Strimmer Issue

Jasoncmor · 12 Jun 2019 at 23:01

Hi all

Another small issue I have.
I have a cheap 52cc Chinese strimmer that I'm having issues with.

Think it's about 4/5 years old now, it was cheap, but if I can save it that would be great, but not much of a loss if I can't.

The issues are firstly, after use it's as though the fuel tank pressureizes and the fuel fills up the piston chamber, I thought it was the tank cap so I first took out the diaphragm then used another cap off my old strimmer that was fine but didn't seem to fix the problem.
When I came to use it the next time, I'd have to take out the spark plug and empty out the fuel from the piston area as the engine was locked.

After emptying and putting the spark plug back in it ran fine until the next time, it was used often, usually every week in the summer months.

Second problem, the engine revs would start to raise on idle, and then it would also struggle to rev properly and also not rev at the higher end, it would almost bog down.

I thought the carb would be at fault, so as they are cheap, I got a new carb, but there was no change. Tried fiddling with the idle screw and the tuning screw? And still not running any better.

Does anyone have any experience with these kind of machines?

I'm thinking it could be a fuel line issue, but I did replace the lines a few years ago, maybe they need looking at again I don't know.

I need to get it out and have a look but just thought I'd ask if anyone has any suggestions / experience.

Cheers, jason

sja360 · 13 Jun 2019 at 08:02

Do you continue to use the same fuel left over from the previous year/period? I'm sure I read its not ideal leaving it sitting until the next year, best to run the tank dry.

Jasoncmor · 13 Jun 2019 at 09:08

I did used to leave the tank with fuel in, until recently when it started leaking into the piston chamber.
It usually didn't go periods that long without being used to never bothered to drain it, and because of the regular use it got filled up every few runs anyway.

Cheers

pastymuncher · 13 Jun 2019 at 10:47

Are you able to fit a fuel tap to the fuel line, ideally just after the tank?

ron3003 · 13 Jun 2019 at 18:49

Reed valves knackered.

Jasoncmor · 13 Jun 2019 at 19:06

ron3003 said:
Reed valves knackered.

Where abouts are they? And are they easy to replace?

Cheers

Jasoncmor · 13 Jun 2019 at 19:07

pastymuncher said:
Are you able to fit a fuel tap to the fuel line, ideally just after the tank?

I could have a look, it's quite tight but depending on how big the valve is, it could fit.

Cheers

ron3003 · 13 Jun 2019 at 19:24

Jasoncmor said:
Where abouts are they? And are they easy to replace?

Cheers

Sits between the carb and crankcase, something like this

Jasoncmor · 13 Jun 2019 at 21:56

ron3003 said:
Sits between the carb and crankcase, something like this

Cheers mate, when I get a bit of time I'll strip it down and take a look

Jasoncmor · 22 Jun 2019 at 18:23

So I stripped it all down completely, pretty sure I didn't find a reed valve, so not sure if these are supposed to have one or not.

I used the original carb, gave it a bit of a clean, rebuilt it with fresh seals, priming nipple, replaced the fuel lines and fuel filter, and spark plug.

Made up a bottle of 2 stroke mix, with fresh fuel, then it started almost straight away.

It ran the best it's ran in a long time. Not revving up on it's own, not bogging down when trying to rev it up, and fuel pressure not building up in the fuel tank forcing it to flood the piston chamber.

Cheers all

Terminal_Boy · 22 Jun 2019 at 18:36

Good job. The fuel pick up filter that sits in the fuel tank needs changing every couple of years. Air filter is another item to check annually.

Empty the tank out and idle and run the engine at low rpm until the carb is empty before storing it over winter.

Never, ever use any fuel that contains ethanol for garden machinery, especially two stroke stuff.

Always let the engine warm up for a minute or two before using full throttle and remember to keep the throttle pinned wide open when cutting.

Jasoncmor · 23 Jun 2019 at 08:21

Terminal_Boy said:
Good job. The fuel pick up filter that sits in the fuel tank needs changing every couple of years. Air filter is another item to check annually.

Empty the tank out and idle and run the engine at low rpm until the carb is empty before storing it over winter.

Never, ever use any fuel that contains ethanol for garden machinery, especially two stroke stuff.

Always let the engine warm up for a minute or two before using full throttle and remember to keep the throttle pinned wide open when cutting.

Cheers for the advice, it's appreciated

Squid Vicious · 25 Jun 2019 at 07:31

Useful thread - I've got a titan multitool that's having similar issues after sitting over winter.

Looks like a problem with fuel getting to the engine as it can be convinced to start, but then won't rev and will die after a short period of time.

If you take the carb off for cleaning are there any parts that need to be replaced? Thinking gaskets and the like.

Already picked up some carb cleaner and a set of brushes for the jets.

Terminal_Boy · 25 Jun 2019 at 08:08

Clean the air filter and check that any choke mechanism fitted isn’t jammed on.

Ditch the fuel you have in the tank and mix up some fresh using 0% ethanol petrol.

My experience with Stihl 2 stroke powered equipment is that you only need full choke to start on cold (<10°C) days. Above 20°C, using even half choke will flood them if you don’t release it the moment the engine catches.