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I'm handy-ish, but don't normally work on engines, so forgive me if I explain things poorly. Here's the rundown.

If it matters, my mower's model number is 917.288280

Last week I noticed at the end of mowing that my mower sounded kinda rough. I shut it off and restarted it. It restarted fine but after about 2-3 seconds it sounded rough again. By rough I mean that it sounded like it was "missing/backfiring/sputtering." I was told that it could be a bad spark plug or a bad coil. I ordered a new set of plugs. Before just replacing the plugs I started the mower and pulled the coil wire off of the "driver's side" plug. All of the backfiring and missing went away. The engine was running smoothly. I shut it off and replaced that plug and attached the coil wire back onto that plug. I started it up and it was missing/backfiring again. I was told the next thing it could be is the coil for that side so I should order a new one and give that a check.

I was also told that while I wait, it wouldn't be any harm to mow the lawn. I was able to cut the grass the just fine. Most of the time I didn't even notice there was an issue. Every now and then it would feel like it was starting to run out of gas, then go back to being fine. When I stopped mowing, turned off the blades and parked it it was back to backfiring/sputtering pretty good.

So I have a few questions.

1. Am I getting good advice? Is this the road I should be going down?
2. When ordering a new coil, does brand, or the place I buy it from matters? I looked up the part number (691060) on Sears and it's about $48. It looks like I can order a new coil off Amazon anywhere from $15 to $30.
3. If I'm replacing the "driver's side" coil, should I go ahead and replace the other coil as well?

I have short videos of it missing and how it sounds with the coil unplugged if that will help.

Thank you for your help.

This is just my opinion, but before I would start replacing parts, I would do some more testing to see if I could nail down the cause. I’m not confident that the coil is your problem, because when you reattached the coil wire, problem returns, which to me says the coil is working. What happens when you disconnect the other side? Does the poor running change if you try choking the engine a little? I’m thinking you must rule out fuel problems before you proceed. Please supply us with the engine numbers so we can have a better picture of what you have.

Not real sure with this motor but can you swap coils from side to side? That would prove the coil issue. Might also try putting the choke on some when it starts sputtering, see if that smoothes it out, might point to carburetion rather than ignition.

I was going to check pulling the other coil just for the fun of it. I'll go ahead and do that now. I'll also check the choke idea.

What do you mean by engine numbers?

Ok. I pulled the coil wire off of the "passenger's side" plug and it smoothed out like pulling the driver's side did. I didn't swap the coils. I can do that if y'all think I need to.

I also experimented with the choke. This seemed to make a difference. When the choke was fully depressed (where it is when I normally run it) it was sputtering pretty good. When I pulled the choke almost to the point that it would start kicking out black smoke, it would run much smoothers with the occasional "quiet" sputter. The sort that I would associate with a v-twin and wouldn't have thought anything about.

So is this fuel related and not coil related? If so, what am I looking at doing?

ETA: Btw, thanks you two for being so quick with replies to help. Really appreciate it.

tluxtele said:

I was going to check pulling the other coil just for the fun of it. I'll go ahead and do that now. I'll also check the choke idea.

What do you mean by engine numbers?

Click to expand...

On mowers the engine is normally considered a separate item than the mower. If a Briggs Intek style engine the numbers will be stamped into the valve cover without the fuel pump above it. It a Briggs Vanguard it could be a metal tag either riveted to the blower housing or on a tag in the area of the oil filter. If a Kohler engine than there should be a sticker on the blower housing which may or may not be readable.

Pull a plug lead off and hold it approx 1/4" from the head and crank the engine. If you get a blue spark that jumps a 1/4" gap the coil is fine. Check both sides. If both coils pass you don't have a ignition problem. You have a fuel problem. Most likely you need to clean and rebuild the carb and see what happens. Any time you close the choke and it runs better you have a fuel problem.

Dealing with off and on rain because of the coming hurricane. I will check for the engine number and check both coils as you've suggested to rule them out.

Again, thank y'all. Very helpful forum.

ILENGINE said:

On mowers the engine is normally considered a separate item than the mower. If a Briggs Intek style engine the numbers will be stamped into the valve cover without the fuel pump above it. It a Briggs Vanguard it could be a metal tag either riveted to the blower housing or on a tag in the area of the oil filter. If a Kohler engine than there should be a sticker on the blower housing which may or may not be readable.

Click to expand...

Had a little break and went out for a quick look. Looks like it's a Briggs Intek. There were two numbers on the valve cover.
CODE 071005YG - was stamped into the valve cover.
445677 0827-E1 - looked to be on a sticker just above the stamped number.

Since you said stamped I'm thinking you want the first one, but here's both just in case.

tluxtele said:

Had a little break and went out for a quick look. Looks like it's a Briggs Intek. There were two numbers on the valve cover.
CODE 071005YG - was stamped into the valve cover.
445677 0827-E1 - looked to be on a sticker just above the stamped number.

Since you said stamped I'm thinking you want the first one, but here's both just in case.

Click to expand...

445677 0827-E1 is the engine model number
445677 is the engine number and im not really sure but i "think" the following numbers after it refer to variations of style differences and date it was built, but they are used to help identify the engine for finding the right parts

Model type trim code
445677 0827 E1 071005YG

The code is the date of manufacture in this case October 5 of 2007 and the last two letters are factory manufacture codes.

The model, type/trim are used for parts lookup and in some cases the code if more than one part was used with different dates. The word trim isn't normally stamps into the part. Normally just stamped with the words model, type and code similar to how I listed it at the beginning.

If this unit came in with this problem I would probably start by checking over the fuel system for air leaks. Things I would be looking for are leaking gaskets and cracked intake manifold. To check I would take my can of carb cleaner and with the engine running I would spray any area where the fuel would travel from the carb to the engine block. To do this you will need to remove the shroud to access the manifold. You can run the engine for a short period of time, at low speed, without worrying about over heating. If the engine speed changes you will have found an area where air is entering. If no changes then I would be looking at cleaning and rebuilding the carb. Note, these carbs are not the easiest for the DYI to do, so take a close look and this manual before you decide to tackle. https://docs.google.com/open?id=0B6NaqjIxWV1ySkZjTTA5TGltZEE

Rivets said:

If this unit came in with this problem I would probably start by checking over the fuel system for air leaks. Things I would be looking for are leaking gaskets and cracked intake manifold. To check I would take my can of carb cleaner and with the engine running I would spray any area where the fuel would travel from the carb to the engine block. To do this you will need to remove the shroud to access the manifold. You can run the engine for a short period of time, at low speed, without worrying about over heating. If the engine speed changes you will have found an area where air is entering. If no changes then I would be looking at cleaning and rebuilding the carb. Note, these carbs are not the easiest for the DYI to do, so take a close look and this manual before you decide to tackle. https://docs.google.com/open?id=0B6NaqjIxWV1ySkZjTTA5TGltZEE

Click to expand...

I'll check this when I get a chance as well.

I know this is a ways down the road... but let's say it's the carburetor. How long does it take for the average person to rebuild it? Aware of any good tutorials on youtube? I'm guessing the parts wouldn't be that expensive.
Now let's say I don't have the time to rebuild the carb myself. Would you suggest taking it somewhere (if so, where do I begin to look) or simply buying a new one? What would I be looking at cost wise?

U-tube, I have no ideas, as I very, very, seldom go there. Average person rebuild, if you’ve worked on carbs 1 1/2 hrs, if you’ve never worked on carb I suggest don’t even try. This will not be cheap, kit $90.00, labor minimum of 1 hour after the carb is off. Cost of carb approximately $200.00. I would suggest that you find a repair shop with the oldest, experienced mechanic in your area and have him troubleshoot the problem. Yes it can be expensive that way, but with this type of problem it may be cheaper in the long run. Remember here we can only give advice based on our experience and what you tell us. We are not standing next to you to experience the problem, so what we say could very easily be totally wrong and we could send you down a $$$$ path. Read my signature before you proceed

Similar to what Rivets has posted.
Being that your problem went away when you removed one of the kill wires suggests that the problem is in the wiring .
So if your mower has a carburettor solenoid, check that it is working
If so the remove the kill wires from both coils ad go mow
If the mower runs fine the kill wire is your problem
On some B & S twins there is a diode in the wire that connects the coils.
This prevents the coils interfearing with each other.
Search "Kill Diode" on this forum for detailed instructions for replacing it with a standard Radio Shack ( they still around ) diode or spending a bit more & getting the Briggs repair kit.