Husqvarna 257 won't start....

[PushnFords]

First of all, I don't know the history on this saw but it doesn't look like it has been abused. When I got it I checked for spark & with an adjustable spark checker it jumped a 3/16" gap. Compression test showed 120lbs. Disassembled the carb, cleaned, & put a kit in it...which I've done many times with good results. Put the old Champion plug back in because it was pretty clean...since then I've tried a new Champion & a new NGK. The very first time I pulled it I got a little hiccup but nothing at all since. If I pull on it for a while the plug will get wet but not fire off or even try to start. I've tried the adjusting screws in various positions from 1/2 turn out to 1 1/2 turns and no change. I have spark...I have compression...I have fuel...but I do not have a running saw! :msp_mad: I've never seen it happen on a saw but I did pull the flywheel off to make sure the "key" cast in was ok & it was.

Any thoughts or ideas on what I should check next?

 

[super3]

First of all, I don't know the history on this saw but it doesn't look like it has been abused. When I got it I checked for spark & with an adjustable spark checker it jumped a 3/16" gap. Compression test showed 120lbs. Disassembled the carb, cleaned, & put a kit in it...which I've done many times with good results. Put the old Champion plug back in because it was pretty clean...since then I've tried a new Champion & a new NGK. The very first time I pulled it I got a little hiccup but nothing at all since. If I pull on it for a while the plug will get wet but not fire off or even try to start. I've tried the adjusting screws in various positions from 1/2 turn out to 1 1/2 turns and no change. I have spark...I have compression...I have fuel...but I do not have a running saw! :msp_mad: I've never seen it happen on a saw but I did pull the flywheel off to make sure the "key" cast in was ok & it was.

Any thoughts or ideas on what I should check next?

A good hot spark, or just spark?

 

[zogger]

Pull the on/off switch wire off and make sure the metal end isn't grounded, maybe with some tape, then check for spark again.

 

[AKDriveSprocket]

Pull the plug out and turn it up side down and pull on the rope to get the rest of the gas out of the crank case and start over.

 

[PushnFords]

A good hot spark, or just spark?

My spark tester is just a light. I thought it looked a little dim so I took it to a friend that has an adjustable one. I really didn't expect it to jump the big gap that it did. It was a really thin spark...so maybe it is a weak coil?

Pull the on/off switch wire off and make sure the metal end isn't grounded, maybe with some tape, then check for spark again.

Wire looks good. If it was shorting out I'd expect no spark vs. what may or may not be a weak spark. But easy enough to experiment with once I put it back together.

 

[super3]

My spark tester is just a light. I thought it looked a little dim so I took it to a friend that has an adjustable one. I really didn't expect it to jump the big gap that it did. It was a really thin spark...so maybe it is a weak coil?


If you used an adjustable gap tester like the one I have it should jump a 3/8" gap with a good strong wide spark. I repaired a 254 with the same symptoms as you described. Spark was thin and only jump a 1/8- 3/16" gap.

Weak coil is my guess.

 

[ncfarmboy]

Never use a spark checker with a light them dang things will light up with any current. I used one on a 009 I was working on couldn't get it to run. Finally after much frustration checked it with a gap style no spark. New coil Bam good to go. Threw that New light checker away. Got it in a "Lot" of tools I bought.
Shep

 

[PushnFords]

I'd originally bought a Lisle adjustable spark tester but that thing was crap...it would fly apart if you looked at it wrong. I'm going to catch the MAC truck tomorrow and see if he has anything decent. The adjustable tester my friend has is nice but it is probably 20+ years old.

These saws are enough to drive me crazy. A friend was watching me rebuild the carb on my father in law's Stihl...quick & easy...fired right up...adjusted nice...ran great. So he brought his in. I bit the bullet & ordered a coil for the 257 today...will be here tomorrow for $64 after shipping. Also been working on his MS250 that was his grandpa's saw. Carb gaskets were nasty so rebuilt it & put new mix in. Found a crack in the inlet fuel hose right after that so got that fixed. Finally got it started but won't hold a constant speed & races...I found a home built pressure/vacuum tester on here that I'm copying...parts aren't here yet though.

Yesterday & today I've been working on his 010 AV. The plastic fuel inlet elbow was broken so I rebuilt the carb & replaced the elbow with a metal one. I got it running but trying to adjust "L" it never does sound that good...doesn't run that fast...runs best with 1.5 turns out...and when I try to lean it out it'll slow down just a touch & then die like I hit the kill switch. Fire it back up...tried to adjust "H". Richen it up until it 4 strokes & back off just a touch...suddenly dies & won't restart. Not sure what the problem with it is but I may end up checking the crankcase pressure/vacuum on it too unless someone has a better idea. :msp_angry:

 

[jockeydeuce]

As far as the 257 goes....That's really low compression @ 120....I would pull the muffler and have a look at the piston before you go much further.

 

[PushnFords]

As far as the 257 goes....That's really low compression @ 120....I would pull the muffler and have a look at the piston before you go much further.

It could actually be higher. Not long after I tested the 257 I was testing some trimmers and got readings around 60. Eventually suspected something wasn't right & found the schrader valve in the end was bad. I don't have the recoil on at the moment to test again.

 

[272super]

It could be the coil,but it also shows all the signs of being flooded. Pull plug,invert saw and see how much fuel drains out of case. If fuel does come out,drain it,dry plug and try to start.Open throttle wide open until it starts. Been down that road many times and a bad needle is all it takes to flood after it sits unused.

 

[PushnFords]

Put the new coil on yesterday & wouldn't start. Pulled the carb today & replaced the inlet needle & still wouldn't start. Removed the carb, sprayed it out with carb cleaner...wouldn't start. Removed the carb, sprayed it out with carb cleaner, air, then carb cleaner again trying to see if maybe the welch plug was leaking (wasn't that I could tell) and it started. I've got it mostly adjusted now. I went to cut into a piece of hedge to see how it ran & the chain is really dull. I'll send it out to be sharpened & do the final adjustment this weekend...hopefully nothing changes. So apparently there was something in the carb causing the problem...somewhere...

 

[LarryRFL]

Advise to learn to use a file and sharpen your own chains in 3 ... 2 ... 1

 

[295 tramp]

check the metering lever if it is an hda carb the tab that the diaphragm hits should be level with the base of the carb.
also if the head has a compression release make sure that it is out when trying to start

 

[PushnFords]

Well I have a sharpened chain on the saw. From cold it will pop after 4-6 pulls with the choke on & compression release pushed in. Push in the choke and it'll start after a couple more pulls. Idles good, revs good, cuts pretty good, etc. I adjusted the high side by backing it out until it started to drop RPM a little (doesn't really sound like it 4 strokes...at least I can't hear it clear). But I also found that it will run & run pretty fast with the H screw all the way in. Is that a possible crankcase leak or the carb leaking air?
.
And yes the needle lever is set level with the body of the carb.