My Husqvarna 45 chainsaw won't start only if the trigger is pulled

Question

I have a Husqvarna 45 chainsaw and it won't start only if the trigger is pulled, and if i release it , the chainsaw stop's. Any suggestions?

Answer 1

The carburetor likely just needs cleaning out and re-adjusting.

You can get a build-up of deposits on the jets which can cause issues like this.

I would first try buying a tin of carb cleaner spray and give the intake of the carb a few good soakings to see if that helps. You will need to take the air filter cover off the tool to get access to the air intake. Pull the throttle to open the butterfly valve to allow the spray inside.

There are videos on youtube for cleaning chainsaw carbs.

Answer 2

Carburetor cleaning is the way to fix the situation, but the problem will repeat.

It's caused by poor quality gasoline. And by "poor", I mean 99.9% of the gasoline sold, all of the gasoline used by cars for example.

In carbureted engines and engines lacking catalytic converter, you should really be using "small engine gasoline" / "alkylate gasoline". It's almost pure isooctane. If you know how octane rating is defined, isooctane is the "good stuff" and N-heptane is the "bad stuff". A fuel with 98 octane rating for example behaves equally than 98% isooctane and 2% N-heptane mixture would behave.

It costs more, but small engines are used so little that this isn't a problem. Also the exhaust gases are non-carcinogenic, if you use your chainsaw a lot (for example professional forestry worker) you will probably get cancer from the exhaust fumes if you don't use alkylate gasoline. Also the exhaust of alkylate gasoline stinks less.

Normal gasoline has very poor storage properties. You shouldn't store it more than a month. It will gum up your carburetor if you leave it in your equipment. One solution is to drain the fuel completely out, including from the carburetor (may require using the carburetor drain screw if your equipment has it, if not then tough luck). Another solution is to drain as much fuel with a hand siphon as you can and then run the equipment until it dies of fuel starvation.

But with alkylate gasoline, you can leave your equipment with gasoline in it for 5 years and it will still start exactly as well as it would if it was fueled yesterday.

Just remember to mix two-stroke oil if using it in two-stroke engines (like in chainsaws). You may also find premixed alkylate gasoline for sale that has already the two-stroke oil added.

If you cannot find alkylate gasoline, a far poorer solution could be fuel stabilizer. It still won't fix all of the problems of poor quality gasoline, for example ethanol can damage some rubber seals even if you use fuel stabilizer, but could be of some help as a backup solution.