Troubleshooting no spark

[THALL10326]

Hi. It is a fairly easy thing to check if you have access to either an ohm meter or a continuity tester. With a ohm meter, start by setting the resistance (R) scale to the lowest setting. (Example: RX1). If the meter has an auto ranging feature then don't worry about it, the meter will automatically do this for you. With a continuity tester you will have as an indication of a complete circuit either a light, an audible tone, or both together. I am assuming that your switch is attached to the metal housing of your saw. This would be your 2nd wire. With the switch stihl (sorry, I couldn't resist) attached, take one test lead and touch the terminal which has the wire hooked up to it. Take your other test lead and hold it against a clean and bare metal surface on the saw. As you cycle the switch on and off you will get a difference in readings or indications depending on what test device you are using. If there is no change then you have a defective switch or a grounded-out wire. It is actually very simple and it takes longer to read this than it does to do the actual test. Good luck.

Good post there. Real good one. You know your stuff...

 

[04ultra]

 

[THALL10326]

Damn ole boy your getting way to wise in your old age, good point on the tab. I never noticed it. Cheers for you my man.

 

[BlueRidgeMark]

One other thing I noticed...there was only one wire to the switch. ... Doesn't a switch need two wires to interrupt a circuit? I've got a black wire running to the switch as seen in the photo coming out of the points housing. What other wire should be running from the switch?

Well, it's been said, but just in case it isn't clear, the metal body of the saw is the 'other wire'. You are correct that you need a complete circuit, but in vehicles and other engines, the metal of the body is often used to carry electrical current. This is what is called 'ground'.

Think of a starter on a car. You have one heavy cable going to the starter, but none going back to the battery to complete the circuit. The current actually flows from the (+) battery terminal through the cable to the starter (via the solenoid, which is a switch), through the coils of the starter motor, and out through the starter body, through the engine body, through the engine ground wire to the frame, and through the frame ground back to the (-) battery terminal. (Sometimes the ground wire from the (-) battery terminal is connected to engine block directly.)

 

[THALL10326]

Well, it's been said, but just in case it isn't clear, the metal body of the saw is the 'other wire'. You are correct that you need a complete circuit, but in vehicles and other engines, the metal of the body is often used to carry electrical current. This is what is called 'ground'.

Think of a starter on a car. You have one heavy cable going to the starter, but none going back to the battery to complete the circuit. The current actually flows from the (+) battery terminal through the cable to the starter (via the solenoid, which is a switch), through the coils of the starter motor, and out through the starter body, through the engine body, through the engine ground wire to the frame, and through the frame ground back to the (-) battery terminal. (Sometimes the ground wire from the (-) battery terminal is connected to engine block directly.)

Good post Mark. You said it well. Knowing however your a computer buff too I'm going to be bugging you soon. Got my eye on a new Dell laptop and I need to know what all to get and what all to not get. So get ready for a zillion questions Mark, I'm coimg for ya..................

 

[josgmctk]

cleaning points

I am new to this site, you guys have lots of good info.
I do not want to be a pita, but sappy remove the bolt
that holds the blue and black wires, next remove the
blach screw and remove the points (two pieces) so
you can clamp in vise to hold and file the pits out of
contacts and then polish with 600 sand paper then clean
with electric cleaner ( do not touch contacts after cleaning
because the oil from fingers will cause the contacts to burn
quickly) my manual says point set at .020 in and
ign timing at 30 degres BTDC
by the way remember to install the ign cam on the crankshaft

 

[coveredinsap]

OK, some great information here, thanks. I understand about the switch now with the saw body grounding out the coil. I picked up a new switch the other day (same type, single pole) and installed that, so I'll test it as described, thanks.

The points are all cleaned up, and I set the gap using a business card:

Unfortunately it looks like the spark plug wire is integral, so I'm not going to be able to change that out easily.

 

[coveredinsap]

And after putting it back together the big Remington roars to life. Lord knows how long it has been silent. Man is this thing loud. I think I'll wait till tomorrow to adjust the carb, or the neighbors will be wanting to string me up.

Thanks again everyone for the help. You've risen an old Remington Super 754 from the grave.

I still need to clean/sand the rust off of the bar and get a new chain for it, but this baby is on its way to being a productive member of chainsaw society again.

Thanks

 

[retoocs555]

And after putting it back together the big Remington roars to life. Lord knows how long it has been silent. Man is this thing loud.

It does have a very distinctive sound. LOUD. Muffler, that's muffler?

 

[THALL10326]

And after putting it back together the big Remington roars to life. Lord knows how long it has been silent. Man is this thing loud. I think I'll wait till tomorrow to adjust the carb, or the neighbors will be wanting to string me up.

Thanks again everyone for the help. You've risen an old Remington Super 754 from the grave.

I still need to clean/sand the rust off of the bar and get a new chain for it, but this baby is on its way to being a productive member of chainsaw society again.

Thanks

Cool, sounds like job done. We had a few old Remmingtons in the family long ago and yes they are LOUD. Enjoy...............

 

[BlueRidgeMark]

But...........

.........electricity actually flows the opposite direction of what Mark has suggested and why wouldn't it!

Oh, don't get into a pissing match with an electrical engineer about electron flow vs. hole flow! :biggrinbounce2:

 

[BlueRidgeMark]

And after putting it back together the big Remington roars to life. Lord knows how long it has been silent.

Sweet! Man, that's gotta be a satisfying sound!

 

[CaseyForrest]

Congrats on getting that saw running Sap. I know I would have ditched it when I discovered Points ignition!!!

You are more tenacious then I!!

 

[THALL10326]

Oh, don't get into a pissing match with an electrical engineer about electron flow vs. hole flow! :biggrinbounce2:

Now Mark be nice, he didn't know you were a electrical engineer.:hmm3grin2orange: :hmm3grin2orange:

 

[RaisedByWolves]

Good Job Sap!


Dont fear points ignitions, they are your friend.

 

[coveredinsap]

Cleaned up the bar...boy was that a mess. Appears to be 24" original bar. Here it is waiting for a chain.

Thanks again for all the help.

Oh, the new switch doesn't shut the saw off. Go figure. Does it matter which terminal the wire is connected to? I wouldn't think it would. Anyways..there's one for the electrical engineers out there to ponder

 

[BlueRidgeMark]

Oh, the new switch doesn't shut the saw off. Go figure. Does it matter which terminal the wire is connected to?

It might. If you just bought a generic switch that fits, it might not be electrically the same. 'Twere it me, I'd take a meter and see where I had continuity. Test from terminal 1 to ground, with the switch in both positions, then from terminal 2 to ground, again in both positions, then from terminal 1 to terminal 2, again in both positions.

If your switch has two terminals, I would expect one makes connection to ground in one position, and the other makes connection when the switch is in the other position.

But some switches make connection between the terminals, and both terminals are isolated from ground. If THAT is what you have, it won't make any difference which terminal you use. NEITHER will work.

Keep in mind that I don’t know how this saw’s electrical system works, and I’m just assuming that your switch should ground through the body, based on your description and other’s comments.

But the first thing to do is get that meter or test light out and see how your new switch actually functions. And do yourself a favor - cheat. Make a list of the possbile connections and write down the result of each test AS YOU DO IT. Trust me on this - it's VERY easy to lose track of which combination did what. Since you have three possible connection points (two terminals plus the body of the switch) and two switch conditions, you have 6 possible conditions.

Something like this:

If your switch is a standard SPDT (Single Pole, Double Throw) switch, I think the above is what you'll find.

 

[BlueRidgeMark]

Oh, bother. Condition 2 should be Yes, and Condition 1 should be No.

Oh, well, it's just a quick illustration.

 

[coveredinsap]

The switch is a single pole, single throw toggle switch, Ace Hardware Medium Duty Toggle switch part #30747 rated for 15 amp, 120V AC or 10 amp, 240V AC

(it does have two contacts on it though, while the original had only one) Do I need to run a ground wire from the second contact to the saw's frame?

I'll run the tests you suggested and let you know what I find out.

Thanks

 

[Lakeside53]

yes, you do...