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Donald
Donald, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1797
Experience:  I have 25+ years of experience repairing 2 & 4 cycle engines
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Jon K. I have reviewed your response regarding"crank, no

Customer Question

Jon K. I have reviewed your response regarding"crank, no spark" presented on this forum. I have a Briggs and Stratton, Model 24A707 Type 1238-01. It's an 18HP Twin II.
It will NOT start. It cranks, no start, no spark. I followed your advice to someone else about removing that small wire (at coil) and having an assistant utilize the starting procedure as they try to start the mower. Still NO spark... cranks, but nothing.
Prior to this, I was having difficulty starting the mower. I disconnected the yellow wire (below the key ignition) and it started. I mowed for a while and touched the wire together to stop the mower. I purchased a new ignition switch (the clerk didn't look up part number, just matched the part) and installed it correctly. Since then, no start, it cranks, no spark. Today purchased a coil and installed it. Gap at .010 and same thing, it cranks, no spark, no start.
Any troubleshooting suggestions WILL be appreciated. Also, I did locate the manuals for the engine as well as the service manual for the mower. However, I'm NOT sure what direction to take. The mower is a MTD Yard Machine, if you need the model number, let me know and I'll provide it.
Thanks, ***** ***** for considering my question(s).
Submitted: 5 months ago.
Category: Small Engine
Expert:  Donald replied 5 months ago.

Hello. Thank you for choosing Just Answer. My name is***** will be happy to assist you. You have basically covered all of your bases. You set your gap at .010", and replaced your ignition coil. Keep in mind that only three things wire prevent your ignition coil from producing a spark to your spark plug.

  • The small black wire (kill Wire) at your coil.
  • The magnets on your flywheel being too weak.
  • Or if the ignition coil itself is faulty.
Expert:  Donald replied 5 months ago.

If you remove the small black wire from your ignition coil, and you still do not get a spark to your spark plug, either your ignition coil is at fault, or your flywheel magnets are too weak.

Expert:  Donald replied 5 months ago.

Did you notice any rust on your flywheel magnets?

Expert:  Donald replied 5 months ago.

If so, use some sandpaper, or a wire brush to clean the rust off. Also sand the two mounting surfaces, that your ignition coil mounts to. This will ensure a good ground for your ignition coil.

Expert:  Donald replied 5 months ago.

If you still do not get a spark, with the small wire removed, it is possible that your new ignition coil is faulty, although it is new.

Customer: replied 5 months ago.
I did notice a rust build up. I cleaned it off with a nylon brush. I was afraid to use sandpaper or a wire brush. What grade sandpaper should i use to clean that and the mounting surfaces?
Expert:  Donald replied 5 months ago.

A medium grit will do. Just sand it until the rust is removed.

Expert:  Donald replied 5 months ago.

After you finish cleaning the rust, check again for a spark. What method are you using to check for spark?

Customer: replied 5 months ago.
Ok, I'll give that a try; then when my husband gets up I'll have him try to start it as I check for a spark. It may be in the morning, however. He isn't feeling well today. The heat got to us already today. Method is a spark plug tester attached between the spark plug wire and the metal frame.
Customer: replied 5 months ago.
After I clean the rust off, should I apply a light spray with WD-40 around that edge?
Expert:  Donald replied 5 months ago.

Can you take a picture of your tester, and attach it to our discussion.

Expert:  Donald replied 5 months ago.

Just wipe your surfaces off with a rag. You will not need to add any lubricant.

Expert:  Donald replied 5 months ago.

You can use the WD-40 to cut remove the rust, but I would wipe it all off, afterwards.

Customer: replied 5 months ago.
Sure, I'll send you a picture as soon as it stops raining... It's storming right now. That's why I gave up and sent in a request for assistance.
Customer: replied 5 months ago.
Ok on the WD...
Expert:  Donald replied 5 months ago.

No problem. I understand. The reason I wanted to see your tester, is because most testers attaches to your spark plug wire, and to your spark plug.

Customer: replied 5 months ago.
My luck, I probably have the wrong thing... yesterday, my son used a screwdriver and he said no spark that way... Then I found my tester.
Expert:  Donald replied 5 months ago.

After the rain stops, we will figure it out.

Expert:  Donald replied 5 months ago.

Take your time. I will be here until 11:00 pm central time.

Customer: replied 5 months ago.
Since it's still raining some and my husband is feeling really bad this evening, I thought I'd send you a picture of the TYPE of tester I'm using and where I'm connecting the clamp at on the mower itself (yesterday I took pictures of the wires to help me identify which ones were which). I'm connecting the clamp to the bolt, next to the wires for the headlights, on the right hand side of the mower. I moved the clamp around today to make sure I had a good connection. I have the gap set at.030; because that's what the plugs are set at.
Expert:  Donald replied 5 months ago.

Thanks for the pictures. Take a look at your image below.

Customer: replied 5 months ago.
I went out and sanded on and around the magnets, around the flywheel, and the mounting brackets. I connected the tester as you indicated and still don't have a spark! Although I didn't have the best light to see everything I was doing...I do, however, know I the gap correct. In the morning, I'll try and clean the surfaces again. I don't know if you will be available over the weekend. If not, that's OK. Will you be able to respond when you get back online or will I have to start over with someone else? I'd rather keep working with you, if possible; because I've already outlined everything we've done up to now. Also, my husband is wondering if it could be a defective or wrong ignition (key) switch.... If so, how could we check or confirm that particular part?
Customer: replied 5 months ago.
I'm on Central Standard Time as well.
Expert:  Donald replied 5 months ago.

Good morning Sheila. You can try sanding everything again if you like. Just clean all sanded areas afterwards. If you leave the small black wire disconnected from your ignition coil, this will eliminate your safety switches, and your (key) switch, from preventing your ignition coil from producing a spark to your spark plug.

Expert:  Donald replied 5 months ago.

Have you recently replaced your (key) switch? If so, I can check for the correct part numbers for you. Keep in mind, that with your small black disconnected from your ignition coil, your (key) switch is ruled out, as a possible cause for our problem.

Expert:  Donald replied 5 months ago.

If you have another mower, or trimmer, use your tester to check for spark on that engine, just to confirm that your spark tester is actually working. If your tester is actually working, and you still are not seeing a spark on the engine you are working on, then you may have a faulty coil, although it is new.

Expert:  Donald replied 5 months ago.

We can continue from here. I will be here all day. If I do not respond to you immediately, it will be because I have stepped away from my computer. I will reply, as soon as I return. Thanks!

Customer: replied 5 months ago.
Good morning Donald. Yes, we recently replaced the key switch. However, when my husband went to purchase a new one, they didn't look up the part number; they just matched a switch up to the old one (which, he left there and they disposed of it in the trash)! Today, if I can find the package, I'll Google that particular part number (or send it to you) to see if it's correct or replaces the original part. Also, since it's NOT raining right now, I'm going to lightly sand any remaining rust from around the magnets and the brackets, wipe the dust residue off, and give it another try. I'll update you later today with my status or additional questions. Thanks so much for your rapid responses! Enjoy your day!
Expert:  Donald replied 5 months ago.

Very good! Keep me posted on your findings. Thanks!