Ignition module question B&S 8HP

[docrocky]

Bought a Craftsman Rototiller that fits onto my Sears 15 few years back at farm consignment auction...realizing that few of us get rid of running equipment...but I am getting more comfortable with small B&S engines.

The first thing I did is test for spark, it turned over reasonably but no spark. I pulled off the recoil starter cover and as usual the magnet portion of the flywheel fairly rusty. Also the ignition coil had been changed by ?previous owner. Removed it without difficulty and did the usual wire brush cleaning of the flywheel and the coil pillars. I checked to see that there was one wire group grounded to the left pillar where the dust fin attaches to the coil and the kill switch wire was insulated. Turned engine over again and no spark. I then used the spark tester by Stens as well as older one used on larger engines which as a small lite bulb like a flashlight bulb. Still no spark via the tester light.

I then removed the spark plug and used the tester lights connected to the coil via sp wire and appropriately grounded it. With usual pull of recoil, get spark lighting the testor lamp but no spark passing thru the Spark plug. Tried two new plugs but still no spark passing, even with the finger feel test. I was very careful to gap the coil with the usual business card thickness but no success. I even tried metal gap setters starting with .020 down to .010 with same effect.

I then bought a new coil via e-bay thinking maybe some weakness in the coil was giving a week spark but not enough for the plug. Same result...great spark via the tester but still no spark. I even took off the flywheel to ensure the key had not slipped. I also remove what was left of the old points and condenser. Now I am not sure if the owner who replaced the coil for a newer version not requiring points and condenser ever got it started.

anybody have an owners manual indicating exactly what spark plug is needed. I assumed the one hooked to the engine was the right one, but who can tell. I currently am trying a champion J8C.

CRAFTSMAN ROTOTILLER
B&S 8hp
model; 190402
type 0780
code 74052210

Tiller
Model917251891 SN 1577

 

[tomplum]

Well,this assumes that you had the breaker set under the flywheel. If it has an external breaker box, it is a different ballgame. When you use the electronic coil pack you use only the one small wire to the coil which will ground to kill the engine. So no ground present at that wire to run. The rest of the old harness is not used. Do you also know if you have the electronic version of the coil? Part number would be helpful. I suppose that it is possible to get the point version, I dunno. Spark plug J8 is fine, J19 is fine. The little node light testers aren't much. You can practically pass gas and set off the light. It is many times possible to mount the coil backwards, which doesn't work out.

 

[docrocky]

Well,this assumes that you had the breaker set under the flywheel. If it has an external breaker box, it is a different ballgame. When you use the electronic coil pack you use only the one small wire to the coil which will ground to kill the engine. So no ground present at that wire to run. The rest of the old harness is not used. Do you also know if you have the electronic version of the coil? Part number would be helpful. I suppose that it is possible to get the point version, I dunno. Spark plug J8 is fine, J19 is fine. The little node light testers aren't much. You can practically pass gas and set off the light. It is many times possible to mount the coil backwards, which doesn't work out.

Thank You:
1.This is a very old machine because it did have a breaker set under the fly wheel. I decided to take down the entire flywheel to insure that the key way was in proper position which it was.
2.

 

[docrocky]

I must have hit a wrong key because it would not let me finis my initial reply.
2. I removed the breaker set cover and the original was still there, although rusted and it wires not contacting the newer coil present at initial inspection. I totally removed the remains and sealed it off.
3. The new coil packs come with 2 sets of wires exiting the coil. The first is not insulated and is to be connected to the (column) that goes over the fly wheel. The second wire is insulated and we understand it connects to the kill switch. We have totally insulated this off and use the small lever which ground the sparkplug to kill the engine.
4. I would assume that we have made all the correct connections and we are getting an electrical impulse which is verified by three different testers.
5. Why is the charge coming down from the new coil not sufficient to jump the spark plug gap, which we have as close as possible? We are not grounding out anywhere.
Thank You

 

[Barry 1]

Doesn't sound like the right coil.Solid State Coil only needs 1 wire for kill,and has a spade terminal to connect it to.They have a ground out of the coil,but it is attached to the coil leg.
But maybe it is right,can't tell with out a picture.

 

[docrocky]

Thanks Barry 1
1. Still confused...why am I getting a spark but it is so weak? I assume if wrong coil, would get no spark.
2. I notice when cleaning the magnet on the fly wheel, I used a small wire brush hooked to a small drill. I noted some metallic debris in the small grove surrounding the magnet. I used heavy air compressor air to clean it out plus small picks to get any jammed debris. When using a small magnet to get out any microscopic filings, I could never clean the cleaning magnet. I tried air, carb cleaner, electrical contact cleaner but a small little crescent is still visible. any hints.
3. Knowing "whats you pays for is whats you gets", as I ordered the coil as well as a replacement carb, no instructions came with either. I am not sure if there are ids for the parts. Purchased from e-bay and have done quite reasonably.

 

[Barry 1]

Have you tried to start it? Might be enough spark. Have you checked the valves? Did you check the spark pulling it over fast? Could be a weak magnet.

 

[docrocky]

Barry 1
1. Yes..have tried to start with either as well as fresh gas. no response.
2. Yes used a drill connected to the starting gear for faster rpm and still no spark combustion after pulling and pulling with the recoil starter.
3. Could it be a weak magnet on the flywheel the flywheel? How can it be checked or is what we are now doing the indirect test since we have ruled out the other possible caused. Are the magnets replaceable or are we in need of a replacement flywheel?
Have also tried new spark plugs X3.
Thank You

 

[Barry 1]

Just check the coil by feel when you set the clearance.( not easy to roll a business card between the coil and mag) I always had trouble with exhaust valve clearance getting too tight from wear and not enough comp. to start .You should pull the breather off and make sure you don't have a valve held open . Not much available for large parts,some used on ebay.

 

[tomplum]

So if you have a coil that has two small wires, that is used with the breakers. With it whiring around and you momentarily ground the breaker wire , it will release the spark. In an electronic ignition coil, the CD releases the spark. Part number of the coil could help wonders. Or skip the whole thing and put a Predator engine on it from Horrible Freight.