Cranks But Won't Start

K-Mo

Member
Lessons Learned--
Yesterday I went to the machine, shed cranked up the little Mustang 310 skid loader to move some wheel weights. Shut it off and loaded the weights. When I tried to start it again, it cranked right over, but no fire. Tried to prime with some gas, no go. Pulled the spark plug to check for spark. Had nice blue spark. No reason not to run, but wouldn't even pop.
Although the starter spun the engine just fine, I checked battery voltage. Only about 12 volts. Charged battery to full charge. Hit the switch and fire right up.
Conclusion-- While cranking, not enough voltage on the coil to get a spark. Of course when I checked for spark, I had removed the spark plug. With the plug removed, no compression less load on the battery, and the coil received enough voltage to show a nice blue spark. Wasted a couple of hours when all I had to do was charge the battery.
Other similar experiences with Cub 154 and Farmall 140. After sitting over the winter, the 154 engine would spin, but no fire. Put a charger on for 5 minutes and it fires right up. On the Farmall 140, it was the ignition resistor. It would normally start with no problem. From time to time, the engine would spin, but not fire. Found too much voltage dropped by the ignition resistor. It had a 1.8 Ohm and I replaced it with a 1.4 Ohm. Works great ever since. 1.4 to 1.8 doesn't sound like much, but the difference in resistance is an increase of about 30%.
From now on to save time, I'm going to check battery voltage at the coil.
K-Mo
 
Just my opinion but a couple of stubborn machine I have just LOVE NGK sparkplugs. Give them a try.
 

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