What's up everyone? Welcome back to The Durbin
Compound! If you haven't met me already, my name is Devin Durbin. So today on the channel what
we're going to be doing is troubleshooting a trimmer that just won't start. So this is a 2013
model Stihl 100 RX. I've had it since then. I haven't put any hours on it. I have another 100
RX that I used mainly. This is a backup trimmer. From time to time, I will run this, but it has less
than four hours on it. It is springtime--ready to fire it up and get it going for the season and
guess what? It won't start. So for some reason it won't start. Today we're going to troubleshoot
it and figure out exactly what it is. If you're interested in what I have to say about it and
going forward and troubleshooting it stay tuned. {music playing} All right guys, so first things first, when it comes
to small engines there's two things that you need is fuel and spark. Some people might argue
that you need air as well. That is true, but the only thing that's going to restrict airflow is a
clogged air filter. So this one's brand-new. So we really don't have to worry about that. What we're
going to do here is, you know, I stored this with fuel in it this season, or this winter, and it really
doesn't smell like bad fuel. I keep STA-BIL in my fuel. I keep my fuel stabilized and I
think this might even be MotoMix that's in here. So I'm not really worried about the gas going
bad, or have gone bad, since I ran this last. So what I'm really concerned about here is spark. I'm
going to chase the spark first. I do not think it's a fuel problem. What we could do, is we could spray
some starting fluid in it and see if it fires. But it's easier just to pull the plug out real
quick and see if we have a spark. There's a plastic guard on this carburetor and I could
take that off and I could spray starting fluid in it. That's what I'd probably recommend, most
people that are trying to get a trimmer running is, just take some starting fluid and spray it in
the carburetor. If it fires off, then you know that you have a fuel problem and not a spark problem.
I have a reasonable assurance that this is good gas. So I'm going to go ahead and say that this
is probably a spark issue. So what I want to do here is, let's take off this spark plug. It is a
little R10. So it's probably going to be 5/8". So using my Tekton tool set--love it. All right, so
first things first, let's test the spark on this bad boy here. We've got it out. It is wet. So, the
first thing to look for if you're taking the fart, the spark plug off... the fart plug I said. The spark
plug--you see how it's wet from fuel? It is getting fuel into the cylinder. So, I bet that this isn't
going to have any spark. So go ahead and insert it back into the spark plug plug here. What we're going to
do is make sure that it's grounded to the engine somewhere here. And we're going to pull the recoil
to see if it does spark. So, let's check it out. All right, it definitely does not have spark.
So we're going to put it down on something here. Okay, so now let's rule out a bad spark plug. So, I
don't think I have an R10, but I probably have a BPR7A. Let's take out another spark plug here
and just test this to see if this will fix our issue here. If it does, then we just get a new
spark plug. The fact that it's wet definitely makes it apparent that I am getting fuel,
just not having a spark here. Okay, so something is keeping our coil from firing. So what we might
want to do here is figure out just what's going on here. Maybe it's grounding out. One thing I can
do here is probably disconnect the coil from... I might be able to disconnect the coil. Basically what this will do is take out the switch. All right, so I'll try to show this a little better
here. So, you might want to check this micro switch here. If it's in the stopped position, it will depress this. Basically making the circuit complete. All right, so I just wanted
to make sure that our handle here was not depressing. See this is pushed forward, all the
way to stop, is where it depresses the switch. And then it comes off. All right, so when I initially
took these off, I was correct. So if I did take this off, or when I took these
off, it would basically keep anything in this circuit here from grounding out the coil and not
working. So, basically what happens here is a wire that is completed with that micro switch,
once that micro switch depresses, the continuity is made back in this circuit, and grounds it out
here at this screw. So taking these clips off would do precisely what I was saying, by allowing the
coil to work if the switch was depressed. So if the trimmer was in the off position,
then taking this off would allow this to fire on its own. So I think what we have here is
a problem with the coil. So what we're going to do is, I'm going to take this coil to the saw
shop and I'm going to have them test it. So I need to finagle the coil out of here enough to
be able to take it and get it tested. Just have it tested by the Stihl shop and figure out if
it's bad or not. It won't fire a brand new plug. It might be too big of a plug for it. It might not
be. I don't know. I don't have a plug this small. So what I'll probably do at the shop is pick up
a new spark plug and get the coil tested and we'll continue the video after that. All right guys, so we're back the next day here. I had to replace the coil because I took it to the shop
and they could not get a spark out of it. So the old coil was bad. I did get it confirmed that it
literally will pretty much spark any spark plugs. So us testing the spark plug with a different--with
the BPR7A, or the BPMR7A, it would have made spark if it was good. So, we ruled it that
it was bad before we even took it there. So, what we're going to do is put this bad boy back on here. And
then we're going to go ahead and make sure that it is gapped correctly. So the easiest way
to do this is with a business card. I'll show you here shortly here. Let's get this thing close.
Going to...get this close here. All right, I'm going to put this other bolt in here. Okay. All right. All right, so we get close to snug here. All right, now just a regular old business card. Go ahead and slip it...we want to turn our flywheel
around until the magnet part is facing the coil. See the magnets here? I'm going to make sure
that this business card is in between here, and turn them over to where they're at. All right,
so that business card separates the coil and the magnets. We'll go ahead and tighten it up.
That is the easiest way to make it happen. So make sure these are nice and snug and they're
not going to go anywhere. That business card allows us proper clearance, Clarence. And go
ahead and take that out. And it should make spark here. So let's go ahead. I also bought a
new plug because the other one was suspect. So, if you're looking for a different plug the NGK plug number is 7599 or CMR, yah, CMR5H. I'm going to go ahead and put this back
in here. All right, so we should see a spark now. All right! We have spark! Sweet! Probably hard to
see on camera, but we have spark. I'm going to go ahead and put this in. I'm going to tighten it down.
And then I'm going to go ahead and put the trimmer back together on a time lapse here and we'll go
ahead and fire it up. All right, so always remember when working on small engines that air, fuel, and
spark. So, we got some spark when we had it apart. So we're going to go ahead and give it a shot. Start
this bad boy up and see what it does. {sound of trimmer starting and engine revving up} All right guys, so not the perfect video, but definitely a
real-time troubleshooting a trimmer that doesn't start. I got the coil replaced and got it going. So
I'll need to put another tank of fuel through it. Get it running very well. Get all of, maybe the
fuel that was gummed up in it. If you left it for a year or two years, you're going to have more
problems. So, I hope this helps somebody. Give me a thumbs up. Or a thumbs down. Whatever you're into.
And I guess we'll see you guys in the next video.
