Problem with new briggs & Stratton 40

[zikkimalambo]

Hi All,

I bought a new Hayter Hawk mower last year which came with a Briggs and Stratton 40 engine (4 stroke). Auto Choke and a govenor instead of a throttle.

I will cut a long story short, but it has never been a very good runner, it has been running very rich, fouling the plug and now refuses to start at all.

Unfortunately whille trying to figure out what was wrong I took the top cover off while it was running and this hit the flywheel/fan as it was coming off and broke a couple of the fan blades. I don't think this has affected the way it runs, but the manufacturers or their agents might consider it to breach the warranty terms :=((

It seems like it has been running with full choke, but I can't see any choke mechanism. Previous threads speak of a carb where the choke is shut by a spring and opened by vacum. There is what looks to be a vacum connection to the carb (pipe about 1/4" bore) which connects to the carb (to the bowl under the air filter) I can't see any way this can act as a choke though. The connections on this seem sloppy so it's possible it's not getting the necessary suck, also I put my finger over the end while the mower was running and couldn't feel any "pull". (Don't know if i would though??)

I've spoken to the supplier (Hilliers - Large garden centre/nursery) - "We don't have a service dept, contact Horace Fuller for warranty claims".

Horace Fuller "Probably because you are using last years fuel - we could take a look, but it's unlikely to be covered by the warranty"

I did run a tank full of new fuel through, but it got no better and has now stopped altogether.

I also emailed Hayter a couple of days back and got an automated reply saying they would be in touch soon.

I am dischuffed! The previous mower had a Briggs and Stratton with a manual choke and throttle which ran great with just the occasional oil change for about 20 years. I only got rid of it as it didn't have a grass box.

Questions.......

Anyone know what the problem might be? how to fix it?

Also how should I proceed with the supplier/manufacturer/agent?

[Phil Jones]

My Briggs and Stratton mower wouldn't go after coming out of winter storage. It started but then ran rough and eventually died, after that it wouldn't start. The problem with mine was a torn diaphragm in the carb. The man in the mower shop sold me a new one(£2.82) and now it runs as well as ever. He also told me not to store the mower over winter with petrol still in the carb as this is what weakens the diaphragm.

[zikkimalambo]

Is that the very thin thing between the carb and the petrol tank?

I couldn't get a new one this weekend, but had a look at the old one and it seems to be intact :=3D((

[Phil Jones]

That's the part! It only needs to be a pinhole to affect the performance.

Phil J> My Briggs and Stratton mower wouldn't go after coming out of winter > storage.

Is that the very thin thing between the carb and the petrol tank?

I couldn't get a new one this weekend, but had a look at the old one and it seems to be intact :=((

[The Natural Philosopher]

Ive had B & S for years and never paid any attention to laying them up for the winter.

I did have a big problem when I laid one up for 2 years tho. Battery was totally flat and the old petrol in it really didn't want to fire up...

I bought a new battery, and drained as much old fuel as I could, and refilled with new....after it got started i put the old petrol back in..it ran OK ish diluted about 50/50 with new.

In general if these things are getting enough fuel, and a spark, they will at least start.

Check the choke is working, and if possible drain the carb and tank and clean any jets, and refill with new fuel. Should fire up allright.

Rough running sounds like water or dirt in the fuel. Or a very rich mixture..when it did start, did it run smoky blue? Or run in bursts, or just sound like it wanted to tear its guts out it was so irregular?

I forgot which Briggs it was, and whether it had a motor start or pull start..

[zikkimalambo]

Push mower with pull start .

Hayter eventually answered my email and arranged for one of their dealers to take a look at it. Here is what he found for those who come Googling after

He checked the gasket mentioned above, and despite the fact that it has a bit of a bulge in it he siad it didn't look too bad. He replaced it with a (flat) new one, but although he managed to start the mower, it still didn't run right.

He said ti could be a dud coil, spark plug, or else the keyway had gone on the flywheel. He checked the flywhel which was fine, and then replaced the plug.

The machine then ran fine.

He reconnecd the plug had probably been dud since new. he reconned the ones that Brigs and Stratton fit aren't up to much.

I had intended to replace the plug and gasket myself last weekend, but when I wasn't able to get the gasket I didn't bother getting the plug.

Oh well, I saved a few quid, as he siad he would send the bill to Hayter.

He said a couple of other things, the carb is one piece plastic and has no jets or float. The aforementioned gasket kind of flutters like a heart valve in order to supply the fuel. Also it has no choke as such

9though I think it somehow supplies a richer mixture when it's at low revs (ie hasn't started).

He reconned that they are usualy very reliable, though some customers machines seem to require a new gasket each season, while others don't.

- Perhaps it's a split between those who follow the manufacturers instructions not so store the machine with petrol in, and those who don't.

He also said not to tip the machine over on it's right hand side (petrol tank side) as that results in the contents of the sump going into the carb!