My John Deere 325 won't won't start. Replaced the

I know this is going to be hard to believe but you have either dirty / loose or coroded cabels if you jump it from the car and it strarts then the only thing you are doing is appling power to the outside of the battery connection the inside is not making contact with the battery post clean with a wire brush do both poles apply a no corode paste tighten bolts snug they're made of lead and bend easily so don't over do it Good Luck Bruce depending on where you live you may want to greese up the snowblower too :-)

Check the battery cables first. Check that both ends are clean and have good contact and are tight. Make sure the battery you bought was fully charged. If it still only runs with jumpers on you have an electrical problem with the ignition or charging system. Some of the tests for these items need special tools if you wopuld like to try leave a comment and I'll get back to you with how to procede. Other wise you should take it to a repair shop. But the usual cause of this problem is the battery or cables. They need to be clean and tight. To clean contacts it is best to use a wire brush or sand paper.