What do i do - tractor will not start - pops after cranking?

ive got a tractor that was running fine, that then di not start, checked spark and looked fine, thought it was carb, tor it apart, seems ok. now its all back together - when i crank the engine, running a spark tester i see spark fine, nothing happens will not fire, i turn key to off and engine pops once or twice like it is caught then dies - is my spark just too weak? carb flooded the engine? where do i go from here

First check your plug wires, for proper firing order, then pull#1 plug, bring it up on the compression stroke, stop at top dead center, and check your timimg. It sounds like a timing problem. When asking for help identify the tractor-truck-ect, that will help us to help you!

New Autolight spark plugs and try again.

B414 wih a gas engine - had it going great, parked the next day it did not want to run, have been working on since. I would have thought timming but it was working great. can not see how it would have jumped out of time (timing gear) will check firing order, think its correct as i did not touch, what should the point gape be on this tractor? just replaced the coil to make sure spark is trong enough - no differnce - just puzzled. The plugs are getting lots of gas - maybe to much?

Dad's H was a real head scratcher, the small gears driving the points stripped, it popped an crackled, wouldn't run right.

--->Paul

May be bad gound or bad connection, bad battery. not enought current to fire the plugs.

Just a hunch, here, but check your key switch, for continuity. Lots of times, people hang all kinds of sh!t, from a key ring, puts pressure, on the switch, makes the contacts loose.

agree on the ignition switch.

I had a magneto that lit up a test light when
it fired, but an old magneto repairman said it
might not have enough power to fire a plug under
compression. I put in a new condenser and the
engine started and ran fine.

What happened to the Magman that once hung around yt? he was a good source for mag parts and info.

(quoted from post at 07:32:07 02/02/12) What happened to the Magman that once hung around yt? he was a good source for mag parts and info.

Click to expand...

Magman hangs out over on the cinderblock now.

The mag on my 42 H quit firing and between Magman and myself we gotter going. He even sent me all the parts before I paid for'em. He's a good honest man in my book..and he do know his mags..

run a jumper wire from the battery to dist . crank it and see if it will fire.dont leave jumper wire on though!!could be in your starting system.i fixed a ford this week that had a bad switch,owner had simply ran one wire from battery through a momentary switch,and then back to solenoid.it would crank wonderfully but he forgot switch gives a full 12 volts to ignition while cranking.If you have the same(and lots if not most do)it will start sometimes and others not depending on lots of times just a change in temperature,or weather,or wheather the engine is cold or not.A good indication of this is when it fires when you let off starter switch but engine is still turning.In that instant it gets full voltage to ignition.Which is what yours sounds like its doing.Sometimes it will go ahead and run,but if your battery is down from cranking it wont simply because voltage is too low until engine gets enough rpms to make alternator work.The same will happen "rarely" if you have a small battery in a vehicle with a large cranking load.It simply takes so much to crank it cant fire.this is why theres more than one size battery,or why some tractors have two batteries etc.

I believe some 12v tractors have a controller that increases ignition voltage
while cranking, then back it off once the engine is running. If you have one of those, that's most likely your problem. Don't remember what it's called, but we had a similar problem on a JD 2030 once.

the same basic concept can happen on a magneto.if the impulse quits it wont fire hot enough to start.simply because engine is not turning fast enough.to check impulse first just simply see if you can hear it.( it disengages when engine is running).Next check fire on each cyl.skipping cyls and firing on just one or two is a sure sign of a bad cap,rotor,dirty or misadjusted points(they HAVE to be set right, not close, in magneto and they HAVE to be clean). fire weak with a mag is quite often the condenser.Its possible you jumped time,easy enough to check by pulling no one plug.cranking engine over until you feel compression on hole and then seeing where dist or mag rotor is pointing.Hope this helps.

Do you have ballast resistor between the ignition switch and your coil? I would run a separate wire from your battery to your coil as been mentioned. That will bypass your ignition
switch. Don't keep it hooked up this way if it starts. Your switch may be defective. Make sure you have a good fully charged battery. Hal

Do not run a jump wire from battery to distributor. This will fry the points and melt the wire.
Jump to the coil on the side away from the distributor! Jim