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

[mojo jojo]

I doubt that any issue with the carb (even autotune) could instantly cut down an engine. I am 99,9% you got problems with the spark. Sudden shut off is always cause by a loss of spark. 

Possible problems...followed by easiest and cheapest to hardest and expensive...

1. spark plug... change it...check your heat range...I believe your spark plug is not original.

2. kill switch

3. cables from coil to spark plug and kill switch

4. coil

 

 

[1d10t]

9 hours ago, mojo jojo said:

I doubt that any issue with the carb (even autotune) could instantly cut down an engine. I am 99,9% you got problems with the spark. Sudden shut off is always cause by a loss of spark. 

Possible problems...followed by easiest and cheapest to hardest and expensive...

1. spark plug... change it...check your heat range...I believe your spark plug is not original.

2. kill switch

3. cables from coil to spark plug and kill switch

4. coil

 

 

Regarding spark plug: the cylinder in the picture (original cylinder) had it's spark plug thread stripped. Bought a new cylinder and the same shutoff issue was still present, but it eventually got a piston ring caught in the rough port edges (twice). Rethreaded the original cylinder for a bigger spark plug after, which is the one in the picture. Had to also grind down the nut on the spark plug to make it possible to tighten.

Since the issue was happening with two cylinders and three different plugs, i can PROBABLY eliminate a spark plug problem.

I'll check out the cables first, then I'll disconnect the kill switch and tape over connectors.

I won't be changing the coil as it's too expensive.

[1d10t]

Worth looking into tank vent too? I did additionally have issues with fuel pumping which wasn't solved by new fuel lines and purge bulb.

Basically sometimes the purge bulb would just stop working and just pump air. 

[adw]

This is a coil, or wiring to it issue, you need to check the earth wire as a said before, the auto tune unit takes its power from the flywheel magnets passing 5he coil, it is very important you have a good earth, the wire is secured at the r/h rear of the cylinder, a single m4 screw, if the screw has come loose it gives all sorts of problems.

[1d10t]

Thanks, will disassemble again. Ground was attached last time I checked. I'm still somewhat hoping it's not the coil as supposedly it should be hard to start too afterwards, but it's one pull start everytime after dying.

[billpierce]

I have a 545 which has siezed. It's a parts saw. Your welcome to buy it for any parts you need. The carb and coil are good for example. 75quid?

[1d10t]

I would but i'm not from UK sadly  probably would cost more than that in postage

EDIT: would be great for the case as well since brake handle mount is broken 🥲

Edited December 1, 2024 by 1d10t

[1d10t]

A bit of an update on this:
First a bit of a backstory: the saw was pinched between tractor and a handle got bent when fairly new.

The handle was replaced and it seems whoever did it, used the wrong screw (too long). It punched through the case (either when being installed or sometime later) and was rubbing on ignition coil as in the picture.

Coil air gap was also tiny (barely enough for normal a4  paper to fit), possibly the coil was being pushed away by the screw and closer to flywheel.

I have now fixed the gap to 0.3 mm and used a shorter screw on this side of the handle and we'll see what happens.