Pilot Mike
New User
Got a Farmall B with a magneto. Tractor will not start with starter, cranks great, but will start immediately if pulled or just rolled down small hill. Runs great when running.
- Thread starter Pilot Mike
- Start date
rustcollector
Member
- Location
- Starkville, MS
Pilot Mike,
Do you hear the magneto impulse coupling clicking when the starter is turning the engine? A non functioning impulse can make for hard starting with starter or crank.
Do you hear the magneto impulse coupling clicking when the starter is turning the engine? A non functioning impulse can make for hard starting with starter or crank.
Pilot Mike
New User
yes it snaps when engine is turning over by starter or crank. sends spark to through all plugs too. plugs are good.
Janicholson
Well-known Member
Set the points after cleaning them with 400 grit and a folded dollar bill to wipe them clean. Point gap is .013". If off, the spark will be weak at low speeds. Be sure to mark the position of the rotor and reinstall it correctly to keep the rotor timed. it has gears. Jim
Jim in Ma.
Well-known Member
Time to check your Mag. If the springs are weak it will start like that. You should hear a distinct snap from the impulse when cranking the engine over.
Pilot Mike
New User
Cleaned and set the points Already. Still refuses to start. Starting to wonder if the magneto may just be a little to weak to get it running but will start if it pull starts
When did this start? any changes made that brought it on? Was it ok, then just started happening? Or is this a new to you tractor?
Having read the other suggestions - I'd add to check the timing.
It should snap right at tdc on the #1 cylinder on the compression stroke.
Might be retarded too far - but advances to an acceptable range once the mag gets spinning fast enough to advance it.
?
Having read the other suggestions - I'd add to check the timing.
It should snap right at tdc on the #1 cylinder on the compression stroke.
Might be retarded too far - but advances to an acceptable range once the mag gets spinning fast enough to advance it.
?
Janicholson
Well-known Member
Trip point on the mag might be worn! Pull it slow as cranking to see if it is just speed related. Also there could be issues with the magnetic field of the Mag Magnets. They can be charged to make them as strong as new. Old mag shops have them. Search the archives for Magnet charging. Jim
gene bender
Well-known Member
Your rotor isnt ,ined up with the cap when it fires. There are gears that turn the rotor. Make a mark on the body where the cap sets at the tower on the cap. Then remove the cap and watch where the rotor is when it snaps. Cause the rotor will turn and stop where it snaps it then should be pointed at the mark. Just one tooth off will cause problems. You know you have fire because it starts and runs when pulled. So make sure of the rotor where its pointed when it snaps.
teddy52food
Well-known Member
One tooth off doesn't make any difference with a hot mag. I find a lot of them timed between the L&R marks. Best to open the cover (2 screws) and check it to be sure. The rotor should line up with a terminal in the cap when the points break. It is past that after the impulse snaps.
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