Top tips for keeping your petrol strimmer running like a ‘Rolls Royce’
- Make sure the fuel you have in the tank is fresh and not from three years ago (it goes off)
- Keep the spark plug gap set within the manufacturer’s tolerances
- Lubricate all moving parts lightly with a generic spray oil each time you use the strimmer

Someone got in touch with a strimmer that would not start. Anything that involves moving parts and petrol always gets my attention, so I accepted the challenge. Once in the workshop, I tried to start it using the pull cord and as predicted, it wouldn’t run, not even a cough. A little bit of carb cleaner sprayed in to the barrel, a pull of the starter cord and the engine did fire, suggesting that the engine could run. More analysis was required.
The strimmer had not been started for many years, so the first job was to remove the old fuel from the tank as old fuel goes off after a while. The engine on this strimmer is a two-stroke design, so the special two-stroke oil must be pre-mixed with the fuel in the right proportion before re-filling the tank.
While sorting the fuel out, I noticed the first fault. Both flow and return fuel pipes were cracked and one had come apart in the fuel tank, meaning that no fuel would flow to the carburettor. No fuel, no work.
To start most petrol strimmers, mowers and chainsaws from cold, a petrol primer pump is usually used to fill the carburettor with the right amount of fuel and this one was no different, but in this case, the pump was cracked.
After fitting some new fuel lines, a fuel filter and primer pump, the engine fired up and ran well again, ready for more garden work. See slide show.
Cost of replacement: £80 and up. Cost of repair: £7.53 plus my time and custard creams.

Hi hope anyone can help I’m doing a repair on my qualcast strimmer replacing the pull cord any ideas how I get it of cheers davie
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Maybe send me a picture by getting in touch using the contact us link. I might be able to help.
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Hi, any link where to buy a new carburettor for grass trimmer model cdb30a? thanks
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Hi, sorry I don’t know. Have you tried eBay – maybe some generic parts that will fit?
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No but I’ve got one you can buy and it’s in excellent condition
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Hi there. You wouldn’t know where I can source a qualcast strimmer battery charger, CGT18LA1?
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Hi Chris, I’ve seen some on eBay
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how do you change fuel pipe on a qualcast strimmer there is no grommet two pipes going in to fuel tank
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Hi Alex, the two pipes are an interference fit to the tank… not elegant, but that’s how they seem to be.
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Can they be replaced or can you get a grommit to fit ???
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Hi Alex, it’s best to replace these pipes with fresh new ones as they degrade with age… new ones are tricky, but possible to fit. Have a look on ebay and measure the pipes carefully before ordering.
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Many thanks
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Hi, I’ve just inherited a similar Qualcast Petrol Strimmer. Replaced the broken primer bulb, put in fresh fuel, and managed to start it, and run it for a while at idle, but when I try to throttle up, it dies. The fuel lines are old, but seem to work, and I will change the fuel filter, but the problem seems to be connected to the throttle. Any pointers as to where the problem is likely to be?
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Hi Dominic, it could be the diaphragm within the carburetor. They are susceptible to splitting. Might be worth fitting a service spare.
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Thanks – I stripped down and cleaned the carburettor, and the diaphragm was fine. Still won’t run for more than 5 seconds. The only thing I haven’t tried is a new spark plug – could that be it?
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Hi Dominic, thanks for getting in touch. I would check the hoses as they can break down. Use fresh petrol too. Good luck.
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Hello, I’m having difficulty with the strimmer head in as much as the strim line will not extend when tapped on the ground.
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Apologies, I pressed the wrong key !! I was going to ask, is there a diagrammatic view of the strimmer head showing the assembly ?
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Hi Rod, sorry I don’t have one.
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Hello, I’m having difficulty with the strimmer head in as much as the strim line will not extend when tapped on the ground.
Okay, thanks for the reply, I guess I’ll have to get the grey matter active lol
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Sounds like a take it apart on the bench job
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Hi
What size fuel pipe is it and what type ? Can’t seem to get official spares as they are out of stock
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Hi Tim, I can’t remember to be honest. Something like 4-5mm internal diameter rings a bell. I think I bought a multi pack.
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Re: Qualcast CDB30A fuel line
Just been to the DIY store and bought 50cm pack of 2.4mm internal, which also has printed on it 4.8mm external – this is the closest I could find to my measurements of the old tube which was in bad state. Will attempt repair tomorrow (9 June 22) and will post success or failure, or problems asap.
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Good luck with it. Fingers crossed.
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I have a fuel tank leak and can’t find tank replacement anywhere.. any ideas..thanks
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Sorry, I don’t. You could try a silicone patch of some type, that resists fuel ingress.
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Hi my qualcast strummer real has a lot of movement (up and down) where it attaches to shaft. The person I bought it off said a new spool will fix the problem but I’m not sure it will
Can anyone offer any advice for this please
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Very difficult to say without seeing it
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Hi I have a Parker petrol strimmer that won’t start it’s under warranty but they have told me to get this repaired myself but anything that is due to normal service and wear and tear they wont pay for it but I leave in Newark Nottinghamshire and can’t find anyone close to me to get this repaired can you help me
Regards
Mr jarman
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Hi Michael,hmm could be a struggle I guess because of the distance. Also, I’m not doing garden equipment at the moment (lack of space). Macara in goring, Worthing might be able to help.
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Hi Michael, I’m not sure to be honest. I’d persist with the retailer… sounds like there’s more to do there.
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Hi, do you know what replacement carburetor would work. Would the generic one of Amazon fit? Thanks
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how do you release a primer bubble that caved in on a qualcast
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Hi Kevin, I can’t remember to be honest, it was a while ago. I think it clipped in and was held with a plate.
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How do you open the casing in a Qualquest strimmer to access a broken starter cord. I have taken out all the casing screws but can’t see how it opens.
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Hi there. I can’t remember to be honest. There are probably a few additional security clips to gently lever apart.
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