On 1/08/2011 9:03 a.m., Jim K wrote:
"Gib wrote in message
...
On 1/08/2011 3:21 a.m., Jim K wrote:
"Gib wrote in message
...
On 31/07/2011 7:46 p.m., Londonman wrote:
It'll stop dead as it's under load of sorts.

These stops can occur under no load.

Electrically, as you say they are simple and if it was an electrical
issue you would have trouble starting every time.

Unless it's intermittent.

Check the carb hasn't come adrift slightly and is sucking air, other
than that it's getting tired.

Everything was screwed down tight. I'm certainly getting tired.

Local mower shop or Ebay source a carb repair kit strip and sort it.
(Item 190556871460 might do the job but you will have to ask them about
your model or search for a kit for yours etc)

Thanks, it's possible that the kit will be available locally, but not
likely, given the age of the mower.

Also source a new air filter and a can of carb cleaner spray and don't
prod around with bits of wire in any ports or jets.

I'm used to working on bike carbs, probably will not do anything stupid.

Change the plug and the oil at the same time. If the plug is fairly
black suspect piston rings, but that's usually after many years of use.

thinking on a bit, when it conks whip the plug out and check for a spark
when someone pulls the starter rope- that will narrow it down to one or
the
other (fuel vs elecs)

I've tested the spark (by myself, which isn't very satisfactory), but not
just after it conks out. The spark is weak.

There no engine number, so I can't use the B&S site to search for a
manual. The only identification on the engine is Classic 3.5 HP.

does this help narrow it down?

http://www.briggsbits.co.uk/acatalog...hp.html#sprint

Jiim K



It doesn't look exactly like that engine. It might have been sold only
in the US (where I bought it). I'm guessing that this is the simplest
(cheapest, nastiest) engine that B&S ever made. The carb, which is
plastic, is simpler than the old 3.5 hp version I've seen online. It
has only one intake tube+gauze filter, instead of the usual two.

I cleaned the carb and petrol tank (neither looked dirty, no sign of
water), checked that the filter was clean (I cleaned it recently),
changed the oil (way overdue), reassembled and ran it. I was able to
make good headway on the lawn until it bogged down on a thick patch -
this is normal. So far it looks OK. If the problem recurs the next
step is to pull the flywheel off and look at the points (and if
necessary the capacitor), since the spark is always weak.

Thanks to all for helpful suggestions.