Petrol strimmer won't start

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Discussion

Jonboy_t

Original Poster:

5,038 posts

184 months

Friday 27th April 2018
quotequote all
Last year, I was given a petrol strimmer (a Ryobi RLT30CES) that my old chap had been using for a few years, but it had given up on life. In my inexperienced mind, everything pointed towards a dodgy carb not allowing fuel through so I've replaced that but it's still not firing at all.

Looking at the carb now (the new one), when I prime it, fuel fills the bulb so the lines are fine, but it's then is pushed back out into the fuel tank and nothing goes into the carb itself. The bulb doesn't lose any fuel if I leave it alone for a day, so again, no leaks there. I've put it all back together and pulled the starter cord which I would have thought should pull fuel through the carb and into the pot, but the piston is dry as a bone and there's no fuel odour at all.

There's spark at the plug and vacuum when I take the plug out and put my thumb over the hole, so that's me out of ideas!

Any thoughts on what else could be causing the lack of 'go'?!!

Tampon

4,637 posts

226 months

Friday 27th April 2018
quotequote all
Jonboy_t said:
Last year, I was given a petrol strimmer (a Ryobi RLT30CES) that my old chap had been using for a few years, but it had given up on life. In my inexperienced mind, everything pointed towards a dodgy carb not allowing fuel through so I've replaced that but it's still not firing at all.

Looking at the carb now (the new one), when I prime it, fuel fills the bulb so the lines are fine, but it's then is pushed back out into the fuel tank and nothing goes into the carb itself. The bulb doesn't lose any fuel if I leave it alone for a day, so again, no leaks there. I've put it all back together and pulled the starter cord which I would have thought should pull fuel through the carb and into the pot, but the piston is dry as a bone and there's no fuel odour at all.

There's spark at the plug and vacuum when I take the plug out and put my thumb over the hole, so that's me out of ideas!

Any thoughts on what else could be causing the lack of 'go'?!!
Try spraying carb cleaner into the carb. Fuel might have varnished in the jets preventing it from getting through, very small holes.



cbmotorsport

3,065 posts

119 months

Friday 27th April 2018
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He's replaced the carb.

Was the carb new or secondhand?

Jonboy_t

Original Poster:

5,038 posts

184 months

Friday 27th April 2018
quotequote all
Yeah, carbs been replaced. As far as I know, it’s totaly new. Certainly no signs of previous gaskets on the faces or anything anyway.

allegro

1,135 posts

205 months

Friday 27th April 2018
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It's a little heath but when I had trouble starting my rotavator after a period of non use I found it helpful to remove the sparkplug and drop a little fuel in the cyclinder.

allegro

1,135 posts

205 months

Friday 27th April 2018
quotequote all
Oh and if you happen to spill a little on or around the machine and it catches fire I found lemonade is a surprisingly good fire extinguisher hehe

motco

15,974 posts

247 months

Friday 27th April 2018
quotequote all
I'm not sure how the transfer valves on these two-strokes work, but in my model aircraft flying days some two-stroke (diesels, but no matter in this case) had reed valves and some rotary valves. Perhaps a valve is leaking and the charge is not getting transferred to the upper part of the cylinder?

Wacky Racer

38,198 posts

248 months

Friday 27th April 2018
quotequote all
allegro said:
Oh and if you happen to spill a little on or around the machine and it catches fire I found lemonade is a surprisingly good fire extinguisher hehe
What a waste of lemonade.

(Unless it was Asda smart price)

CrutyRammers

13,735 posts

199 months

Friday 27th April 2018
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Spraying a bit of fuel into the carburetor mouth might help it start. Fuel hoses can perish. The vacuum hose which goes to the carburetor (if it has one) can perish and collapse, preventing the diaphragm from pumping fuel.
Constantly battling with this kind of thing is why I ditched petrol chainsaws for an electric one. 2 stroked don't like only being used every 6 months.

littlebasher

3,782 posts

172 months

Friday 27th April 2018
quotequote all
Just to eliminate it, try starting with the fuel cap loose / off to make sure that the breather isn't blocked. Else it'll suck nothing through

That and kinked / collapsed fuel lines (cheapo plastic that seems to rot over a single season)

cbmotorsport

3,065 posts

119 months

Friday 27th April 2018
quotequote all
Can recommend an Echo.Great machines.

Jonboy_t

Original Poster:

5,038 posts

184 months

Friday 27th April 2018
quotequote all
I’m 99% positive that it’s not related to the lines as fuel is getting to the bulb perfectly fine. It’s also coming back out of the breather hose into the tank when the bulb is pressed repeatedly. The place it’s not getting to seemingly is the important bit!

I’d rather not ditch it and get a different make or an electric one just yet. It was a freebie to me so a few quid on a carb is more in my price range than a new one! Plus, and this is the stubborn bit in me, I SHOULD be able to fix it so I don’t want to give up on it until it’s diagnosed as terminal!!!

peterperkins

3,152 posts

243 months

Friday 27th April 2018
quotequote all
Does it fire/run a bit with easystart/petrol squirted into the air intake?.

If yes then you know spark is good and it's a fuel/carb problem..

craig1912

3,323 posts

113 months

Friday 27th April 2018
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kapiteinlangzaam said:
Before I opened the thread I knew it would be a Ryobi.

Been there done that.

They are junk. I spent too much money and time trying to revive mine when it randomly died one season.

Throw it away and buy something better.....
I thought a similiar thing- I’ve got one and it’s a tortuous start routine (I sent it back at first as I thought it was broken) but now I know the routine it starts every time.
I have a Ryobi hedge trimmer and in 10 years it has never failed to start. Still on same plug and I never drain the tank over winter- so they aren’t all crap!

wolfracesonic

7,028 posts

128 months

Friday 27th April 2018
quotequote all
cbmotorsport said:
Can recommend an Echo.Great machines.
Great machines.............Great machines..............Great machines.............

motco

15,974 posts

247 months

Friday 27th April 2018
quotequote all
wolfracesonic said:
cbmotorsport said:
Can recommend an Echo.Great machines.
Great machines.............Great machines..............Great machines.............
biggrin

cbmotorsport

3,065 posts

119 months

Friday 27th April 2018
quotequote all
wolfracesonic said:
Great machines.............Great machines..............Great machines.............
Lol.

Jonboy_t

Original Poster:

5,038 posts

184 months

Friday 27th April 2018
quotequote all
cbmotorsport said:
Will take a look at the gaps, cheers. Got a gapping tool somewhere that my grandad left me when he died 15-odd years ago that I thought I’d never got to use!!!

wolfracesonic said:
Great machines.............Great machines..............Great machines.............
biggrin

peterperkins said:
Does it fire/run a bit with easystart/petrol squirted into the air intake?.

If yes then you know spark is good and it's a fuel/carb problem..
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.

alfabeat

1,122 posts

113 months

Friday 27th April 2018
quotequote all
I have had similar problems before and it turned out to be a faulty fuel tank cap. Not letting any air in, so it builds up a vacuum and sucks the fuel back out of the carb. Take the fuel line off the carb and suck the fuel out, make sure it keeps on coming. If not then that could be your problem.