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.

 

[docrocky]

tomplum

I an darn close to the Predator suggestion.
1 item sold by theropshop 1 item sold by theropshop






IGNITION COIL MODULE MAGNETO for Briggs & Stratton 7hp through 16hp Lawn Mower


IGNITION COIL MODULE MAGNETO for Briggs & Stratton 7hp through 16hp Lawn Mower
( 271677229339







IGNITION COIL MODULE MAGNETO for Briggs & Stratton 7hp through 16hp Lawn Mower


IGNITION COIL MODULE MAGNETO for Briggs & Stratton 7hp through 16hp Lawn Mower
( 271677229339

 

[docrocky]

[tried to send picture but not smart enough to get it to paste.

 

[Barry 1]

[tried to send picture but not smart enough to get it to paste.

You have to use points with that coil.Or buy a magnetron conversion if you can find one.
Jacks Small Engines has a Solid State Coil #440417 that fits you motor for $ 39.15

 

[Barry 1]

Solid State Module Ignition Coil Briggs & Stratton 7-16 HP Enignes 398811 395326 $ 22.98
This one on Ebay should be the right one too

 

[docrocky]

Barry 1:
Thank you so heartedly for your information. I ordered what you recommended above yesterday and await its arrival. I will let you know immediately how it works out. I am repeatedly reminded how user friendly this forum has been to me in the past as well as the present. I am a retired surgeon and garden a 1.5 to 2 acre garden and all the produce goes to church kitchens, food banks and neighbors. I used to use a walk behind rototiller to control grass/weeds but since turning 80+ I have slowed down and I really need the Sears tiller attached to a nice Sears Suburban 15 I got a few years back. I also have a Cub Cadet 124 with its model 1 tiller attached but wasted a lot of time trying to convert to its creeper gear but it kept slipping out. Most all of the work is used to cultivate grass and weeds between the crop rows, other than corn.
Thanks Again

 

[docrocky]

Barry 1: I got the coil you recommended from E-bay and installed it today. Sadly, I get the spark on the test light but do not get the spark on the plug. I reved up the flywheel with a drill but not difference. I very carefully set the gap with a business card, index card, metal gap setters both at .010 as well as .020. I made sure that the kill spark tab is not in contact with anything and the coil is oriented to the outside as directed. I also tried different new plugs and set their gap as close as possible to .025 but no spark jumping the gap. At present my question is: could the magnet on the flywheel be too weak or worn. I also note that when I set the gap over the magnet part of the flywheel, when I hand rotate the wheel, it seems that the coil columns almost come into contact with the non magnet part of the flywheel. Do flywheels deform or warp?? Talking to several shade tree mechanic buddies of mine, that have never encountered a "bad" magnet. I will rummage in the junk pile for a B&S flywheel of similar design and give it a try.
Any other suggestions other than the Harbor F. Preditor replacement .I have a small Honda ?6 hp, would it be worth a try?

Thanks Again

 

[docrocky]

Gentlemen: Finally the answer to my dilemma...As I set the coil over and over again using business card, index card, .010, and .020 as I would manually turn the flywheel, it seemed to "wobble". The shaft that the flywheel attaches to is slightly tapered and a few steps back I noted that the key way pin was horizontally sheared and I obviously had to replace it. 3/16 I believe. I noted some difficulty when the flywheel was pressed back onto the tapered shaft. The key way seemed to climb up the taper of the shaft. With all this I really took the time to hammer the flywheel onto the shaft and I seemed to improve the balance and there did not seem to be any wobble. Putting all the components back together and using an index card to set the gap between the coil and the magnet...bam...I finally got spark to the spark plug and the engine immediately started after wards. What a learning experience and again I wish to thank those who offered advice. Tractor by net has been a very helpful forum to a rank amateur like me.