I know this is slightly off topic as the engine's in a mower but I
recently bought an ex demo Bolens lawn tractor. It looked imaculate, I
suspect it had never cut any grass. Anyway, it came off eBay for about
1/2 price and worked well so I was happy. It has a 13HP Techumse
engine and replaced an old Sears mower with a B&S that worked well for
many years until the back axle snapped.
Anyway, the new one was put to work and all was wonderful. Then it
began hunting slightly and its 13 horses seemed a little lame. Over
the next few running hours things got worse until it would only run on
full choke. Cleaning the carb and plug only seemed to make matters
worse until it ran no more. Further cleaning of the carb changed
nothing. The engine would only start with my hand covering most of the
carb mouth or with petrol dripping from a brush into said carb mouth.
By now I'd had the carb in bits more times than I can remember and
grudgingly admitted defeat by taking it to my local mower company,
muttering unprintables as I did so.
When I bought the mower, it came without any paperwork except a rather
nondescript receipt. Fortunately that was enough to prove it's date of
purchase so it should be under guarantee.
The agent says it needs a new carb. I suppose at =A365/hr, it's cheaper
than paying them to fiddle with it. Techumse are considering the
warrantee claim but the good news is a new carb is only about =A335. I
assume there's VAT on that but it's still less than I expected. As a
comparison, my smaller mower needed some drive belts. For some reason,
MTD seem to have them made to their own spec. They cost =A330 each! Now
I've got the part Nos, I can get them of the 'net for about 1/3rd
that.
In the meantime, the grass is loving this weather and is growing like
crazy. Does anyone rent out horses or sheep?
John
I know this is slightly off topic as the engine's in a mower but I
recently bought an ex demo Bolens lawn tractor. It looked imaculate, I
suspect it had never cut any grass. Anyway, it came off eBay for about
1/2 price and worked well so I was happy. It has a 13HP Techumse
engine and replaced an old Sears mower with a B&S that worked well for
many years until the back axle snapped.
Anyway, the new one was put to work and all was wonderful. Then it
began hunting slightly and its 13 horses seemed a little lame. Over
the next few running hours things got worse until it would only run on
full choke. Cleaning the carb and plug only seemed to make matters
worse until it ran no more. Further cleaning of the carb changed
nothing. The engine would only start with my hand covering most of the
carb mouth or with petrol dripping from a brush into said carb mouth.
By now I'd had the carb in bits more times than I can remember and
grudgingly admitted defeat by taking it to my local mower company,
muttering unprintables as I did so.
When I bought the mower, it came without any paperwork except a rather
nondescript receipt. Fortunately that was enough to prove it's date of
purchase so it should be under guarantee.
The agent says it needs a new carb. I suppose at £65/hr, it's cheaper
than paying them to fiddle with it. Techumse are considering the
warrantee claim but the good news is a new carb is only about £35. I
assume there's VAT on that but it's still less than I expected. As a
comparison, my smaller mower needed some drive belts. For some reason,
MTD seem to have them made to their own spec. They cost £30 each! Now
I've got the part Nos, I can get them of the 'net for about 1/3rd
that.
In the meantime, the grass is loving this weather and is growing like
crazy. Does anyone rent out horses or sheep?
John
MTD belts are an oddball width from what I remember.
From memory, a standard B-series belt will fit, but it'll slip under load,
wearing out the pulleys as quickly as the belt.
Out of curiousity, where can you get them for a 1/3rd of the normal price?
moray
I know this is slightly off topic as the engine's in a mower but I
recently bought an ex demo Bolens lawn tractor. It looked imaculate, I
suspect it had never cut any grass. Anyway, it came off eBay for about
1/2 price and worked well so I was happy. It has a 13HP Techumse
engine and replaced an old Sears mower with a B&S that worked well for
many years until the back axle snapped.
Anyway, the new one was put to work and all was wonderful. Then it
began hunting slightly and its 13 horses seemed a little lame. Over
the next few running hours things got worse until it would only run on
full choke. Cleaning the carb and plug only seemed to make matters
worse until it ran no more. Further cleaning of the carb changed
nothing. The engine would only start with my hand covering most of the
carb mouth or with petrol dripping from a brush into said carb mouth.
By now I'd had the carb in bits more times than I can remember and
grudgingly admitted defeat by taking it to my local mower company,
muttering unprintables as I did so.
When I bought the mower, it came without any paperwork except a rather
nondescript receipt. Fortunately that was enough to prove it's date of
purchase so it should be under guarantee.
The agent says it needs a new carb. I suppose at £65/hr, it's cheaper
than paying them to fiddle with it. Techumse are considering the
warrantee claim but the good news is a new carb is only about £35. I
assume there's VAT on that but it's still less than I expected. As a
comparison, my smaller mower needed some drive belts. For some reason,
MTD seem to have them made to their own spec. They cost £30 each! Now
I've got the part Nos, I can get them of the 'net for about 1/3rd
that.
In the meantime, the grass is loving this weather and is growing like
crazy. Does anyone rent out horses or sheep?
John
I suppose you checked that the carb was getting plenty of fuel from the tank
and the tank vent was not plugged. There are a lot of new carbs sold but I
have been working on engines for over 60 years and I have probably replaced
less than 5. They do wear out in some areas but if all passages and jets are
clean and if it is properly assembled and installed it will always work. If
there is fuel in the bowl and the passages are open, the venturi will create
enough suction to pull fuel into the airstream.
Strangely enough, I have found that such lean symptoms are sometimes caused
by insufficient ignition energy. Be sure to try a new plug regardless of how
the old one looks and check that you have a good hot spark.
Don Young (USA)
Tecumseh used Carter carbs and another make for some years, but as Don says,
carbs don't normally wear out.
Check that you haven't got grass cuttings in the fuel filter from the tank
(might be in the tap assy)
Tecumseh was a North American Indian, details here:
formatting link
Peter
--
Peter & Rita Forbes
Email: snipped-for-privacy@easynet.co.uk
e:
There's certainly plenty of fuel getting to the carb. The tank vent
was certainly not plugged as cap was off and the tank is clear of
everything but fuel. There's a fair volume of fuel in the float
chamber so if there was a supply problem, the engine should at least
start OK and die when the chamber runs dry. There's no tap to confuse
me either.
The spark and the plug both looked good. As the engine ran OK with
more fuel, I concentrated on the carb but will keep an eye on the
plug. The annoying thing is the engine has only run for about 10
hours! It has all the symptoms of a blocked carb but I've cleaned
everything I can find, many times.
It's really annoying that something as simple as a lawnmower engine is
beating me.
John
I don't think so but I've never really dealt with these.
It's got a normal float chamber and jets. The float chamber's vented
to the inlet side of the carb.
John
Some of these small carburetors have a very small hole thru the side of the
center tube of the body. That is how the gas gets from the float chamber
into the jet tube. These will get plugged and are very difficult to see.
Others have notches at the bottom of the tube. Regardless, check that there
is a way open for gasoline to get freely from the float bowl into the center
of the carburetor to the main jet as that is a common problem. Also check
the float level. Lacking specifications, check that the needle valve closes
when the float is approximately parallel with the bowl flange. Some
carburetors have a small wire clip that pulls the needle open when the float
drops. If this one does check that it is properly installed. Also check that
the float is not dragging on something and is operating the needle freely.
You can check whether the needle is open or closed by blowing into a short
hose attached to the fuel inlet (do not use compressed air).
Hope this helps. (Try a new plug just for fun! I think a rich mixture takes
less spark energy to ignite as I have been fooled by weak ignition and plugs
that looked good but would run only on a rich mixture. It is definitely not
true that any spark at all will ensure ignition.)
Don Young
Don Young
I picked up a lawnmower with a Tecumseh motor from the tip recently -
although a much smaller motor it had a similar problem - it would only
start if I poured petrol in the air intake and it died when that was
exhausted. The problem was the carburettor - the retaining bolt for
the float chamber is drilled and cross drilled to feed the main jet and
was blocked.
I don't know whether this link will help as it only goes up to 11hp
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