Husqvarna 435 Hard To Start

[2lumbarleft]

I'd like to resurrect this thread because i was given a 435 in place of payment for a job I did for a guy. He owed me a deuce and said his little used saw was worth $300.
I can see why he gave it to me.
I got it running well. Did a carb rebuild. Followed starting directions and when cold, it pops right up.
This saw WILL NOT restart no matter what I do.
Husqvarna is of little to no help. The guy said he bought this saw around 5 or 6 years ago and indeed, it is little used.
Is there some secret as to why this saw doesn't want to re-start and more importantly, the fix?

Can I assume that you have a carb adjustment tool or modified the jet screws to use a flat blade screw driver? If you rebuilt your carb, you probably are savvy enough to know how to re-tune the carburetor, but I needed to ask. My first thought is the saw is still running lean, gets hot, boils the gas out of the carburetor after it rests a bit, not running. Also, if the saw starts when the fuel tank is full, vs not starting after half the tank is gone, you might want to check for a cracked fuel line. I can't tell you how many of these saws I have looked at, where the saw is not running and the fuel line looks like 1" sections of broken spaghetti noodles laying in the bottom of the tank Thanks ethanol! Regardless of whether you can fix the saw, if you are senior gentlemen with shoulder problems, you might want to consider an Echo CS-400, muffler modded and retuned. Easy to start, and cuts close to a 50cc saw in speed. Cheap air filters and chains available everywhere.

 

[arro222]

Here's the thing 2, first thanks for the response. I was a professional logger at one point in my life and still cutting.
If I have not had 50 chainsaws, I haven't had one.
The lines in the saw seem fine. I pressurized them and no leaks as simply blowing through them tells one nothing.. The saw is like brand new so it makes me believe this starting issue was from the get-go and is why the previous owner didn't use it much.
Why'd they put what looks like plastic jet needles in the thing?
Not bragging, just giving you a better idea of self which certainly lends itself to any chainsaw equation.
This 435 has become like an obsession to me. I have tried everything I know about chainsaws including , vents, ignition, carbs, hard starting, no starting, fuel adjustments, fuel lines, muffler clogs, spark etc, etc, etc.
I have never owned a chainsaw like this one however. I am used to one pull starts when a saw is warmed up.
This one gets worse when warmed.
This 435 saw seems to be all over the internet as far as its starting issues and I pride myself with getting any chainsaw running right.
This one has become like my "white whale" however and now wondering if it is something with the Zama carb.
Makes me wonder if I just shouldn't have gotten an entire carb for it.
Whatever it is, Husqvarna has been pretty shut up about any issue this saw has in this regard.
This saw has to have given Husq a bad name.

 

[2lumbarleft]

Here's the thing 2, first thanks for the response. I was a professional logger at one point in my life and still cutting.
If I have not had 50 chainsaws, I haven't had one.
The lines in the saw seem fine. I pressurized them and no leaks as simply blowing through them tells one nothing.. The saw is like brand new so it makes me believe this starting issue was from the get-go and is why the previous owner didn't use it much.
Why'd they put what looks like plastic jet needles in the thing?
Not bragging, just giving you a better idea of self which certainly lends itself to any chainsaw equation.
This 435 has become like an obsession to me. I have tried everything I know about chainsaws including , vents, ignition, carbs, hard starting, no starting, fuel adjustments, fuel lines, muffler clogs, spark etc, etc, etc.
I have never owned a chainsaw like this one however. I am used to one pull starts when a saw is warmed up.
This one gets worse when warmed.
This 435 saw seems to be all over the internet as far as its starting issues and I pride myself with getting any chainsaw running right.
This one has become like my "white whale" however and now wondering if it is something with the Zama carb.
Makes me wonder if I just shouldn't have gotten an entire carb for it.
Whatever it is, Husqvarna has been pretty shut up about any issue this saw has in this regard.
This saw has to have given Husq a bad name.

Here is what I would suggest. Please remove the spark plug, drop the piston to the bottom of the cylinder and shine a light in through the spark plug hole. This will only allow you to view the exhaust side of the cylinder. Could you please tell me if you see any vertical dark lines? If you would like to go a step further, remove the muffler and you will be able to see the intake side of the cylinder, as well as exterior wall of the piston when you move it back up from bottom dead center. If you see marks on the piston, or cylinder walls, you may likely have a scored piston or cylinder. As long as you still have 115 psi of compression the saw will start. But as the saw runs, if the cylinder walls or piston are scored, the saw will seize and shut down. If this is indeed the case, then the likely cause was running the saw too lean (not your fault). The factory set the saws lean to pass the emission test standards. The problem back around 2012 was so pervasive that returned saws caused Amazon to stop allowing ads temporarily from selling these saws. They were great saws. Just miss-tuned right from the factory.

 

[arro222]

I checked for that 2. Walls are fine. If I don't shut off the saw, she'll just keep running.
What I did discover was the previous owner mustn't have put the clutch cover back on correctly as the drum spring looked scorched and it really doesn't hold the saw in abeyance when engaged.
If he just kept running the saw in this fashion, I wonder if the sheer heat of this constant friction screwed up the saw in some way.

There is also a point where I can't seem to work out a "pulsing" of the saw at high speed with any type of carb adjustment rich or lean.
I believe I made a bad transaction and should have insisted the guy give me my due cash.

 

[2lumbarleft]

I checked for that 2. Walls are fine. If I don't shut off the saw, she'll just keep running.
What I did discover was the previous owner mustn't have put the clutch cover back on correctly as the drum spring looked scorched and it really doesn't hold the saw in abeyance when engaged.
If he just kept running the saw in this fashion, I wonder if the sheer heat of this constant friction screwed up the saw in some way.

There is also a point where I can't seem to work out a "pulsing" of the saw at high speed with any type of carb adjustment rich or lean.
I believe I made a bad transaction and should have insisted the guy give me my due cash.

Unfortunately, there are limits to what can be accomplished through on line advice, but the rpm variation at high speed sounds like one of two things. One is that there could be a vacuum leak. With such a new saw, I wouldn't think the problem to be crank seals, but have you noticed if the pulsing is worse when you tip the saw to either side while under high speed throttle? After a cut and releasing the throttle trigger, does the saw seem to linger at high rpm before settling down to a high idle, and then after idling a few seconds, slow even more? The other cause might be inconsistent or improper fuel flow. You may have already disregarded a potential cause due to a defective component in the system or confidence in your tuning technique. You may have to start from scratch. Fuel filter, fuel lines, purge bulb, carburetor, impulse line. At some point, you will have to make a decision as to how much time and effort you wish to place into this puzzle. As far as the burned clutch housing, I wonder if the original owner wasn't operating the saw without refilling the bar oil reservoir. I have seen that before. Out of curiosity how many turns out are you on the low and high speed settings right now? I wish I knew where your maximum no load rpm peak is right now.

 

[arro222]

Let me recall 2. I think I'm 2-2.5 turns on the low and close to two on the high. I've done everything from 8 turns to 1 turn and a myriad of combinations thereafter.
I notice what I would not call a great "seal" of the carb to engine from Husq. Seems like there should be something else there. When I took the carb apart, it was missing an internal gasket but the diaphragm gasket was thicker on the original than what came with the Zama kit..
I will try the sideways technique and see what happens.
I believe I did notice your second observation of slowness in down throttle response last night.
It limbs pretty good but loses power in extended cut.
I have about reached my limit but will give it another go.

As a logger, we really didn't mess too much with our saws running wise. After 2 yrs they were just about worn out.
Time was money and 3 other guys weren't gonna wait for you to figure out why your saw was running crazily.
We just bought new ones but that started a terrible fetish after I retired.
I bought saws just to try out and sold them for 3/4's of what I paid for the things.
I had to go cold turkey (the wife helped with that) as there wasn't any chainsaw addiction centers.

 

[2lumbarleft]

Let me recall 2. I think I'm 2-2.5 turns on the low and close to two on the high. I've done everything from 8 turns to 1 turn and a myriad of combinations thereafter.
I notice what I would not call a great "seal" of the carb to engine from Husq. Seems like there should be something else there. When I took the carb apart, it was missing an internal gasket but the diaphragm gasket was thicker on the original than what came with the Zama kit..
I will try the sideways technique and see what happens.
I believe I did notice your second observation of slowness in down throttle response last night.
It limbs pretty good but loses power in extended cut.
I have about reached my limit but will give it another go.

As a logger, we really didn't mess too much with our saws running wise. After 2 yrs they were just about worn out.
Time was money and 3 other guys weren't gonna wait for you to figure out why your saw was running crazily.
We just bought new ones but that started a terrible fetish after I retired.
I bought saws just to try out and sold them for 3/4's of what I paid for the things.
I had to go cold turkey (the wife helped with that) as there wasn't any chainsaw addiction centers.

Regarding tuning, I realize that you are using a replacement carburetor, but it should tune pretty much the same. The low speed jet is your transition jet. It helps you get from idle, up into your working range. As you enrich the low speed jet, the lower your engine idle will go, so you may need to temporarily advance your throttle screw to keep things running. Naturally, when a saw is cold, it doesn't want to advance as quickly as it does when hot. When you enrich the low speed jet a little, you will notice that the saw responds faster when cold. But you will have problems if your low speed jet is too rich. When your saw comes down off high speed returning to idle, it will load up and die if your low speed jet is to rich. For the time being, you should be good with an initial low speed setting of 2 1/2 turns. The high speed jet, that is the one farthest from the engine, you will likely need at least 1 1/2 turns for the H435 model. Every saw is just a little different, based on running time and how clean the carburetor is, etc. Some need about 2 1/2 - 3 turns out. I like to set them rich to where you can hear the saw burble as it hits the limit of high speed operation. This is called four cycling. From this point, you lean up. If you lean up too much, that sound will disappear. You want to burble outside the cut and have the sound clean up inside the cut. Some of this is personal judgement, watching how the saw cuts, but having a tachometer is very useful. I don't need one anymore, but I still use them to insure the saw is not overrevving. They also speed things up with diagnostics. Lets say your saw is at full operational temperature and you take your first high speed no load reading, and it comes in at 10,600. You know right away you are too rich. For your model, I like to set them around 12,100 to 12,200 rpm. Never run your saw for more than 5 or 6 seconds like this. It takes a little extra fuel to have real pulling power in the channel, but you will also lose power if you enrich beyond your saws sweet spot. What concerns me most, is your last comment on the saw losing power in the cut. When a saw revs good, hits the wood and starts cutting great, then loses steam after several seconds with nothing else changing, then you are likely looking at a vacuum leak. Many people try to richen up the high speed jet to compensate for the air leak, but you are just heading for engine failure, and accelerating the process by continuing to use the saw. Good luck! I'm outta here.

 

[arro222]

Regarding tuning, I realize that you are using a replacement carburetor, but it should tune pretty much the same. The low speed jet is your transition jet. It helps you get from idle, up into your working range. As you enrich the low speed jet, the lower your engine idle will go, so you may need to temporarily advance your throttle screw to keep things running. Naturally, when a saw is cold, it doesn't want to advance as quickly as it does when hot. When you enrich the low speed jet a little, you will notice that the saw responds faster when cold. But you will have problems if your low speed jet is too rich. When your saw comes down off high speed returning to idle, it will load up and die if your low speed jet is to rich. For the time being, you should be good with an initial low speed setting of 2 1/2 turns. The high speed jet, that is the one farthest from the engine, you will likely need at least 1 1/2 turns for the H435 model. Every saw is just a little different, based on running time and how clean the carburetor is, etc. Some need about 2 1/2 - 3 turns out. I like to set them rich to where you can hear the saw burble as it hits the limit of high speed operation. This is called four cycling. From this point, you lean up. If you lean up too much, that sound will disappear. You want to burble outside the cut and have the sound clean up inside the cut. Some of this is personal judgement, watching how the saw cuts, but having a tachometer is very useful. I don't need one anymore, but I still use them to insure the saw is not overrevving. They also speed things up with diagnostics. Lets say your saw is at full operational temperature and you take your first high speed no load reading, and it comes in at 10,600. You know right away you are too rich. For your model, I like to set them around 12,100 to 12,200 rpm. Never run your saw for more than 5 or 6 seconds like this. It takes a little extra fuel to have real pulling power in the channel, but you will also lose power if you enrich beyond your saws sweet spot. What concerns me most, is your last comment on the saw losing power in the cut. When a saw revs good, hits the wood and starts cutting great, then loses steam after several seconds with nothing else changing, then you are likely looking at a vacuum leak. Many people try to richen up the high speed jet to compensate for the air leak, but you are just heading for engine failure, and accelerating the process by continuing to use the saw. Good luck! I'm outta here.

Don't blame ya.
Carb is original however.
One other thing, if this saw acts the way you describe when turned sideways with the pulsing worsening, what is that an indicator of again?
Thanks for your help.