Ignition help please.

Subject is a MF135 3 cyl gas perkins. No spark. I replaced the coil cap wires plugs condenser points and rotor arm. Coil gets power and I even tried a second coil in case I bought a bad one. I put a timing light on coil wire and it didn't light up.... so I suppose the coil isn't discharging. What should I look at next?

Tractor stopped running on me and that's when I decided to do overhaul on ignition system. So it didn't run prior to all my swaps. Prior it would run for a while and then shut off... I sorta thought it was a fuel issue and rebuilt the carb. But no spark is a clear problem.....

Try cleaning your new points. Sometimes coating on points will prevent good contact.

Do some basic ignition troubleshooting.

You'll need a 12v test light or an analog volt meter.

Ground the test light lead or the black volt meter lead. Touch the positive battery post to be sure the light/meter is working.

Turn the ignition switch on.

You should have power to the + terminal of the coil. If no, check the wiring, ign switch, ballast resistor if equipped.

If yes, move the test light/meter to the - side of the coil. Crank the engine through and watch the light/meter.

If the light flashes, or the meter jumps every time the points open, it should be making spark at the coil tower.

If the light stays on, or the meter stays at 9-12 volts, the points are not making contact, there is a break in the wire from the coil to the points, or the distributor housing is not grounded. The housing grounds through the hold down clamp, be sure it is tight and on bare metal.

If the light does not come on, the points are not opening, the wire is shorted to ground, or the condenser is shorted internally to ground. It could also be an open coil, but you already tried a coil, so not likely. (Be sure to put the original coil back on, or be sure the coil that is on it is correct.)

Look carefully at the points and the installation. Try another condenser. All the ignition components are now imported aftermarket and very questionable quality, often bad new out of the box, or miss boxed. Check for side play in the distributor shaft. If loose, the points will not stay set.

Try this and let us know...

When you say put the tester on the side of the coil, do you mean across the two low voltage points? That would make sense and I hadn't thought of it.

I already did test power to the coil so I'm good to that point. I had tried putting a timing light around the coil output and didn't get anything, but it sounds like maybe I have a bad ground somewhere. I had tried a 2nd condenser as I too have doubts about new parts not always being so great.

If the test light on the neg side of coil is always on when cranking would that imply a bad ground or condenser or something else? Getting the same condition w two different new coils.

The answer to your question is in the post Steve@Advance made to you earlier.

(quoted from post at 16:05:09 03/24/19) If the test light on the neg side of coil is always on when cranking would that imply a bad ground or condenser or something else? Getting the same condition w two different new coils.

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Steve has you heading in the right direction with his instruction.

All I can add would be for you to pull the cap off and observe the rotor while someone turns over the engine for you.

Although you likely are dealing with an electrical issue it will not take you very long to verify that the distributor shaft is turning.

A chewed up gear, sheared roll pin, broken camshaft, timing chain or gear etc while not as common of a problem do happen and could cause the symptoms you are describing.

The ice thing about the 135 is you can easily reach the key while sitting on the front wheel. Mechanically things seem in good order.

For anyone following or finding in the future.... I think my issue is voltage drop from the batter to the coil. I'm going to be getting a new harness and think that might work. Everything else has seemed okay, but going from the test light to the volt meter showed how little power was getting to the coil....

(quoted from post at 16:42:48 03/25/19) For anyone following or finding in the future.... I think my issue is voltage drop from the batter to the coil. I'm going to be getting a new harness and think that might work. Everything else has seemed okay, but going from the test light to the volt meter showed how little power was getting to the coil....

Click to expand...

Check the voltage drop across your ignition switch if you didn't do that. If the switch is bad that will remain, unless you plan on changing it as part of the harness

I got spark... not enough to get it running after sitting for a year without any starter fluid though. There was a wire from the switch to the voltage regulator that was pretty melted, and the hot wire leading to the switch was down to it's last few strands... I repaired both sections and got spark. Battery is charging now and I'll take it back to the field tomorrow on my day off, but it seems to be good now!