OLD husqvarna rancher 50 not starting - seems to have spark, compression, fuel, timing?

[Chevboy0167]

Did you order a new OEM Husqvarna coil or aftermarket? I have a Rancher 55 do the same thing.. strong blue spark with plug grounded outside of the cylinder. Not a single pop even with a new plug installed. Pulled the recoil to find a new china junk aftermarket coil.

I got a used OEM Husky off of ebay, installed with a gap of a business card and it fired and ran perfect on the 2nd pull.

 

[jff]

thanks. I got an OEM part (or, at least, it said OEM). Triple-checked the flywheel, there's nothing to adjust so I'm not sure how it would get out of time. It must be the spark. I bought the spark tester recommended, I don't see a spark, which makes sense, but I also don't really know how to work this tester so it's hard for me to know whether there's no spark or whether I'm using it wrong. Am I correct in understanding that I would set the gap on the tester to SE (small engine) and ground the clip, and plug the terminal end into the plug boot? And I should see a spark inside of the tester? Thanks!!

 

[lone wolf]

hi all, just reporting back. Timing looks good, bought a new coil and getting a very strong spark outside of engine now but still not even a pop with gas right down in the chamber. I haven't gotten the spark tester yet but it's supposed to come today. I'm very confused. Only thing I can think of is maybe my compression isn't as good as I think it is? But it got up to 150+ with maybe 3-4 pulls, that seems good to me! First pull was over 100 and that's with the throttle off.

Anything else I should be checking until the spark tester gets here?

thanks

Flywheel magnets, possibly weak.

 

[jff]

Flywheel magnets, possibly weak.

Thanks. How do I test this? There is definitely magnetism, when I loosen the coil it zips over to the flywheel. But I guess I can't tell how strong the magnets are supposed to be. Is there some accepted test to see whether they're strong enough? thanks

 

[lone wolf]

Thanks. How do I test this? There is definitely magnetism, when I loosen the coil it zips over to the flywheel. But I guess I can't tell how strong the magnets are supposed to be. Is there some accepted test to see whether they're strong enough? thanks

Swap it with a known runner is the best way. Pull that muffler and see if the piston is all scored to hell first.

 

[Tony Mayhew]

hi all, just reporting back. Timing looks good, bought a new coil and getting a very strong spark outside of engine now but still not even a pop with gas right down in the chamber. I haven't gotten the spark tester yet but it's supposed to come today. I'm very confused. Only thing I can think of is maybe my compression isn't as good as I think it is? But it got up to 150+ with maybe 3-4 pulls, that seems good to me! First pull was over 100 and that's with the throttle off.

Anything else I should be checking until the spark tester gets here?

thanks

I don't even use a compression tester for the false readings that can accure if you have any carbon build up in the top of a cylinder! The best way to check a piston is to remove the exaust pipe and look up inside the exhaust port at the piston to see if it has any signs of damage. I take something that won't damage or scratch the piston and I push on the ring or rings to see if they are freely moving. Alot of times you will find that someone has either used a low budget oil or allows it to idle for long periods of time it loads the ring land behind the ring full of sticky oil and sticks the ring! I have tried all kinds of different methods to clean it out and only one thing will work, and that is to remove the cylinder and then remove the ring or rings! You can take something that fits in the ring land and scrap it clean. When I have to take it apart this far it usually is a hard to find chainsaw or something pretty special. I have a Husqvarna 61 300th anniversary edition chainsaw i have on the bench right now for that reason! But where are you going to find another special interest saw like that? You are forced to take it apart and make it run again, because it eats you alive when you have a chainsaw like that and you know how to take it apart and make it run again but you just keep walking by it and seeing it in pieces in a milk crate! You consciously tell yourself don't be that guy that says that he will get to it one of these days! Life is short, I own 135 chainsaws and it is fun to have the badest chainsaw besides arborist and loggers who always carry a hot saw with them!

 

[dboyd351]

Is this an old white top 50 Rancher with the sliding switch on top of the airbox for a choke mechanism? Weirdest choke I have ever seen. I don't really trust it even though mine works fine.
Might want to remove the cover and block the carb venturi with your thumb or something to choke it.
Good luck. Mine is a really good running older saw. I like it.

 

[jff]

Is this an old white top 50 Rancher with the sliding switch on top of the airbox for a choke mechanism? Weirdest choke I have ever seen. I don't really trust it even though mine works fine.
Might want to remove the cover and block the carb venturi with your thumb or something to choke it.
Good luck. Mine is a really good running older saw. I like it.

Thanks, yes, it's a white top with the sliding choke. I don't love the choke either, I have the top off and some rags shoved in the throat as a choke for now. Works a little too well, after 5-6 pulls with the plug out, actual non-atomized gas starts splashing out

 

[jff]

Just following up. I have my spark tester set like this (photo below) and I'm not getting a spark even with the plug out, and.... I'm guessing I should be getting a spark. New coil, checked the piston and it looks pretty good... I think it's time to replace the next most likely culprit. Would that be the flywheel?

However. I checked ebay, and all of the husqvarna 50 flywheels seem to have two key slots. Mine has one. Am I just not finding the right ones, or do I maybe have the wrong flywheel? Mine is an old white top rancher 50. Is that the same thing as a Husqvarna 50? Or how would I find the right flywheel?

Thanks!!

 

[dboyd351]

try that spark plug tester on something that you know has spark so you know you have the tester set right and it is working

defective coil/grounding is far more likely than weak flywheel magnets in my experience Yes I know you put in a new coil but you need to know you have a working tester before throwing more parts at it

 

[muddy42]

I have the same saw. This seems like a really tricky one!

Have you triple checked all the wires for breaks? try bypassing the kill switch? Are all the wiring contact points, spark plug coil thing and magnets definitely clean? Have you tried setting the induction coil lightly closer to the flywheel (use a thinner business card).

If all that is OK, I'd take the cylinder apart and check the piston and skirt tolerances.

 

[jff]

try that spark plug tester on something that you know has spark so you know you have the tester set right and it is working

defective coil/grounding is far more likely than weak flywheel magnets in my experience Yes I know you put in a new coil but you need to know you have a working tester before throwing more parts at it

Thanks. Tested spark tester on a friend's saw and it seemed to work on the SE setting. I guess coil could be defective, I hardwired a ground right to the kill switch and get great spark on a plug but not even a pop when trying to actually start the saw.

 

[dboyd351]

So if it looks like you are getting fire now, it is time to put a squirt of mix in the carb and see if it will light off

 

[jff]

So if it looks like you are getting fire now, it is time to put a squirt of mix in the carb and see if it will light off

Well, I was getting spark before, what wasn't clear was whether it was firing inside the chamber. Tried again with some premix in the chamber and got nothing, not even a pop

 

[muddy42]

Sorry I am a bit confused now. Is the following a correct description of the current situation.
- You have replaced the coil with a new OEM one and tried multiple new spark plugs.
- you can get a spark by simply grounding the spark plug on the cylinder and pulling the cord, but the engine still doesn't pop.
- When using the spark tester on your saw you don't get a spark, but when using the spark tester in exactly the same way on another known working saw you do get a spark?

If that is true, I'd suspect you still have a problem with the coil or magnets. Try fitting with the narrowest business card possible or a piece of paper. or send the coil back with a video of the test results and get another one.

The following ideas are fairly long shots:
- A seriously blocked muffler or spark arrester can hinder ignition.
- Have you checked for air leaks? My understanding is you can still have compression with an air leak. A serious air leak (like a disconnected impulse etc.) will stop the transfer ports working.
- as above worn piston skirts

 

[jff]

Sorry I am a bit confused now. Is the following a correct description of the current situation.
- You have replaced the coil with a new OEM one and tried multiple new spark plugs.
- you can get a spark by simply grounding the spark plug on the cylinder and pulling the cord, but the engine still doesn't pop.
- When using the spark tester on your saw you don't get a spark, but when using the spark tester in exactly the same way on another known working saw you do get a spark?

If that is true, I'd suspect you still have a problem with the coil or magnets. Try fitting with the narrowest business card possible or a piece of paper. or send the coil back with a video of the test results and get another one.

The following ideas are fairly long shots:
- A seriously blocked muffler or spark arrester can hinder ignition.
- Have you checked for air leaks? My understanding is you can still have compression with an air leak. A serious air leak (like a disconnected impulse etc.) will stop the transfer ports working.
- as above worn piston skirts

-Not sure if coil was OEM, but it was highly rated. However, it was for a Husqvarna 50, which may be different from a Husqvarna racher 50? (see above question about flywheels)

-I can get spark by grounding the plug on the head and pulling, but no pop in the engine.

-Yes, no spark on the rancher, but I got a spark on my friend's saw

Re: long shots:
- muffler looks clear
- I haven't done a leakdown or anything, but I have good compression, more than I would expect with a leak. If I'm able to get 150+ PSI after a few pulls, I guess there may be a leak, but doesn't that imply that the compression is "good enough" to expect a pop, at least?
- piston looks pretty good. Some scratches, but no deep scores or anything.

Thanks!

 

[Chevboy0167]

Long shot........ Get a multimeter or volts/ohm meter and test resistance/ohms from cylinder to coil ground where the bolt goes through. Note this reading/write it down. Then test from cylinder to crankcase bare aluminum spot somewhere. Note the reading.

These 2 readings should be exactly the same or pretty damn close. Let us know what the readings are.

There should be low or no resistance between the 2 "ground paths" to complete the ground circuit to the spark plug hex case. The same goes for the coil ground path to crankcase.

 

[muddy42]

-Not sure if coil was OEM, but it was highly rated. However, it was for a Husqvarna 50, which may be different from a Husqvarna racher 50? (see above question about flywheels)

-I can get spark by grounding the plug on the head and pulling, but no pop in the engine.

-Yes, no spark on the rancher, but I got a spark on my friend's saw

Re: long shots:
- muffler looks clear
- I haven't done a leakdown or anything, but I have good compression, more than I would expect with a leak. If I'm able to get 150+ PSI after a few pulls, I guess there may be a leak, but doesn't that imply that the compression is "good enough" to expect a pop, at least?
- piston looks pretty good. Some scratches, but no deep scores or anything.

Thanks!

I've had odd experiences with chinese replacement coils. I'd send the coil back and try an OEM one or if one is not available try to get an original one from a broken rancher.

Plus I'd really pressure/vac test the saw as the foundation of any tricky saw diagnosis. I know the saw should technically pop even with a bad leak, but I'd want to know before spending more time and money.

 

[Big_Eddy]

If changing the coil made no difference, I’d put the original back on. Why introduce additional variables