Petrol lawnmower basics
 

I know this is rather the wrong time of year for this, but...

About two months ago I bought a secondhand rotary petrol lawnmower since I
was fed up with the landlord-supplied Flymo with 2" plastic blades. It
seems to be a cheap generic engine-on-a-shell type - I don't see a brand
name. It came with a petrol can, but I forgot to ask about oil.

It worked when I saw it, and when I used it to mow the front lawn, and then
it kept stopping. Noticed there wasn't much petrol in it, so filled it up
with what I assume is unleaded from the can (the seller said he'd give me
the can as he couldn't be bothered to put it in his car). Now it's still
refusing to start. With a few priming pumps I can get it to run for about
1-3 seconds before it dies.

I probably need some oil in there... what oil and what ratio? I'm guessing
it's two stroke since it's pretty basic - but how do I check? Will I have
damaged anything by running it without oil? Now it's refusing to start - so
any tips on getting the oil into the system? Anything else that might go
wrong to a recently-working machine, or that I might be doing silly with it?

I suppose I could strip it down at some point, but that sounds a bit too
energetic for the moment. Meanwhile up until the last week or two the grass
has kept growing :(

Thanks
Theo

Petrol lawnmower basics
 

On 04 Nov 2006 17:24:10 +0000 (GMT), Theo Markettos wrote:

Noticed there wasn't much petrol in it, so filled it up with what I
assume is unleaded from the can

Do you know how old that fuel is? Unleaded goes "off" if stored for afew
months in a non-vapour proof container. Many cheap plastic petrol "cans"
aren't particulary vapour proof.

With a few priming pumps I can get it to run for about 1-3 seconds
before it dies.

Could be blocked jet(s), filter or passageways within the carb.

I probably need some oil in there... what oil and what ratio? I'm
guessing it's two stroke since it's pretty basic - but how do I check?

Is there a oil filler/dipstick anywhere. My guess for a lawnmower engine
to be a four stroke unless it's *very* old.

Will I have damaged anything by running it without oil?

Look for that dipstick and see if you have run it without oil...

Anything else that might go wrong to a recently-working machine, or
that I might be doing silly with it?

Has it a manual choke?

Firstly I'd check the oil level (but that is probably OK) then take the
plug out and check it's appearance, condition and gap. Next have a look
at the carb and fuel filter and swap the old fuel for fresh.

--
Cheers
Dave. pam is missing e-mail

Petrol lawnmower basics
 

Dave Liquorice wrote:
Do you know how old that fuel is? Unleaded goes "off" if stored for afew
months in a non-vapour proof container. Many cheap plastic petrol "cans"
aren't particulary vapour proof.

No I don't. It's probably worth replacing it anyway. Would it be safe to
put the excess in the car? (Otherwise I can't think how I'd dispose of it)

With a few priming pumps I can get it to run for about 1-3 seconds
before it dies.

Could be blocked jet(s), filter or passageways within the carb.

I probably need some oil in there... what oil and what ratio? I'm
guessing it's two stroke since it's pretty basic - but how do I check?

Is there a oil filler/dipstick anywhere. My guess for a lawnmower engine
to be a four stroke unless it's *very* old.

Will I have damaged anything by running it without oil?

Look for that dipstick and see if you have run it without oil...

OK, will do. I didn't see any oil filler or dipstick on the top - possibly
there's something accessible from the side/underneath that I've missed.

Has it a manual choke?

Not a manual choke as seen on a car (or if there is I haven't spotted it).
There's a throttle lever which has 'on' and 'off' but it's cable-linked so
it's possible to throttle it back a bit. I'm not sure that would be
possible in the 1-3s before it dies.

Firstly I'd check the oil level (but that is probably OK) then take the
plug out and check it's appearance, condition and gap. Next have a look
at the carb and fuel filter and swap the old fuel for fresh.

Right, will have a look as soon as I get a chance.

Thanks for the advice,
Theo

Petrol lawnmower basics
 

On 07 Nov 2006 11:22:59 +0000 (GMT), Theo Markettos wrote:

No I don't. It's probably worth replacing it anyway. Would it be safe
to put the excess in the car?

Yes, less than a gallon of stale fuel isn't going to be a problem with a
cars petrol tank more than half full. I doubt it would be a problem
almost empty.

(Otherwise I can't think how I'd dispose of it)

If you don't value your eyebrows it burns well. B-) WHUMPFFF!!!

OK, will do. I didn't see any oil filler or dipstick on the top -
possibly there's something accessible from the side/underneath that
I've missed.

Mighht just be a overflow type filler plastic plug low down. Drains tend
to be a square headed plug right on the bottom edge of the engine
casting.

--
Cheers
Dave. pam is missing e-mail

Petrol lawnmower basics
 

Theo Markettos wrote:

It worked when I saw it, and when I used it to mow the front lawn, and then
it kept stopping. Noticed there wasn't much petrol in it, so filled it up
with what I assume is unleaded from the can (the seller said he'd give me
the can as he couldn't be bothered to put it in his car). Now it's still
refusing to start. With a few priming pumps I can get it to run for about
1-3 seconds before it dies.



Make sure the ignition is on and the fuel inlet is open if there is
one. Sounds like maybe it needs choking for a cold start. If there is
no choke then I'd be surprised but try closing off some of the air
intake or adjust the fuel mixture to be richer. Some carb cleaner down
the inlet often works magic too.

Post a pic somewhere (not here) and someone might recognise it.

Petrol lawnmower basics
 

"Theo Markettos" wrote ...
I know this is rather the wrong time of year for this, but...

About two months ago I bought a secondhand rotary petrol lawnmower since I
was fed up with the landlord-supplied Flymo with 2" plastic blades. It
seems to be a cheap generic engine-on-a-shell type - I don't see a brand
name. It came with a petrol can, but I forgot to ask about oil.

It worked when I saw it, and when I used it to mow the front lawn, and
then
it kept stopping. Noticed there wasn't much petrol in it, so filled it up
with what I assume is unleaded from the can (the seller said he'd give me
the can as he couldn't be bothered to put it in his car). Now it's still
refusing to start. With a few priming pumps I can get it to run for about
1-3 seconds before it dies.

I probably need some oil in there... what oil and what ratio? I'm
guessing
it's two stroke since it's pretty basic - but how do I check? Will I have
damaged anything by running it without oil? Now it's refusing to start -
so
any tips on getting the oil into the system? Anything else that might go
wrong to a recently-working machine, or that I might be doing silly with
it?

I suppose I could strip it down at some point, but that sounds a bit too
energetic for the moment. Meanwhile up until the last week or two the
grass
has kept growing :(


Sounds like fuel starvation caused by dirty carb, dirty petrol filter, dirty
petrol tank, carb float not floating any more but stuck.

The engine on top should have a name on it, normally Briggs & Stratton (4
stroke) or Tecumseh (either) or if it's a more expensive mower a Honda (4
stroke). If it doesn't say B & S or Honda it's more than likely a Tecumseh
probably with another name on it though.
Take a look at the following and see if you can see your engine, then look
for instructions and troubleshooting, you may even be able to download a
manual.
http://www.briggsandstratton.com/dis...sp?DocID=65888
http://www.tecumseh.com/engines.htm
http://world.honda.com/power/

My guess is it just needs a service, if it's a 4 stroke then carb' cleaned
out, and if dirty then petrol tank cleaned out *, then check/change... new
plug, new oil, air filter, if it's a 2 stroke then everything but the oil.
* look also for a petrol filter, it may be blocked with crud too.

--
Regards
Bob H
17mls W. of London.UK

Petrol lawnmower basics
 

Bob Hobden wrote:
Sounds like fuel starvation caused by dirty carb, dirty petrol filter,
dirty petrol tank, carb float not floating any more but stuck.

Took out the spark plug and it was indeed covered in soot, and the air
filter was filthy too. Cleaned both of those as best I could and replaced,
didn't have much difference. I'll see if I can replace the fuel - just need
to find a funnel. I discovered it was four stroke (it even says on top,
d'oh) and there was a small oil filler cap hidden in the muck - seemed to
have oil in it.

The engine on top should have a name on it, normally Briggs & Stratton (4
stroke) or Tecumseh (either) or if it's a more expensive mower a Honda (4
stroke). If it doesn't say B & S or Honda it's more than likely a Tecumseh
probably with another name on it though.
Take a look at the following and see if you can see your engine, then look
for instructions and troubleshooting, you may even be able to download a
manual.

Tecumseh rings a bell - I'd have spotted if it was the other two. I'll have
a look on the site to see if I can find any instructions.

My guess is it just needs a service, if it's a 4 stroke then carb' cleaned
out, and if dirty then petrol tank cleaned out *, then check/change... new
plug, new oil, air filter, if it's a 2 stroke then everything but the oil.
* look also for a petrol filter, it may be blocked with crud too.

Are such things easily accessible (have found the oil, the petrol, the air
filter and the spark plug orifices) or is it usually a 'unscrew every bolt
you can find' job?

Thanks, I'm beginning to understand how the thing works now :)

Theo

Petrol lawnmower basics
 

Martin wrote:
Did you try to get a spark and succeed?

I think so... fired on the pull-cord and then died after 2 or 3s

Are the plugs wet after you have tried but failed to start the engine?

Is the engine flooded

Pass... I'll check next time I have it out. First I have to acquire some
fresh fuel for it.

Theo

Petrol lawnmower basics
 

"Theo Markettos" wrote after
Bob Hobden replied
Sounds like fuel starvation caused by dirty carb, dirty petrol filter,
dirty petrol tank, carb float not floating any more but stuck.

Took out the spark plug and it was indeed covered in soot, and the air
filter was filthy too. Cleaned both of those as best I could and
replaced,
didn't have much difference. I'll see if I can replace the fuel - just
need
to find a funnel. I discovered it was four stroke (it even says on top,
d'oh) and there was a small oil filler cap hidden in the muck - seemed to
have oil in it.

Two further things to try...
1. Try to start it and then remove the plug, if it's very wet then you
haven't got a petrol starvation problem, quite the opposite. If it's still
totally dry the fuel starvation idea is confirmed.

2. Remove the plug and rest it on the side of the engine so the screw bit
touches metal, connect to plug lead and try starting again and see if there
is a nice blue spark across the little gap. If not you have an electrical
problem.


The engine on top should have a name on it, normally Briggs & Stratton (4
stroke) or Tecumseh (either) or if it's a more expensive mower a Honda (4
stroke). If it doesn't say B & S or Honda it's more than likely a
Tecumseh
probably with another name on it though.
Take a look at the following and see if you can see your engine, then
look
for instructions and troubleshooting, you may even be able to download a
manual.

Tecumseh rings a bell - I'd have spotted if it was the other two. I'll
have
a look on the site to see if I can find any instructions.

Their main UK spares place is not far from me in Commercial Road, Staines.

My guess is it just needs a service, if it's a 4 stroke then carb'
cleaned
out, and if dirty then petrol tank cleaned out *, then check/change...
new
plug, new oil, air filter, if it's a 2 stroke then everything but the
oil.
* look also for a petrol filter, it may be blocked with crud too.

Are such things easily accessible (have found the oil, the petrol, the air
filter and the spark plug orifices) or is it usually a 'unscrew every bolt
you can find' job?

Not always. I think you can download a Manual from the Tecumseh web site,
worth a look.
I still think the main contender is that the carburettor is blocked/ full of
crud and simply needs taking apart (carefully in a clean area) and cleaning
(float chamber & jet).
If you damage the paper gasket then carefully cut a new cardboard one from a
cereal packet and make sure you clean the metal surfaces of any bits of the
old one. These tiny carbs can be a fiddly to work on so do take it somewhere
clean and well lit so you can see what you are doing, and treat it carefully
they have very fine tolerances inside.

--
Regards
Bob H
17mls W. of London.UK