new 12v coil and the tractor started immediately. Not running very smooth but I am glad to know it runs. Not smoking but the straight pipe is roaring.

rronch · Nov 4, 2010

i put a new 12v coil and it fired off immediatley.

Farmal B not firing

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