Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I purchased a brand new Ariens Platinum deluxe 24" snowblower in October of 2009.  I paid $2000 Canadian with tax.  A few weeks ago, I used the machine for the first time to clear about 5 cm of snow.  Unit started up well and removed the snow.  Then, when I went to shut down the unit, it backfired and two flames/sparks came out of the exhuast.  I went to start the machine up again and it wouldn't start even though it had been running for 20 minutes.  So, I opened up the choke, primed the unit and it started.  Upon shutting down, the backfiring happened again and again it wouldn't start.  So, I contacted Ariens.  There response was:
1. Put the throttle down to half, let it idle for about 30 seconds and then shut it down.
I did that and still the backfiring happened.  So back I go to contact Ariens.  They tell me to take it back to the dealer.  I did and they:
1. changed the camshaft
2. started 4 other Ariens machines and they all did the same thing.
3. Contacted Briggs who told them the backfiring is caused by the engine running lean so that they could make it through emission restrictions.  They also told the dealer to tell me not to worry about it.

At this stage, I'm frustrated.  I find it unacceptable to pay $2000 for a machine and have it backfire right from the get go.   Interestingly enough, the dealer had a single stage toro 421 and a powerlite.  Both units come with the 4 stroke Chinese made engine from Loncin.  He started those up and neither one of them backfired.  

I don't understand how Briggs can let this go.

Now, I don't know whether to:
1. Just keep the unit.
2. Push Ariens to do something about the unit.  Ariens uses the snow series Briggs.  I wonder if the Snow Max series does the same thing.
3. Push Ariens to give me my money back.

Any idea/feedback?

my 1986  8hp tecumseh ariens used to backfire on shut down also. by richening up the high speed mixture setting to help cool the combustion temps and idling it down for 20 - 30 sec's before shutdown it doesn't backfire anymore. i would guess that  newer engines with non adjustable mixture settings  are set to run lean from the factory and a cooldown period before turning the engine off would  be the only thing that might prevent backfiring. my 2002 koehler 2 cyl. 18 hp cub cadet lawn tractor will backfire if run hard and not idled before shutdown and i have learned thru the years to idle it down before shut off as well. the exhaust port area in the heads is hot enough to ignite unburned fuel and by idling the engine down it helps reduce temperatures and elliminate backfiring during shutdown.

There are two causes of backfiring in these engines.  One is the lean mixture that they now run due to EPA regulations causing the mufflers to get much hotter than a slightly richer running engine and the fact that raw unburnt fuel is injected into the very hot muffler when the engine is shutoff.   When you turn the key or engine switch off it stops the spark but fuel is still pulled into the engine as it is spinning down and the unburnt fuel is being sent into the muffler and this is what causes the backfire. 

If you have an engine with a fuel shutoff you can first idle the engine down and turn the fuel off.  This will allow the muffler to start to cool being the engine is idling and the engine will shut off on its own when the fuel in the bowl runs out.  This will not allow any unburnt fuel to get into the muffler thus no backfiring should happen.

If you dont have a fuel shutoff idling the engine down for a minute or two before shutting the engine off will also help greatly.

If you don't have an engine with a throttle but you do have a fuel shutoff, shutting off the fuel and letting the engine die due to lack of fuel should also work pretty well.

Carl