Any ideas - petrol strimmer motor stops when off choke

[kingandy2nd]

I have a McCullough strimmer with a husquava motor.

First time trying to use it this year, admittedly with some 40:1 fuel from last year. It starts and runs ok when on choke, but as soon a you switch it to run it dies.

https://youtube.com/shorts/99cdeQkelXM?feature=share

When I move the camera I’m flicking the switch down to turn the choke off.

Any ideas how to fix?

thanks all
Andy

 

[Tigercubrider]

Speaking as a motor biker, old fuel is always an issue. It goes off in six weeks.
Modern fuel also clogs jets when it goes off.

I'd pop to Halfords and get a can of carb cleaner.
Wear eye protection as it's nasty if it blows back.
You might need to poke a very very fine wire (guitar strings are good) through any orrifices and then blow through with carb cleaner and an extension tube.

Make extensive notes of all the things like screw turn numbers and any needle positions.
A garden engine may be quite simple

 

[kingandy2nd]

Thanks.

I thought fuel, but then thought again as it’s running on the choke fine...

Will drain it and get new fuel before starting to take apart.

Cheers

 

[Burnerman]

Before you get stuck in, try to identify the carb (possibly Zama) and get a diaphragm and gasket set.....ethanol fuel is really destroying them.
John

 

[kingandy2nd]

New fuel and 2 stroke, after draining the old stuff. Sprayed carb cleaner in, but still the same.

@Burnerman doesnt seem to be any name on the carb.

Think it’s going in the skip as I don’t really have time to faff around if changing diaphragms etc is a bit job

after new fuel and carb cleaner:

https://youtube.com/shorts/hXslSGTooyE?feature=share

 

[Burnerman]

It looks like a Walbro WYK series carb, replacements are available from the likes of GHS Ltd if you want.
John

 

[JohnD]

It starts and runs ok when on choke, but as soon a you switch it to run it dies.

I have known that happen on bikes where the carbs have a starting jet, a slow-running jet, and a main jet.

The slow-running jet, being smallest, is prone to clog with residue when it dries out over winter.

The bike will start on the starter jet, and drive on the main jet, but cuts out when you close the throttle. Or, when cold, it's ticking over and you release the "choke" (if it is actually a jet and not a flap)

Older bikes and mowers with a manual fuel tap were easier to run dry before parking up. This is especially important with petroil engines.

I don't know if your machine uses a similar design.

 

[Harry Bloomfield]

Blocked jet!

You might be able to clear it by...

Get it running, get it on max revs, turn choke off and slap your hand over air intake. You may need to remove the air cleaner to be able to do that. Idea is to create maximum vacuum on the obstructed jet, to suck the obstruction through.

 

[lostinthelight]

The obstruction is more than likely going to be a coating of gum lining the drilling which wont suck out or be removed by by hopeful spraying carb cleaner in the air intake ,well not NIMO anyway.
With that carb where you can see the brass part on top, in the central hole there may be a tiny plug hiding a slotted screw which adjusts the main needle jet.
Winding this anticlockwise raises it which , may richen the mixture enough to make it run without choke.
Edit: Cant quite remember whether its clock or anticlock now as its a long time since I did one

 

[JohnD]

it will be difficult to clear it without dismantling.

air does not pass through the jet so spaying the air intake will not clean it.

poking wire is deprecated because it will scrape the precise measurement of the jet.

If you can adjust it wider by moving the needle back as @lostinthelight suggests, it may get going, and the passage of clean fuel might remove the gum over time. you would then need to readjust it as it will be running rich.

next year, if you can, empty out all but an eggcupfull of fuel and run it until it runs out, then store it upside down so fuel cannot run into the float chamber.

 

[kingandy2nd]

Thanks everyone. I do always run it dry before winter and store without fuel.

Strangely after a few more times of trying it, it started up without any other tinkering.

It would run for a few mins, and the die. It would then no longer start on the choke, but would fire in the second (neutral) setting.

Not ideal as it’s running rough, but it ran enough to get the edges done.

thanks for all the suggestions, I will tinker some more when time allows.

cheers
Andy

 

[Nige F]

In the off season ( winter ) leave the carb soaking in methylated spirit (ideally a large closed jar) next spring all the gum will be gone - worked for me