395xp Hard Start, Tuning Issues - Bad Coil?

[gvsu141]

I have a 2014 year 395xp that has been giving me fits. Issue started a few months back. Only thing left I can think to check is the coil. Would like confirmation before I drop some more $ on this. Note, I have the black coil. (Not the blue limited one) My issue is 2 fold:

1. Rev/Max RPM issue. Acts like it is running very rich, and have a hard time to get it to rev out. If I play with adjustments, I can now get it to 12,500 RPM after it warms up, but still acts like the most extreme rich/4 stroking I have seen. H screw needs to be set only 3/4 turns out. Anything more and it will bog and not rev at all. Even if turned all the way in, it still acts like it wants to 4 stroke and max at 12,500 RPM. L screw works best 1.25-1.5 turns out.
2. Hard/no start warm. When warm at all, very hard to start. Can often pull 20-30 times with no pop, regardless of choke setting. Plug looks normal - wet, but not flooded. This issue happens even after 1-2 quick test cuts. Latest test, it died when idling warm. I could not see any spark, though it was very bright out. By the time I got back to the garage I had spark and started after 2-3 pulls.

Recent tests:
-Compression: 161 cold, 155 hot. No scoring on piston/cylinder.
-New Spark Plug - Tried Champion and NGK
-Gas tank Vent working. Fuel/pulse lines in good shape
-New OEM Walbro carb kit. Metering checked/set with OEM tool
-Always run non-ethanol rec fuel
-Pressure/vac test with Mityvac on pulse line. No leaks found.
-Coil gap set with business card
-Flywheel key in good shape.
-Exhaust screen clear. Tried OEM and aftermarket Dukes exhaust
-Unplugged kill switch - no change
-Carb adjusted all over - limiters removed

Am I correct in trying a new Coil next? I am not the original owner, so the Husqvarna lifetime coil warranty likely will not be an option.

 

[Ozhoo]

Pressure test the carb before anything else. Apply 8-10psi to the fuel inlet of the carb, it sould hold that pressure indefinitely.

 

[gvsu141]

Pressure test the carb before anything else. Apply 8-10psi to the fuel inlet of the carb, it sould hold that pressure indefinitely.

Thanks, I missed checking this before. I just pumped it up to 10 psi and came back after a few minutes and was still holding exactly 10psi.

 

[J D]

I'd say you're at the point of replacing the coil... quite a few of the Husky coils will interchange so you may be able to "borrow" one of another saw to prove it either way

 

[gvsu141]

I'd say you're at the point of replacing the coil... quite a few of the Husky coils will interchange so you may be able to "borrow" one of another saw to prove it either way

Didn't realize they swapped. I was able to take the one off one of my 262's and it bolted right up. Quick bench test in the garage was promising. Going to test it this weekend in the woods.

 

[gvsu141]

Quick update saw is fixed and running great again.

Swapped the known good coil from the 262xp, no difference. Still not running right.

At this point, I was about stumped, so decided to swap the NGK plug from the 262 as well. Sure enough, the saw fired right up in 1/2 pull!

Turns out both of the brand new Champion plugs I tried were junk out of the box. Would spark ok cold but not hot.

Have the original 395 coil back in and tuned slightly rich at just over 12,000 rpm for milling, about 7/8 turns out on H. It rips again!

Thanks for the coil swap tip, saved me the $90+ for a new coil.

 

[grizz55chev]

Quick update saw is fixed and running great again.

Swapped the known good coil from the 262xp, no difference. Still not running right.

At this point, I was about stumped, so decided to swap the NGK plug from the 262 as well. Sure enough, the saw fired right up in 1/2 pull!

Turns out both of the brand new Champion plugs I tried were junk out of the box. Would spark ok cold but not hot.

Have the original 395 coil back in and tuned slightly rich at just over 12,000 rpm for milling, about 7/8 turns out on H. It rips again!

Thanks for the coil swap tip, saved me the $90+ for a new coil.

Moral of the story, the simple things first. It's kinda rare that plugs fail, but it will drive you crazy when they do!

 

[gvsu141]

Moral of the story, the simple things first. It's kinda rare that plugs fail, but it will drive you crazy when they do!

Yep. The crazy thing is that was the first thing I tried. Would never have thought that two brand new plugs would both be junk. I guess I remember why I usually run NGK.

As a positive, I have inspected every square inch of this saw, should be like brand new now.

 

[lone wolf]

Moral of the story, the simple things first. It's kinda rare that plugs fail, but it will drive you crazy when they do!

Most people assume new parts should work ,this can drive anyone crazy and lead to a long list of expenses ,other parts and time wasted. Ask me how I know.

 

[lone wolf]

Yep. The crazy thing is that was the first thing I tried. Would never have thought that two brand new plugs would both be junk. I guess I remember why I usually run NGK.

As a positive, I have inspected every square inch of this saw, should be like brand new now.

Are they in fact junk did you cross check them in another saw?

 

[gvsu141]

Are they in fact junk did you cross check them in another saw?

I have not, I would be curious to see. I would be surprised if it would change anything, since it had low/no visual spark when warm with both the 395 and 262 coil.

 

[lone wolf]

I have not, I would be curious to see. I would be surprised if it would change anything, since it had low/no visual spark when warm with both the 395 and 262 coil.

I would be more surprised if the did not work. Let us know please.

 

[gvsu141]

I would be more surprised if the did not work. Let us know please.

Will do. Probably won't get to it for a day or two.

 

[JayPopple]

I have a 2014 year 395xp that has been giving me fits. Issue started a few months back. Only thing left I can think to check is the coil. Would like confirmation before I drop some more $ on this. Note, I have the black coil. (Not the blue limited one) My issue is 2 fold:

1. Rev/Max RPM issue. Acts like it is running very rich, and have a hard time to get it to rev out. If I play with adjustments, I can now get it to 12,500 RPM after it warms up, but still acts like the most extreme rich/4 stroking I have seen. H screw needs to be set only 3/4 turns out. Anything more and it will bog and not rev at all. Even if turned all the way in, it still acts like it wants to 4 stroke and max at 12,500 RPM. L screw works best 1.25-1.5 turns out.
2. Hard/no start warm. When warm at all, very hard to start. Can often pull 20-30 times with no pop, regardless of choke setting. Plug looks normal - wet, but not flooded. This issue happens even after 1-2 quick test cuts. Latest test, it died when idling warm. I could not see any spark, though it was very bright out. By the time I got back to the garage I had spark and started after 2-3 pulls.

Recent tests:
-Compression: 161 cold, 155 hot. No scoring on piston/cylinder.
-New Spark Plug - Tried Champion and NGK
-Gas tank Vent working. Fuel/pulse lines in good shape
-New OEM Walbro carb kit. Metering checked/set with OEM tool
-Always run non-ethanol rec fuel
-Pressure/vac test with Mityvac on pulse line. No leaks found.
-Coil gap set with business card
-Flywheel key in good shape.
-Exhaust screen clear. Tried OEM and aftermarket Dukes exhaust
-Unplugged kill switch - no change
-Carb adjusted all over - limiters removed

Am I correct in trying a new Coil next? I am not the original owner, so the Husqvarna lifetime coil warranty likely will not be an option.

I would recommend you find out what the air gap between the magnets and the coil is supposed to be by the manual and set it with brass feeler gauges. Weak spark can be a reason for your issues. An other thing just for the heck of replace the flyway key with a new one. They do distort but to tell you the truth I have never experienced that. It usually takes some sort of a hard strike to the drive train to sheer a key.

 

[husqvfixit]

I would recommend you find out what the air gap between the magnets and the coil is supposed to be by the manual and set it with brass feeler gauges. Weak spark can be a reason for your issues. An other thing just for the heck of replace the flyway key with a new one. They do distort but to tell you the truth I have never experienced that. It usually takes some sort of a hard strike to the drive train to sheer a key.

Absolutely agree. Worth properly adjusting the air gap: often (not sure on bigger saws, only worked on medium and small saws) the gap is hair thin.

 

[JayPopple]

Absolutely agree. Worth properly adjusting the air gap: often (not sure on bigger saws, only worked on medium and small saws) the gap is hair thin.

I also advise checking the coil with a multimeter. A manual or the Internet would have the specifications and testing procedure.

 

[gvsu141]

All good advice. My issue in this case was the 2 different Champion plugs that were bad out of the box. Been running fine ever since with the NGK.

 

[JayPopple]

All good advice. My issue in this case was the 2 different Champion plugs that were bad out of the box. Been running fine ever since with the NGK.

Unusual to have bad plugs new from the manufacture but a long as you are up and running.

 

[Campin' Cutter]

Just a thought, but did you gap the new plugs? Not sure if it's possible for a plug to spark cold and not hot, but wouldn't surprise me. Didn't see you mention you gapped the new plugs so the thought crossed my mind. I would think it really unlikely that two brand new plugs were bad out of the box, but I suppose it could happen.

 

[husqvfixit]

Just a thought, but did you gap the new plugs? Not sure if it's possible for a plug to spark cold and not hot, but wouldn't surprise me. Didn't see you mention you gapped the new plugs so the thought crossed my mind. I would think it really unlikely that two brand new plugs were bad out of the box, but I suppose it could happen.

Good point. Especially with known good companies.