Husqvarna 435 Bogs and Dies

[skirby]

Hello Everyone,

I have a strange issue with a 435. It will start and run fine, after some time idling it will bog and die as soon as you hit the throttle. It will fire right back up after and run again, revs fine, then again, after some time idling it will bog and die when you go to rev it. Carb is tweaked just a bit from factory settings, idle is good, very crisp throttle response and high is set correctly. The coil air gap is 0.01”, air filter is clear, fresh fuel and new fuel filter. Could it be the coil starting to go?

 

[epo]

Hello Everyone,

I have a strange issue with a 435. It will start and run fine, after some time idling it will bog and die as soon as you hit the throttle. It will fire right back up after and run again, revs fine, then again, after some time idling it will bog and die when you go to rev it. Carb is tweaked just a bit from factory settings, idle is good, very crisp throttle response and high is set correctly. The coil air gap is 0.01”, air filter is clear, fresh fuel and new fuel filter. Could it be the coil starting to go?

It seems that your suspicion is justified.

 

[singinwoodwackr]

Hello Everyone,

I have a strange issue with a 435. It will start and run fine, after some time idling it will bog and die as soon as you hit the throttle. It will fire right back up after and run again, revs fine, then again, after some time idling it will bog and die when you go to rev it. Carb is tweaked just a bit from factory settings, idle is good, very crisp throttle response and high is set correctly. The coil air gap is 0.01”, air filter is clear, fresh fuel and new fuel filter. Could it be the coil starting to go?

.01?
I set my coils at .020
Possibly the the thing heats up a tad and makes that .010 even tighter?

 

[epo]

.01?
I set my coils at .020
Possibly the the thing heats up a tad and makes that .010 even tighter?

If this is how the gap is set, it is fully consistent with the manufacturer's data. Stihl even allows 0.15 mm for small saws.

As close as possible, without touching.

 

[skirby]

.01?
I set my coils at .020
Possibly the the thing heats up a tad and makes that .010 even tighter?

It was a much larger gap first before I set it to that. I believe that’s what factory calls for is 0.01, but I could be wrong. Same issue in either position though.

 

[epo]

It was a much larger gap first before I set it to that. I believe that’s what factory calls for is 0.01, but I could be wrong. Same issue in either position though.

The default value is 0.3 mm with a tolerance of 0.1 mm. That is, if you really set 0.01'', or 0.254 mm, it is OK. See the first image I pasted above.

 

[skirby]

The default value is 0.3 mm with a tolerance of 0.1 mm. That is, if you really set 0.01'', or 0.254 mm, it is OK. See the first image I pasted above.

So what could be causing it to run for a bit, then after idling for a while, touching the trigger will cause it to bog and die? It’s able to rev no problem until it idles for a bit, then when you hit the trigger it bogs.

 

[ballisticdoughnut]

How old is the saw? How long has it sat since last use? Are you running E10 or non ethanol fuel
In it? Sounds like you may need to rebuild the carb or may be a simple adjustment.

 

[epo]

So what could be causing it to run for a bit, then after idling for a while, touching the trigger will cause it to bog and die? It’s able to rev no problem until it idles for a bit, then when you hit the trigger it bogs.

Are you able to check right after it dies in what condition the spark plug is? Is it dry or wet from fuel at that time? You can post a picture here if possible....

 

[skirby]

How old is the saw? How long has it sat since last use? Are you running E10 or non ethanol fuel
In it? Sounds like you may need to rebuild the carb or may be a simple adjustment.

It’s an ethanol blended 91 octane fuel. The saw has sat for a few years but was put away for this exact issue that’s happening. It was used as a firewood saw. It’s a 2013. The saw will rev fine and the low is adjusted nicely so the throttle response is very crisp, the high is also adjusted correctly, I don’t believe it’s an adjustment issue. If it was a carb issue, would it not just bog every time? It’ll cut fine, but after having it wide open cutting, then letting it idle, as soon as you grab it again that’s when it bogs and dies. Will fire right up immediately after.

 

[skirby]

Are you able to check right after it dies in what condition the spark plug is? Is it dry or wet from fuel at that time? You can post a picture here if possible....

It’s golden brown and dry. Almost seems like the spark is a bit weak because when testing the spark it looked orange to yellowish. Swapped plugs to a new one and tested and same colour spark. That’s why I’m wondering if the coil is causing this whole issue.

 

[ballisticdoughnut]

It’s an ethanol blended 91 octane fuel. The saw has sat for a few years but was put away for this exact issue that’s happening. It was used as a firewood saw. It’s a 2013. The saw will rev fine and the low is adjusted nicely so the throttle response is very crisp, the high is also adjusted correctly, I don’t believe it’s an adjustment issue. If it was a carb issue, would it not just bog every time? It’ll cut fine, but after having it wide open cutting, then letting it idle, as soon as you grab it again that’s when it bogs and dies. Will fire right up immediately after.

First thing I’d do is vacuum/pressure test the saw. If it passes rebuild the carb. The symptom you describe doesn’t indicate a coil problem to me. Could be a tank vent issue, however considering the saw is 11 years old I’d say a carb rebuild should take priority here.

 

[epo]

It’s golden brown and dry. Almost seems like the spark is a bit weak because when testing the spark it looked orange to yellowish. Swapped plugs to a new one and tested and same colour spark. That’s why I’m wondering if the coil is causing this whole issue.

The fact that the plug is dry may suggest that it is not an ignition problem. Although it's worth checking the coil anyway, because later you can spend a lot of time looking somewhere else without results.
Of simple things, you can check the tank venting by slightly loosening the fuel cap (saw lying on its side) before revving up again.

 

[cookies]

Had the same issue with my 435, carb rebuild, spark plug and fuel filter and she ran great again. After the rebuild the carb needed adjustment because the carb is now pumping fuel properly.

 

[skirby]

Had the same issue with my 435, carb rebuild, spark plug and fuel filter and she ran great again. After the rebuild the carb needed adjustment because the carb is now pumping fuel properly.

Perfect. Thanks for the reply, I was searching for someone else who experienced this issue with no luck.

 

[skirby]

Update: the plastic choke lever that the return spring rests on was broke so the choke would never fully go back to the run position. Also, the Husky dealer said that the old school carb kit is no more, all you get now are seals and a diaphragm, the seals and diaphragm are around $25 CAD, while a whole new carb is $53 CAD. I just purchased the new carb and the saw is running perfect.

Thanks everyone for your help! Much appreciated!