Petrol Mower

[Nick]

I have an old Mountfield Empress mower here with a 3.5hp Briggs & Stratton

4-stroke engine.

The problem is that it will not start when the weather is cool to cold (i.e. now).

In spring and summer it is fine, although leaving it out in the sunshine for half an hour before starting it definitely helps.

Once it is running it is fine.

Have done all the usual things, plug, air filter, even stripped and cleaned the carb, but no change.

Tried warming up the cylinder head with a 3kW fan heater but this didn't seem to help, so maybe it's to do with the temperature of the air being pulled into the engine.

Any ideas please?

[Tim Lamb]

In message , Nick writes

Mine still starts OK:-)

Is fully travelling the speed control actually engaging the choke?

Sometimes fiddling with the cable where it exits the outer helps.

[The Natural Philosopher]

auto choke stuffed or needs a new plug

[Davey]

It might possibly be losing the spark if it's damp. Try starting it when it's dark, then you might see sparks where they aren't supposed to be. Could be the spark plug wire insulation breaking down.

Otherwise, I agree about the choke not functioning properly.

I have an old car engine that behaves similarly, so don't feel left out. A fully charged battery makes all the difference.

[Nick]

Yes, it is. The choke is definitely working. In warm weather I don't use the choke; it seems to flood easily.

[Michael Chare]

I think that modern petrol engines tend to start more easily because they have electronic ignition. This make me wonder whether you could upgrade the ignition. Another thing that may help is to use the Briggs & Stratton fuel additive which is intended to prevent the build up of gunge in the fuel system, particular after long periods of no use.

[Tough Guy no. 1265]

My electric mower has never failed to start.

[NY]

Does it have a spring-retracting pull-cord starter? Those never seem to get the engine turning over fast enough or long enough before you reach the end of the rope.

What I used to do with my dad's petrol power (in the days before he bought a petrol hover mower) if it failed to start fairly quickly on the pull cord and after I'd dosed up the carburettor using the tickler knob, was to fasten a hard rubber sanding disc in the electric drill and, running the drill in its lowest gear, touch that on the rotating shaft that led to the clutch for powering the blade. Get the engine turning over nice and fast and constantly to create a draught on the inlet side to suck air (and therefore fuel) through the carburettor. The mower always started using this improvised starter motor!

[Tim Lamb]

In message , Michael Chare writes

Well if you are going to spend money, buy some easy start. Don't tell the sniffers but I think it is pretty much ether.

[Tim+]

Often a sign of a choked air filter.

Tim

[F Murtz]

[Michael Chare]

I used to have something like that which I used to help start a Penta outboard engine. IIRC it did help as it made the engine fire once or twice if the petrol failed ignite.

[Another John]

Yes - I was going to say that. I use Easy Start every time on my little, old, mower that I use for the lawn and fiddly bits (I use a ride-on for the main grass). Easy Start is easier than buggering about with an engine for hour after hour in order to "fix it" (IME they're never fixed properly). Prime the engine, take off the air filter, couple of seconds squirt of ES into the carb, filter back on: starts first time. Once the engine's hot it always starts, whenever it's switched off during the mowing session, with a half-pull of the cord.

When I said all the above a few months ago in response to a similar enquiry, someone (was it TNP?) suggested that's it's even easier and cheaper to squirt gas from your blowtorch into the carb. (*Unlit* blowtorch, comprende?)

John

[Tim Lamb]

In message , Another John writes

Not easy to hold the blow torch while pulling the start cord:-) The easy start takes a few seconds to vaporize.

[Huge]

C'est moi. Although I got the idea from someone here. Works an absolute treat.

[Nick]

Yes it does. Although it seems to give the engine a good enough spin in warm weather to start it.

[www.GymRatZ.co.uk]

Wash out with de-greaser and re-oil with a splash of clean engine oil, squeeze out excess and re-fit.

Job done.

:)

[Another John]

Sorry for the mis-attributi> Not easy to hold the blow torch while pulling the start cord:-) The easy

Ah. Oh. I didn't realise that the technique involves doing that --I assumed the gas would stay in the carb long enough to do the trick (like ES does).

Anyway: Nick's had plenty to think about here in his thread!

John

[The Natural Philosopher]

certainly wasnt me.

However poor cold starting can also be worn rings or valves.

Compression test will confirm.

[Nick]

The air filter is new.