MF 50 No Spark

[SaveMy50]

MF 50 Gas w/ Alternator - tractor was shutting down after 10-15 minutes operation, figured coil (since it was really old), so replaced, along with new points, condenser, rotor, cap, but now I can't get it started. I have power (> 13v) to the coil, but no spark at plugs or even points (with cap/dust cover off)?

 

[SaveMy50]

Follow up: coil shows resistance between +/- pole and much higher between + and center plug. Made sure continuity from Negative side coil thru to points connection inside distributor. Was checking for spark on #1 plug, nothing for 30 seconds then spark, so I connected and it started. But it only ran 2 minutes before it shutdown. Sounded more like an electrical connection, as gas feed seemed fine. But coil seemed pretty hot for that short running. As noted, its a new coil?

 

[Jim.ME]

Follow up: coil shows resistance between +/- pole and much higher between + and center plug. Made sure continuity from Negative side coil thru to points connection inside distributor. Was checking for spark on #1 plug, nothing for 30 seconds then spark, so I connected and it started. But it only ran 2 minutes before it shutdown. Sounded more like an electrical connection, as gas feed seemed fine. But coil seemed pretty hot for that short running. As noted, its a new coil?

Did you clean the new points by rubbing a piece of brown paper bag, a piece of uncoated card stock or even a folded-up dollar bill between the point contact after you set them?

If you ground a test light lead on the engine and hold the probe on the coil terminal, that has the wire going to the distributor, does it flash on and off as the engine is being cranked over with the starter?

How did you determine the "gas feed seemed fine"?

 

[old]

Follow up: coil shows resistance between +/- pole and much higher between + and center plug. Made sure continuity from Negative side coil thru to points connection inside distributor. Was checking for spark on #1 plug, nothing for 30 seconds then spark, so I connected and it started. But it only ran 2 minutes before it shutdown. Sounded more like an electrical connection, as gas feed seemed fine. But coil seemed pretty hot for that short running. As noted, its a new coil?

New coil means nothing plus did you buy a 6 volt coil or did you get a true 12 volt coil. If it is 6 volts it will get hot fast and burn out fast with out a ballast resister in the circuit

 

[SaveMy50]

I did not clean the new points, will do that. I will try test light on the (-) of coil to distributor. I will test drain fuel again at the carb. I will get the coil type I installed confirmed.

 

[Jim.ME]

I did not clean the new points, will do that. I will try test light on the (-) of coil to distributor. I will test drain fuel again at the carb. I will get the coil type I installed confirmed.

You time how long it takes to fill a pint container. Do not count the initial gush of fuel you get when you remove the drain plug. You want just to catch the actual flow that occurs after that.

 

[SaveMy50]

So cleaned points with $ bill, Confirmed it was a new A&I Products A-21A513 coil, listed as 12V with internal resistor, at least as shown on package container, But still no spark even though 12.5V to the coil (+). I will bring a test light next time. Also still to confirm fuel flow, but spark plug was fuel soaked when I pulled it after trying to start for a bit. But I did find my condenser bolt appears stripped, so will replace and ensure a tight connection of P & C to coil (-) through the insulated distributor casing (even though I show continuity).

 

[old]

So cleaned points with $ bill, Confirmed it was a new A&I Products A-21A513 coil, listed as 12V with internal resistor, at least as shown on package container, But still no spark even though 12.5V to the coil (+). I will bring a test light next time. Also still to confirm fuel flow, but spark plug was fuel soaked when I pulled it after trying to start for a bit. But I did find my condenser bolt appears stripped, so will replace and ensure a tight connection of P & C to coil (-) through the insulated distributor casing (even though I show continuity).

One of the best and very simple test devices I keep around is a simple piece of wire. Hot the wire from the ignition side of the battery and then touch the ignition side of the coil on and off with the points closed. Watch for a small spark. No spark then the points are not conducting power so need more cleaning. If you get a spark when you do that pull the center wire from the cap and hod it close to the block and touch the wire back to the coil on and off you should have a spark at the coil wire.

 

[miner09]

If you’re getting fire to the points and not to the plugs then the ground cable needs to be cleaned where it mounts to frame etc. You can test by using ground jumper cable from battery to frame. Make good connections.

 

[SaveMy50]

Now cannot get a resistance continuity across the coil + & -, so appears have to replace. Why might this new coil only run the tractor for 2 minutes (as noted above)? Work in progress ....

 

[SaveMy50]

Solved, I think, replaced condenser stud that stripped (not fully tightened) inside distributor, then replaced coil with an oil filled one previously bought (and lost in shed, but that I could measure continuity across +/- connectors and across +/center wire hole), then found all spark plug wires failed (could not get continuity), so used ( and taped up) an old set that are damaged but measured continuity, connected all and it started up in 2 seconds But doesn't fully explain how whole system can fail like that? Ran for 5 minutes only for now, will get a longer test once its not 95 degrees out there. I will replace spark plug wires.