Husqvarna 545 dies when tilted either side or forward, but ONLY when hot

[1d10t]

For the carb cleaner, thats a no go, I already had air leak problems and replaced head gasket since then, doesn't seem to be anymore leaks.

From what is happening (saw will just cut out instantly, as if it was turned off rather than flooded/leaned out and will also instantly start back if starter rope is pulled - no difficulty at all) it actually does seem like an electrical issue. This has actually been happening for some years or so I'm told (not my saw) but only when saw is hot.

Also, how sensitive should the kill switch be? It's one of those push down to kill, up and out for choke, up and out and then back to normal position for high idle switches.

Right now the switch needs only be touched and thee saw will shutoff. Could be that when hot, the metals will touch without pressing the switch?

[Muddy42]

49 minutes ago, 1d10t said:

For the carb cleaner, thats a no go, I already had air leak problems and replaced head gasket since then, doesn't seem to be anymore leaks.

From what is happening (saw will just cut out instantly, as if it was turned off rather than flooded/leaned out and will also instantly start back if starter rope is pulled - no difficulty at all) it actually does seem like an electrical issue. This has actually been happening for some years or so I'm told (not my saw) but only when saw is hot.

Also, how sensitive should the kill switch be? It's one of those push down to kill, up and out for choke, up and out and then back to normal position for high idle switches.

Right now the switch needs only be touched and thee saw will shutoff. Could be that when hot, the metals will touch without pressing the switch?

 

Yes that sounds slightly different from your original explanation.

- Can you examine the kill switch for issues with the cover off? A small bit of metal may be bent out of place. - Can you the disconnect the master switch and start the saw?  When you do this, obviously take care and you need to block the air intake to kill the saw afterwards.  I wouldn't expect a lose electrical connection issue to only happen when the saw is hot - vibrations and movement would have a more immediate effect.

 

When you replaced the cylinder gasket, you should have pressure and vac tested the saw.  If you the electrical tests above fail, I would check all of the rubber parts (inlet boot, fuel line, impulse line) then pressure and vac test the whole cylinder. Also while you are at it check the piston isn't scored.  Air leaks can manifest themselves in weird ways and this is the only way to be sure.  I would do this test before spending money on an old saw.  

 

[1d10t]

I vac tested the saw with the intake boot off because I didnt have a way to block off strato and main ports well enough, but the test seemed fine except the gasket. I also replaced impulse and return lines along with the primer bulb (had issues with fuel too).

The cylinder had no scoring yesterday, since the saw was run hard for couple hours for at least 3 days since I swapped the piston, I'd assume there'd be scoring if there was an air leak present. I'll try to just disconnect the off switch somehow and run it like that for a bit and see if it has shutoff issues again.

[1d10t]

I only checked for scoring on exhaust side though.

Also, the saw now starts great every time even right after shutoff.

Cold start is like 3 pulls with choke on, then 1 pull most of the time.

Right after shutoff issue it's always 1 pull so I assume it's not flooding?
If there was scoring I assume it also wouldn't start at all when hot. 

[Muddy42]

15 minutes ago, 1d10t said:

I only checked for scoring on exhaust side though.

Also, the saw now starts great every time even right after shutoff.

Cold start is like 3 pulls with choke on, then 1 pull most of the time.

Right after shutoff issue it's always 1 pull so I assume it's not flooding?
If there was scoring I assume it also wouldn't start at all when hot. 

 

not necessarily, one of my saws is really badly scored but has compression and starts fine.  Id isolate the kill switch next as above.

[1d10t]

So I checked out the wires and as you can see in the picture, the edge of the top fin is actually damaged due to spark plug cable chafing on it. The cable itself was chafed almost (but not quite) down to the wire. I suppose it could be causing a misfire when hot and pressed to the cylinder?

I have put some heat resistant insulator tape on it and will see if it fixes the issue.

Is it safe to cut a part of the top fin off to prevent future chafing or will it trigger overheating problems?

The rest of the cable is chaffed almost to the wire in other places too (clips that hold it), but there is only plastic around elsewhere.

[Muddy42]

2 hours ago, 1d10t said:

So I checked out the wires and as you can see in the picture, the edge of the top fin is actually damaged due to spark plug cable chafing on it. The cable itself was chafed almost (but not quite) down to the wire. I suppose it could be causing a misfire when hot and pressed to the cylinder?

I have put some heat resistant insulator tape on it and will see if it fixes the issue.

Is it safe to cut a part of the top fin off to prevent future chafing or will it trigger overheating problems?

The rest of the cable is chaffed almost to the wire in other places too (clips that hold it), but there is only plastic around elsewhere.

 

 

Interesting, you certainly seem to be chasing new problems around this saw! Is this a wind up?

 

Firstly, the cylinder metal is harder than the spark plug cable, so that metal damage is caused by something else.  Incidentally is this an aftermarket cylinder or original?   If the parts are original, you should not need to consider removing metal to get the cable to fit.  Something is not right here.  Is there any text or markings on the cylinder? Could this saw be a mishmash of parts.

 

If the cylinder matches and the tape causes the issue to go away, replace the cable (it must have been shorting to the cylinder) and just make sure you always route the cable correctly in future.  Maybe once the cable was mis-routed causing this damage.

[1d10t]

As far as I know that's the original cylinder. It was replaced this year because the original had stripped spark plug thread, but the replacement turned out to be kinda crappy and so we just rethreaded this one and put a bigger spark plug in. Otherwise everything except fuel lines, gas and air filter, primer bulb, piston and gasket is original.

As for top damage, I don't think there is anything else that could've caused it other than spark plug cable. The cover basically squishes the cable to the cylinder.

The shutoff issue was happening for couple years now.

[1d10t]

It is kinda weird though, spark plug cable is chafed in at least 5 points, both old fuel lines were also chafed almost through in several places... The saw is old but it's not like it was used through the year every year... I know it was used for about 3 months in 2014 (several hours every day) but otherwise it's on average of 1-2 months a year and not every day of those either. Certainly not enough to explain all this damage? Maybe these molded lines are just too soft.

[Muddy42]

I stand what I said before something doesn't seem right here or different parts have been used.  Regarding fuel lines they normally perish long before any damage.  Were the fuel lines replaced with generic pipe of a wider diameter maybe?

 

Did the extra insulation fix the dying issue?