old 5HP B&S - new coil - still no spark?

[SC Maintenance]

My dad has an old B&S horizontal shaft on a tiller.

No spark - replaced the coil. The kill terminal is completely disconnected. Gapped it with a business card - no idea how thick the business card was. Still no spark. I don't know the coil brand. It was sourced from "the internet". (My dad is 85, and yes he still tills his own garden)

I told him to double check under the bolts of the coil, etc. I assume it grounds there?

So do the magneto coils on these things fail eventually - or try to source a better coil, or?

 

[2strokeNorthstar]

Depending on age there may be points behind the flywheel. The do fail sometimes

 

[SC Maintenance]

Depending on age there may be points behind the flywheel. The do fail sometimes

I would guess its 25 ish years old. I thought the trigger coil did that part?

 

[Lubener]

I have replaced several coils in the last ten years on various pieces of OPE which I have. I changed one last fall and it failed after three mowings. There are junk ones out there. I would atleast make sure you have continuity thru the coil, using an ohmeter. I would use a feeler gauge next time to gap it. Specs usually call for .008-.012. I go right in the middle. It is also warned not to over tighten the mounting bolts. A while ago, I ran into a flywheel which seemed to have a magnetic issue where it wouldn't trigger the coil but that is extremely rare. The ones I had did not have points.

 

[Lubener]

I would guess its 25 ish years old. I thought the trigger coil did that part?

You may just have to just lightly sand the points with emory cloth to restore the spark. Points last a long time and rarely go bad unless the condenser is open. I didn't realize it was so old with having points is a good possibility.That is very likely if the engine were stored with the points open. I always store an engine on it compression stroke where the points are closed and tarnishing rarely happens.

 

[mk378]

Electronic coils will not work if mounted on the engine upside down. Look for marks like "CYL SIDE" or "THIS SIDE OUT."

 

[fantastic]

My dad has an old B&S horizontal shaft on a tiller.

No spark - replaced the coil. The kill terminal is completely disconnected. Gapped it with a business card - no idea how thick the business card was. Still no spark. I don't know the coil brand. It was sourced from "the internet". (My dad is 85, and yes he still tills his own garden)

I told him to double check under the bolts of the coil, etc. I assume it grounds there?

So do the magneto coils on these things fail eventually - or try to source a better coil, or?

try sanding down the magnets a little where they contact the coil. The business card should be just fine. Replace spark plug & wire if you can. Otherwise it may even be an intake & exaust valve needing re-gapped. It gives you an opportunity to see if the valves are opening & closing too.

 

[Warstud]

My dad has an old B&S horizontal shaft on a tiller.

No spark - replaced the coil. The kill terminal is completely disconnected.

Did you try a new spark plug ? I always keep an extra one on hand .

 

[AndyB]

Last resort, check the flywheel key. If it is partially sheared, the timing for spark generation will be messed up. This would be for a magneto type ignition.

 

[SC Maintenance]

Did you try a new spark plug ? I always keep an extra one on hand .

I'll ask Dad when I call, but he likely did. Well, he would have 30 years ago. He is 85 so I'll ask.

 

[SC Maintenance]

You may just have to just lightly sand the points with emory cloth to restore the spark. Points last a long time and rarely go bad unless the condenser is open. I didn't realize it was so old with having points is a good possibility.That is very likely if the engine were stored with the points open. I always store an engine on it compression stroke where the points are closed and tarnishing rarely happens.

Is there an easy way to tell if it has points without pulling the flywheel. I looked on youtube and they said their were wires going behind the coil. Is the coil different? - I would presume the wires from the points and condenser connect to the trigger side of the coil?

 

[mk378]

The wire for the points would go from the coil to under the flywheel. It connects to the same terminal on the coil as the kill wire -- if an ignition kill switch is used. Many of the points engines were instead provided with a metal tab that grounds out the spark plug directly.

 

[Opelman]

I just had a Briggs 5hp on a tiller in. Verified no spark, turns out someone before me replaced the coil. Problem was that the low tension terminal on the new coil was touching the engine block. A little tweak to the terminal and problem solved.

 

[Radiotube]

If I may jump in on this old post, I have the same problem. I have a Honda FR700 rototiller with a G400 engine. It was running fine until it began to cough and backfire. This got continually worse until it wouldn't even start. I replaced the coil and made sure the points were clean. Still wouldn't start. Not even catching a little. I replaced the coil again. No change. I removed the points and put in a universal electronic ignition module in place of them. No change. I replaced the coil AGAIN. No change. The magnet seems like it's still strong. I don't know why it would have suddenly started failing and then never recovered. I'm stumped. There's not much to this engine to fail in making a spark. Because the coil and module are hidden behind the large flywheel, it's difficult to take measurements of these parts with a meter. Any ideas would be appreciated. It does seem like the magnet isn't inducing anything into the coil pickup.

 

[SC Maintenance]

If I may jump in on this old post, I have the same problem. I have a Honda FR700 rototiller with a G400 engine. It was running fine until it began to cough and backfire. This got continually worse until it wouldn't even start. I replaced the coil and made sure the points were clean. Still wouldn't start. Not even catching a little. I replaced the coil again. No change. I removed the points and put in a universal electronic ignition module in place of them. No change. I replaced the coil AGAIN. No change. The magnet seems like it's still strong. I don't know why it would have suddenly started failing and then never recovered. I'm stumped. There's not much to this engine to fail in making a spark. Because the coil and module are hidden behind the large flywheel, it's difficult to take measurements of these parts with a meter. Any ideas would be appreciated. It does seem like the magnet isn't inducing anything into the coil pickup.

What does the actual spark look like?

Have you tried starting fluid to see if it will even fire?

 

[Radiotube]

What does the actual spark look like?

Have you tried starting fluid to see if it will even fire?

There is no spark. I've tried starting fluid but I'm positive it's the spark that's missing. I've pulled the plug after several pulls and it's getting gas to the cylinder.

 

[mk378]

The G400 ignition is completely unlike a Briggs or other typical mower system. It has a two part older style system similar to a motorcycle. The exciter coil under the flywheel powers a separate CDI box. It is a solid-state no points system but it works differently.

 

[Radiotube]

This engine had old school points and coil with magnet on the flywheel. I think they made two versions of this engine. My shop manual mentions the CDI "supplement" but this definitely didn't have that. I wish it did, it would probably be running right now.