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can't get my Husqvarna 55 Rancher to spark

Started by Megunticook, June 01, 2018, 08:33:48 AM

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Megunticook

I bought a new Husqvarna 55 Rancher back in 2004, has always run great and I take good care of it. Moderate use (cut 2-3 cords of firewood each winter).

A few weeks ago it quit on me while in use, stalled after it was warmed up and I'd been using it for 20 minutes or so. I checked everything over and finally determined there was no spark. So I replaced the ignitor with an OEM and still no spark. I thought maybe the ignitor was bad, so I replaced with another OEM--no spark. I have the gap set exactly to spec., 3mm. I replaced the spark plug but no dice. I disassembled the switch to see if that was bad but everything looked fine. I cleaned the flywheel where the magnets are--nothing.

What could I be missing here? I'm usually pretty handy with engines and mechanical stuff (maintain my own vehicles, etc.) but this has me stumped. Could the flywheel be bad? A new one is $100, don't really want to replace that just on a guess.

How is the ignitor grounded? The mounting surface is plastic, but maybe the mounting screws thread into the metal block? I'm at a complete loss.

What further tests should I be doing? I'm about to give in and drop it off at a shop, but I hate to let this thing get the best of me! It's a pretty simple design, I ought to be able to figure it out.

Any ideas appreciated--thanks.

Hilltop366

Not much left to check other than disconnecting the kill switch wire and removing plug cap to check for spark. The spark should jump ¼" in the air but the spark with "newer" higher voltage ignitions should be a little blue snap and is hard to see in daylight so I try to check in a darkened area.

The flywheel magnets should hold a screwdriver which some resistance to pull off. I have never had to replace one on any saw before.

Still no spark, can check (with ohm meter) for open circuit or short in the coil primary and secondary coil circuits and short between primary and secondary. Don't know the specs but try google / youtube for more info.

mike_belben

Is the flywheel to coil pickup gap too large?  Slide in a business card, rotate the magnets to align with the irons and loosen the screws on the coil then retighten and roll it over a few times to make sure they still clear.

Any ripped pinched melted or nibbles wires?  Maybe under the carb rubbed through or something? 
Praise The Lord

Skeans1

You said you stalled the saw every time I've done that I've sheared the flywheel key off, it's easy to check with an impact to remove the flywheel nut and a block with a hammer.

Megunticook

I checked the gap, set it to 3mm which is factory spec.

Ignition wire, boot, plug are all new. Tried removing the kill switch wire.

Don't believe the flywheel key is sheared--by stall I just meant that in the middle of a cut it slowed down and stopped pretty quickly. How would that shear off anything? And anyway it should still spark, right?

How is that coil grounded? That's the only thing I can think of that might be wrong--but where it mounts is plastic, so cleaning that wouldn't do anything...

dougand3

On a Husky 55 (or 50 or 51), the coil/ignition module mounts into the magnesium crankcase. So, if you're screwing into plastic, something is off. Maybe you have a Husky 455 Rancher. It has a weird shaped metal clip that connects a coil screw to the cylinder. 
Husky: 372xt, 272xp, 61, 55 (x3)...Poulan: 315, 4218 (x3), 2375, 2150, 2055, 2000 (x3)...Stihl 011AVT...Homelite XL...Saws come in broken, get fixed or parted, find new homes

joe_indi

Disconnect the switch wire at the ignition coil, it could be grounding somewhere.
A new plug need not always be a working plug. If you have any other equipment like another saw or a brushcutter or something use a working plug from one of those as a test plug.

Megunticook

Quote from: dougand3 on June 01, 2018, 06:44:39 PM
On a Husky 55 (or 50 or 51), the coil/ignition module mounts into the magnesium crankcase. So, if you're screwing into plastic, something is off. Maybe you have a Husky 455 Rancher. It has a weird shaped metal clip that connects a coil screw to the cylinder.
No, this is the 55 Rancher, not the 455. Here's a picture of where the coil mounts. The mounting screws thread into metal sleeves in the plastic. Are these somehow grounded to the case? Could that connection somehow be broken?


 

Megunticook

Quote from: joe_indi on June 04, 2018, 09:29:10 PM
Disconnect the switch wire at the ignition coil, it could be grounding somewhere.
A new plug need not always be a working plug. If you have any other equipment like another saw or a brushcutter or something use a working plug from one of those as a test plug.
I did disconnect the kill switch, also tried 2 different plugs.

Megunticook

Quote from: Skeans1 on June 01, 2018, 12:16:10 PM
You said you stalled the saw every time I've done that I've sheared the flywheel key off, it's easy to check with an impact to remove the flywheel nut and a block with a hammer.
If the key was sheared, it wouldn't be moving the piston when you turn the flywheel, right? Based on the resistance I feel when the spark plug is installed, I think the key is OK. But at this point maybe I should check anyway...I'm kind of at a loss here.

dougand3

In your pic, that's all metal. The coil screw hole will conduct to the cylinder. You can check with a multimeter - lead at coil screw hole wall and lead on cyl fin - probably 5 ohms or so. 
The flywheel key can shear just a few mm and flywheel seats back on the taper. It will still spark but spark timing will be real early - piston halfway up on compression stroke. The piston will move normally. All that said - that's not the issue here.
Sounds like the only thing left to be wrong is flywheel magnets. Never seen it but heard of them going bad or polarity change.
Husky: 372xt, 272xp, 61, 55 (x3)...Poulan: 315, 4218 (x3), 2375, 2150, 2055, 2000 (x3)...Stihl 011AVT...Homelite XL...Saws come in broken, get fixed or parted, find new homes

Hilltop366

Well if the coil is getting ground (test with ohm meter from coil laminates to cylinder).

Kill wire disconnected.

The coil gap is set correct.

The magnets still work.

Remove the plug cap and hold the wire ¼" or less away from the cylinder.

Pull the saw over fast enough.

Still no spark, you may have bought two bad coils.

realzed

Quote from: Hilltop366 on June 06, 2018, 05:19:36 PM
Well if the coil is getting ground (test with ohm meter from coil laminates to cylinder).

Kill wire disconnected.

The coil gap is set correct.

The magnets still work.

Remove the plug cap and hold the wire ¼" or less away from the cylinder.

Pull the saw over fast enough.

Still no spark, you may have bought two bad coils.
Is it possible that the spark plug wire is grounding somewhere and got abraded along the way to the point where it finally started arcing when you were mid-cut?  

Megunticook

I tested for continuity between the coil body and the cylinder head--it was fine.

Regapped the  coil again to 3mm. Put yet another new sparkplug in.  No spark.

The only thing left I can think of to do is replace the flywheel. The magnets still seem strong, but I don't know what else I can try at this point. Hate to spend $100 on a guess though.

Maybe it's time to cry uncle and take it to a shop. Strange though--seems like a pretty simple system, ought to be able to fix it myself.

decableguy2000

Maybe I miss read what your air gap is 3mm. It should be 0.3mm about the thickness a business card.

ladylake

Timberking B20  18000  hours +  Case75xt grapple + forks+8" snow bucket + dirt bucket   770 Oliver   Lots(too many) of chainsaws, Like the Echo saws and the Stihl and Husky     W5  Case loader   1  trailers  Wright sharpener     Suffolk  setter Volvo MCT125c skid loader

steele109

Hi I agree with decableguy2000 your air gap is too wide adjust it with a business card.All husqvarna 50-55 have a metal crankcase so grounding shouldn't be a problem.

Megunticook

I reset the air gap with a 3mm card that Husqvarna provides just to be sure it was exactly to specs. No change.

Either I got 2 bad brand new coils in a row (not very likely) or it has to be the flywheel.

Right?

dougand3

You can try an aftermarket coil for ~$10 online. Or a used coil & flywheel combo is $35. Check ebay.
Husky: 372xt, 272xp, 61, 55 (x3)...Poulan: 315, 4218 (x3), 2375, 2150, 2055, 2000 (x3)...Stihl 011AVT...Homelite XL...Saws come in broken, get fixed or parted, find new homes

Skeans1

Quote from: Megunticook on June 11, 2018, 07:07:12 AM
I reset the air gap with a 3mm card that Husqvarna provides just to be sure it was exactly to specs. No change.

Either I got 2 bad brand new coils in a row (not very likely) or it has to be the flywheel.

Right?
I've sheared a flywheel key well still able to turn the crankshaft, your shaft is a taper fit so it's possible to lose time we'll still being tight.

sawguy21

It will be out of time but being solid state ignition, not the old points and condenser, it will still spark. I am thinking the module is not grounded or the kill wire is rubbing somewhere.
old age and treachery will always overcome youth and enthusiasm

Skeans1

When this happened on my 395 I lost spark as well.

Megunticook

Not the kill switch/wiring because it wouldn't spark even when I disconnected it from the coil.

Not a bad ground because I tested with multimeter.

Spark plug wire is brand new (factory installed to coil).

Compression? Maybe, but why would it suddenly lose compression? I'll see if I can get a gauge and test.

I'll pull off the flywheel and see if anything looks odd there.



Ben Cut-wright

Quote from: Megunticook on June 14, 2018, 08:03:44 PM
Not the kill switch/wiring because it wouldn't spark even when I disconnected it from the coil.

Not a bad ground because I tested with multimeter.

Spark plug wire is brand new (factory installed to coil).

Compression? Maybe, but why would it suddenly lose compression? I'll see if I can get a gauge and test.

I'll pull off the flywheel and see if anything looks odd there.

Testing continuity with a multimeter only indicates circuit integrity, not the circuit's ability to conduct a load.  It is possible to obtain an OHM reading that is withing normal range with no load, but not sufficient to do work.

The picture of the coil mounting seems to show potential for a poor ground. A better method for load testing circuits is to load them with a test light bulb.  In the case of a unit with no battery this means hooking the test light lead to a positive battery terminal, provide a ground lead from the battery to a common metal ground on the saw, then touch the test light probe to the coil mounting.  The light should shine properly if the ground is good. 

Skeans1

Another quick way to check and see if there's anything at all is lick your fingers grab the plug touch the cylinder and pull the rope, better yet call a buddy.

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