John Deere A tractor, good battery, rebuilt generator,starter turns engine over, current to the coil,but no spark from distributor cap,terminals on cap check out okay. what might the problem be?

limited info generic answer pop can be anything check fuse and solenoid --check for spark --fuel to narrow down problem --no spark electrical problem --no gas fuel problem

there is two things that shut down the engine through the safety switches, 1 is it grounds the coil wires so it quiets firing the spark plugs, they are small flat spades on each of the coils under the flywheel shroud, unplugging the key switch should overcome that . The second thing is there is a wire that fastens to the bottom of the carb that opens a solenoid to allow fuel to the main jet, unplug it and put a jumper wire from the positive battery terminal to the wire on the carb and this will open it so it can run. Now touch the two big battery cable nuts on the starter solenoid together with a screw driver or metal pliers handles to turn the engine over and when it starts stop touching the terminal on the starter solenoid. To kill the engine unplug the hot wire to the fuel solenoid from the + battery terminal. If you can read wiring diagrams you can do this. Like you I want to hear it run before I put much time into it,

Charge the battery fully, verify good contact on the battery terminals. If it won't crank, check for voltage at the starter motor while trying to crank, check battery voltage while cranking (if it drops below 9V, the battery needs to be replaced).

If it cranks but doesn't fire, make sure it has plenty of good fresh gasoline, verify that the carburetor float valve isn't sticking shut, verify that the spark plug is good and you're getting good spark while you crank.

http://www.greenpartstore.com/assets/images/instructions/2012/am138497_installation_instructions.pdf

John Deere Starter Solenoid Kit AM138497

First make sure the negative battery cable is making good contact on the frame or what ever part of the mower it is connected to. Make sure both battery cables are clean and not corroded and are tight. Then try to start the mower. If it works, fine. If not then you will bypass the solenoid and see if the starter turns the engine. To bypass the solenoid take a car jumper cable and connect one clamp to the terminal on the solenoid that goes to the battery ( see the diagrams in the links above) Turn the ignition switch to the on position. Take the other end of the same color of the jumper cable (say you'll use the red clamps) and touch the clamp to the other large terminal on the solenoid, which goes to the starter. If the starter turns the engine, then you know the starter is good and that the solenoid is bad. If the starter does not turn the engine then the starter is bad. make sure you DO NOT touch the jumper cable to the starter case or any other ground.

was the piston replaced with the wrong one?locking up in the bore when hot?where the rings wrong as well take it apart and check the clearance before the bore is damaged

I had a similar problem lasy year.
Try this:
As soon as the machine seems to be stalling, loosen the gas cap.
If the engine continues to run, clean the gas cap vent hole(s).
Gary

If all of your tests are correct, the thing remaining is the ignition coil. A bit of a pain to get at and expensive too. Parts diagram here. Before you buy a new coil, see if there might be just a broken spark wire or loose connection at the spark plug contact end.

We will be testing for voltage to the points, coil, engine to tractor wiring harness, ignition switch

Tools needed:
volt meter to read 12 volts, or test light

1) with the points open: is there voltage at the connection wire at the points
If yes; adjust points to .020" and try to crank engine and check for spark
*** you may want to determine if condensor is connected to this wire also
if no
2) check point side (neg or - ) of coil for voltage
if yes, engine should start
if no
3) check for voltage at the + side of coil
If yes, coil is bad
if no
4) check wire connector from engine to frame wiring harness
if yes; engine should start

if no
5) check wiring on the back of ignition switch
if yes; engine should start

if no
6) check that ignition switch RED or BATTERY supply wire has voltage
if yes; switch is bad

if no
7) check supply wire and circuit breaker connected to the battery side of the solenoid
if yes; engine should start

if no; circuit breaker could be at fault or wire connector at battery supply

I’m happy to assist further over the phone at https://www.6ya.com/expert/rolandw_c013176d62ee17ae

Sounds more like a bad starter than a bad coil.

A failing coil usually shows up during hot weather. The engine will start and run fine, then when it heats up, it just dies out. After a few minutes, it cranks again. Then the cycle repeats itself.

The ignition module and coil pack are the same part.

Are you sure full voltage is getting to the starter? There is likely a starter solenoid between the ignition key and the starter. These solenoids can be problematic and prevent the full 12 volts from getting to the battery.

I usually fix electrical problems by process of elimination. Disconnect the wires attached to generator and touch the battery cable to the battery if it still arcs disconnect the regulator. continue until you find whats pulling current from the battery.