2 stroke Hyundai Strimmer - Dies with any revs

[Gad-Westy]

My 2 stroke Hyundai strimmer seems to have an issue. It starts okay on the choke. I can leave it idling like that for a while. I can rev is a bit with the slider still on choke but it starts to struggle and if you keep the revs up it dies. If I open the choke it dies. Basically it only seems happy idling on the choke.

This problem actually started last year but I put off doing anything about it and used our little electric unit for a while. I did clean the fuel tank, lines and carburetor over winter but that doesn't seem to have made any difference. Any thoughts?

[b14]

It's a bit of a cliche but it's likely old fuel. I had exactly the same problem with my 2 stroke strimmer, it would start and idle but wouldn't rev. I thought it was something to do with the centrifugal clutch but turned out no, just needed new fresh fuel from the pump.

[Griffith4ever]

Gad-Westy said:

My 2 stroke Hyundai strimmer seems to have an issue. It starts okay on the choke. I can leave it idling like that for a while. I can rev is a bit with the slider still on choke but it starts to struggle and if you keep the revs up it dies. If I open the choke it dies. Basically it only seems happy idling on the choke.

This problem actually started last year but I put off doing anything about it and used our little electric unit for a while. I did clean the fuel tank, lines and carburetor over winter but that doesn't seem to have made any difference. Any thoughts?

I've repaired , over the last few years.

- strimmer
- mower
- mower
- childs quad
- chainsaw

With the strimmer, I tried solving the carb issue by servicing it. Wasted my time.

Buy a new carb.

- strimmer - new carb
- mower new carb new "coil"
- mower new carb
- quad new carb
- chainsaw new carb

It's just not worth messing about. Carbs are £5 - £10 max. Ebay / Amazon. It's almost always the carb gummed up - one of the jets not working as it should. Whether "old fuel" does that, no idea, but I'll tell you this. I never pour the old fuel away, I just replace the carb and they run fine from then on.

Carb refurbish kits are more expensive than a new Chinese carb. They are also rediculously easy to replace, and often come with all the gaskets, a new spark plug, air filter , etc

[Pando99]

I stripped the carb on my strimmer after the same issues and found a tiny orifice that had a mesh in it and it was blocked with dirt - this was stopping fuel getting through.

Might be similar

[Convert]

Had a similar problem with a 2 stoke Titan a few years ago. Removed the spark arrestor screen from the exhaust ( it was blocked with carbon). Fitted exhaust back on without the screen and it revs like new.

[dhutch]

Get a Stihl.

[Gad-Westy]

Thanks all. Much appreciated. I had another quick look over the existing carb today. Couldn't see anything obvious but did waft some carb cleaner around. Tried fresh fuel. No change. I've just ordered £11.28's worth of Chinese carburation. Hopefully that will have it sorted.

[RustyNissanPrairie]

Some little 2 stroke engines have a diaphragm in the carb that uses the impulses to pump fuel, these get a tiny perforation and then the engine doesn't work properly.

Rebuild kit will sort them.

[Metric Max]

If the new carb doesn't sort it there are two things that you might like to try.

The plastic fuel pipe doesn't like Ethanol and goes hard and can doform internally restricting fuel flow. New fuel pipe is cheap on ebay for a selection pack of different sizes.

I have two 2 stroke engines where the bolts holding the cylinder barrel became slightly loose. This resulted in fuel coming out from the joint but also allowing air to be sucked in which caused me problems similar to yours, This was not helped by the manufacturer only putting 2 bolts rather than 4, IMO not good engineering.
Not too difficult to sort out once you figure how to access the bolt heads/ nuts

[Griffith4ever]

Metric Max said:

If the new carb doesn't sort it there are two things that you might like to try.

The plastic fuel pipe doesn't like Ethanol and goes hard and can doform internally restricting fuel flow. New fuel pipe is cheap on ebay for a selection pack of different sizes.

I have two 2 stroke engines where the bolts holding the cylinder barrel became slightly loose. This resulted in fuel coming out from the joint but also allowing air to be sucked in which caused me problems similar to yours, This was not helped by the manufacturer only putting 2 bolts rather than 4, IMO not good engineering.
Not too difficult to sort out once you figure how to access the bolt heads/ nuts

I had a strimmer that would not hold high revs unless I held the choke lever very slightly "in". The physical mechanism was not stopping/resting where it should. I replaced the carb. Air leaks are indeed a common problem to simple engines.

[DonkeyApple]

Gad-Westy said:

Thanks all. Much appreciated. I had another quick look over the existing carb today. Couldn't see anything obvious but did waft some carb cleaner around. Tried fresh fuel. No change. I've just ordered £11.28's worth of Chinese carburation. Hopefully that will have it sorted.

Almost certainly the logical fix as alluded to by an earlier poster. Once the carb has begun fannying about then it's a toss of a coin as to whether you can clean out the cause and a £10 replacement is all too often the quick and simple fix.

My go to routine is to firstly only use Aspen on these little two strokes then if an issue crops up I'll fire the engine up on carb cleaner and if that doesn't work it's off to eBay.

[Gad-Westy]

Thanks for the further replies folks.

Slightly embarrassing confession but I'm not sure it changes the outcome.

I was actually starting it unchoked now that I've looked properly at the label!

So basically it will not start on choke even from stone cold. But will start unchoked but will not stay running with revs. And it will die immediately if I choke it.

Seems like it's still likely a carb issue and I shall wait for the replacement and hopefully fix it but I'm slightly confused as to why it won't run at all choked.

[Ojm1]

But a multipack of garden equipment carb screwdrivers off Amazon, and go a quarter turn out on the mixture screw. Mine looked like a Pac-Man. If no change then another 8th / 1/4 👍

[Griffith4ever]

Gad-Westy said:

Thanks for the further replies folks.

Slightly embarrassing confession but I'm not sure it changes the outcome.

I was actually starting it unchoked now that I've looked properly at the label!

So basically it will not start on choke even from stone cold. But will start unchoked but will not stay running with revs. And it will die immediately if I choke it.

Seems like it's still likely a carb issue and I shall wait for the replacement and hopefully fix it but I'm slightly confused as to why it won't run at all choked.

Blocked jets or weather. A lot of small 2 strokes won't start on choke after barely one try. My Stihl chainsaw won't (starts on one pull off-choke in this weather, won't start on-choke). So don't get too obsessed with the choke-factor.

[Bessacarr]

Putting carb in an ultrasonic cleaner often helps.
The hyundai fires temporarily on choke then pull again without choke and they generally run . If carb is clean .

[DonkeyApple]

Gad-Westy said:

Thanks for the further replies folks.

Slightly embarrassing confession but I'm not sure it changes the outcome.

I was actually starting it unchoked now that I've looked properly at the label!

So basically it will not start on choke even from stone cold. But will start unchoked but will not stay running with revs. And it will die immediately if I choke it.

Seems like it's still likely a carb issue and I shall wait for the replacement and hopefully fix it but I'm slightly confused as to why it won't run at all choked.

Sounds like too much fuel. What does the plug look like?

Could be a filthy air filter so might be worth trying it removed if the plug looks mucky and once cleaned and gapped. If not then a jet may be gummed open but running some carb cleaner through normally sorts that. The other non carb cause can be too much oil in he mix.

[Gad-Westy]

Thanks folks. I'll take another look later. I'm pretty confident the fuel is fine. Since this saga began, I'd flushed with clean fuel at least twice and have been careful to follow the correct mix. I'll take a look at the plug though. I've been putting it off as it's very easy to damage the HT cable when removing it but I'll bite the bullet and take a look later. The plug was replaced and gapped last year though when I first encountered this issue. Could be a bit fouled up now though I suppose.

[dhutch]

Always worth checking the plug in anytime, but especially a two stoke. If you do it after a few fail starta you should see it if wet it not too.

You can also stick in the ht lea, touch it against the head, and in a darken room pull it over and check what the spark looks like.

[DonkeyApple]

Gad-Westy said:

Thanks folks. I'll take another look later. I'm pretty confident the fuel is fine. Since this saga began, I'd flushed with clean fuel at least twice and have been careful to follow the correct mix. I'll take a look at the plug though. I've been putting it off as it's very easy to damage the HT cable when removing it but I'll bite the bullet and take a look later. The plug was replaced and gapped last year though when I first encountered this issue. Could be a bit fouled up now though I suppose.

2 stroke problem solving is addictive. . There's a perverse pleasure from the bds when they decide to go into Agatha Christie mode.

It is nearly always the carb but it's still worth checking everything else if only to confirm that it's the carb.

Once plug is checked and air filter removed if symptoms persist then my last check is to wind down the two carb settings to min and see if I can slowly dial back in the idle setting to get it running on tickover and then dial up the throttle setting.

If that works then what you normally subsequently find is that after it's been working for a while it's gone lean because the gumming in the carb has cleared.

[chrisch77]

It’s worth also stating the obvious, that your fuel needs to be both fresh and accurately mixed fro the right oil ratio for your specific engine. If you have a habit of just winging it with the 2 stroke mixture then you will get starting and running issues, so get a proper graduated mixing bottle.

I had this with a friend’s strimmer last week, he brought it over because he hadn’t been able to get it started and all it needed was some accurate 40:1 mix and the plug gap reducing to spec.