Lawnmower problems!

Soldato
Joined
18 Oct 2002
Posts
9,022
Location
London
Bought a petrol mower about 5 or 6 years ago, maybe a bit more. Used it for a couple of years, then due to a long story.. it wasn't used for about 3 or 4 years.

Last week I got it out of the shed where it'd been sat (nose down I might add), and left it standing flat for a day (incase the oil was sunk around the sparkplug). Next day tried to start it but obviously a no go! So I did the following, baring in mind I'm a complete amateur and know very little...

1. Drained the oil, there was very little as I'd never changed/topped it up since the first year.
2. Drained the petrol that had been sitting in there for a few years.
3. Put new oil in.
4. Put new petrol in.

Pressed the primer button 2 times, and after a bit of work on the pull cord and some very think white smoke, it was a goer! Smoke cleared after 5-10 mins, and managed to do the front/side/back lawns no problem. Probably took 45 minutes in total, lots of stops and starts due to the grass bag being full after a few minutes.

Anyway, now the problem.
Started it up this week, couple of presses on the prime, worked a charm. Did half of the back garden and now it's in a state of chug-chug-chug, like it's about to stall. Often does. Quite low RPM.

So the garden is now in a right state, and looks stupid being half done :D

I've..
- Cleaned the sparkplug, no change.
- Bought a new sparkplug, no change.
- Checked in the oil/dipstick and there is oil.
- More than enough fuel.
- No grass/chaff in the top of the cooling section.
- Opened up the air filter, cleaned out the sponge thing and re-oiled that up. (while I had that off I looked down into the carburettor and the bit I could see was clean and clear).

So basically I've done all the 'simple' stuff (which is about the limit of my knowledge lol). So does anyone have any ideas about what to try next? Or what could be wrong?

The only thing I can think is that the oil I used (which I use in my pug306) is no good. It's 15W40 and in the mower manual it says SAE30? Will this cause the issue? Of chug chug chug... I thought it might be miss-firing (not sure if that's the right word) from a bad sparkplug (that hadn't been changed from day 1) but the new one is no better.

Any ideas or past experience would be great! I'm at a loss and the garden is getting nearer the sky.... :o
 
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There's no choke as such... there's a governor control leaver... but it doesn't appear to be user-moveable, I assume the engine controls it. The springs on it are working fine, and it moves though.

I took the air filter off and then removed the petrol tank/carb combo. Carb was amazingly clean, no gunk at all, tubes were fine. The fuel pipe into the tank looked fine also. Plenty of oily grass around the outside though, but I wiped that off.
Only thing I can think is the fuel is duff. It's probably been in the shed for 2-3 years as well...
So I empted the fuel tank out - why the opening has to be in the centre.. I have no idea. Makes it very hard to tip out the fuel! But after some shaking that came out, fitted it all back together and started it up. Ran for 2 seconds and stopped. Going to wait until I can get to the garage for some new fuel, hopefully that will solve all the problems... Occam's razor and all that...

Thanks again for the tips.
If the new fuel doesn't work I will try cleaning the carb anyway. And trying without the airfilter.
Also, the tank had a few specs of grit on the bottom when it was empty. Literally only a few. Just wondering what the best way for cleaning it out would be? Can I just swill a bit of water around in it a few times, and leave it to air dry?
...I don't want to make matters worse :eek:
 
Bit of an update, the mower works perfectly now!

All I did was take the carb off, clean the outside of it, as the inside was 'like new'! I did blow a bit on it, put it all back together, and it runs perfectly now!
I can only imagine (as said) a tiny spec of grit was stuck in a tube causing it to run badly.

Thanks for the tips guys :) I've learnt from now on I will give it a good service each year.
And also 2-3 year old fuel works fine lol.
 
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