Petrol strimmer won't start

[GliderRider]

Sometimes an ignition coil will give a spark when the spark plug is at atmospheric pressure, but won't in the increased pressure inside the cylinder. If you can put another plug in series with the first when is installed in the head, then you can be reasonably sure it is sparking.
Spark plugs in two stroke engines are prone to getting a build up of carbon which causes tracking between the two electrodes, so its definitely worth trying a new spark plug in the engine. Before fitting it though, with the tank empty give a good number of pulls on the starter cord to clear any stale fuel from the crankcase.
Fresh fuel is essential. As a rule, any that has been in a can for more than thirty days is suspect.

[DonkeyApple]

Jonboy_t said:

It does sound like it wants to go with some fuel dropped straight in. I’ve had the plug out and it sparks to a screwdriver perfectly too so definitely power to the plug.

I keep a can of this for getting all the garden equipment going when it decides to take a holiday: WYNNS AIR INTAKE & CARBURETTOR CLEANER

For years I fannied about taking carbs apart, checking fuel lines and generally completely over thinking things. Now I just spray a whole slug of this into the air intake and the motor always fires and runs of that quite happily. After a few more slugs it starts mixing in with the old fuel and the engine is getting warmer and it begins to run on its own. I’ll often find that after a long winter the mix screw might need a little turn in either direction to keep the engine running and hey presto all is good.

It’s a bodgetastic can to have on the shelf. Saves hours of potential faffing every spring.

[S6PNJ]

DonkeyApple said:

I keep a can of WYNNS AIR INTAKE & CARBURETTOR CLEANER

I use Holts Cold Start - made for the job after all!

[Jonboy_t]

Cheers for the advice chaps

As nothing more than an enthusiastic novice when it comes to oily bits, should I expect fuel to be actually making it through the carb into the pot when I pull the go cord? Everything from the tank to the bulb has fuel flowing nicely, but it just seems to get no further than the bulb so I’m not sure if there’s a carb problem or the carb is ok and it’s not being dragged in by vacuum?

[DonkeyApple]

S6PNJ said:

DonkeyApple said:

I keep a can of WYNNS AIR INTAKE & CARBURETTOR CLEANER

I use Holts Cold Start - made for the job after all!

I discovered the Wynn product when I went looking for this but had no immediate joy:

[GliderRider]

Jonboy_t said:

Cheers for the advice chaps

As nothing more than an enthusiastic novice when it comes to oily bits, should I expect fuel to be actually making it through the carb into the pot when I pull the go cord? Everything from the tank to the bulb has fuel flowing nicely, but it just seems to get no further than the bulb so I’m not sure if there’s a carb problem or the carb is ok and it’s not being dragged in by vacuum?

The fuel should be geting through the carb, otherwise the engine won't run. As others have said though, it is very easy for the small jets to get gummed up. If the H and L (High and Low) needles can be opened a turn or so, then there is more chance of the fresh fuel getting past the gum. Once the engine starts running, the fuel will dissolve the gum and the needles can be returned to their original positions. A Ryobi will probably need one of these tools to adjust the 'tamperproof needles':

https://www.ebay.co.uk/itm/Carburetor-Carb-Adjusti...

[dickymint]

First things first (not wanting to teach you how to suck eggs) is your starting procedure correct?

1. Prime - you can't over prime so a good ten pushes.
2. Choke on full
3. Kill switch off
4. Keep pulling till you get ANY signs of life
5. Choke off
6. Should then start within half a dozen pulls.

As others have said spray/pour petrol or Easy Start directly into pot and repeat above. If still not firing try a brand new plug.

If it wont fire with a good spark and fuel in the pot i'd say it's almost certainly a compression problem. Anything below 70psi it won start and time to throw it away!!

PS. Ryobis really are ste

[Jambo85]

GliderRider said:

The fuel should be geting through the carb, otherwise the engine won't run. As others have said though, it is very easy for the small jets to get gummed up.

Indeed - spent a bit of time yesterday afternoon coaxing my mower into its first start of the year. Took the bowl off the bottom of the carb and a skoosh of brake cleaner in about it, reassemble and all good.

I usually forget to the do the right thing in autumn and shut off the fuel and then run it til the carb is dry. Makes life a lot easier come spring. The manuals all say to pop a teaspoon of oil in the cylinder as well but have never been bothered with that...

[austinsmirk]

I've gone through 2 Ryobi multi tools now. utter garbage. last one ended up with a scored barrel and piston. parts would have cost more than buying new as such.

Aldi- don't laugh- were selling a full multi tool system for £130 recently. so I'm trying that currently. mainly based on the fact it has a 3 yr warrenty. At least if it all fails, I can get my money back with ease. The ryobi ones failed just inside 12 mths- so got a replacement. then failed outside of 12 mths. so stuck with a broken motor now.

I wish I were a far richer PH'r. It'd be a stilh instead.

but like everyone says, they are new fuel sensitive and also need a lot of endless adjustment. Has yours got the "pacman" bespoke tool fitting. meaning none of a normal mechanics tools even fit the damn idle screws.

[dickymint]

austinsmirk said:

I've gone through 2 Ryobi multi tools now. utter garbage. last one ended up with a scored barrel and piston. parts would have cost more than buying new as such.

Aldi- don't laugh- were selling a full multi tool system for £130 recently. so I'm trying that currently. mainly based on the fact it has a 3 yr warrenty. At least if it all fails, I can get my money back with ease. The ryobi ones failed just inside 12 mths- so got a replacement. then failed outside of 12 mths. so stuck with a broken motor now.

I wish I were a far richer PH'r. It'd be a stilh instead.

but like everyone says, they are new fuel sensitive and also need a lot of endless adjustment. Has yours got the "pacman" bespoke tool fitting. meaning none of a normal mechanics tools even fit the damn idle screws.

Totally agree with you about Ryobi ste but don't blame the manufacturers for the "pacman" fittings - blame this new era of green eco loonatics trying to save the planet and our chiwldren. They fit them to stop us from tuning them to work properly

[GliderRider]

dickymint said:

If it wont fire with a good spark and fuel in the pot i'd say it's almost certainly a compression problem. Anything below 70psi it won start and time to throw it away!!

Low compression can be due to the rings being stuck in their grooves with carbon. Take the exhaust off, and if the bore isn't scored it could be worth taking the cylinder off and freeing the rings. It really depends on how much you value your time.

Another trick with a reluctant engine is to take the recoil starter off, and with a suitably sized socket in an electric drill and a squirt of fuel mix down the carb, spin it over as fast as the drill will allow. It certainly saves the arm muscles and is the best chance of getting it going. Flywheel magnets can lose their magnetic field with time, but this can be rejuvenated with use.

Edited by GliderRider on Monday 30th April 22:43