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?

     There's no backfiring B&S OHV here at the moment to try the following on but it might work. 

     Get the machine to it's lowest idle then punch the primer to choke it off.  That might work.  It depends on what exactly is causing the backfiring. 

     The new B&S OHV designs backfire and the older properly running L head Tecumsehs never did.  The older usual reasons for backfiring don't seem to apply.  Your dealer suspected a very likely valve issue so replaced the crank.  Nothing changed.  Good running to spec B&S designs just backfire. 

     One possibility for the backfiring might be the design of the idle circuit and high speed for better compliance with the EPA.  The backfiring happens when the rpm is low and engine shut off i.e. coil grounded. 

    The engine is still spinning and the venturi speed slowed way down.   The carb then would be transitioning from high speed to the idle circuit or just on the idle circuit.  The new design may be dribbling the last gas from the high speed or pulling from the low which is just starting again to get enough gas to the head for a backfire with the spark grounded.  It's just the right amount of air, at the right flow and gas get to the head to fire.   Modifying that may make a change. 

    The air flow can be changed by putting on full choke.   That will also richen the mix.  The amount of gas can also be further changed by a few stiff pumps on the primer for a flooding condition.   A lot of gas will go to the head, less air and what gets there will be less atomized than usual.  The flooding might just work and quickly dry in the head and not interfere with a quick restart.   

i have a 2012 Ariens deluxe 30 with the 342CC engine.  Mine will backfire every single time i idle down from full open to idle.  Even trying to slowly return the throttle would almost alwasy result in a backfire.  I called my dealer and they call Ariens, they said they know of the problem and the ignition coil needs to be changed.

I have a 16hp briggs on an lawn tractor and to help stop this type of problem they installed a solenoid where the bowl nut normally goes and a plunger plugs the jet as soon as the ignition is turned off to stop any additional fuel from entering the engine.  Personally I find it to be a pain in the ass.

Carl

carlb wrote:

Lots of new engines have those fuel shutoff solenoids now. Yet another thing that has to be tested whenever you have a problem.

#$&$^&$% you, EPA.

This isn't even a new engine.  Its a 1992 briggs and stratton i/c gold made in the USA before they epa really had much to do with these small engines.  I am in the process of rebuilding this engine because the rings finally wore out after 20 years of very very hard use.  The rest of the engine inside looks like new  the bore looked great but a little glazed,  honed the cylinder put a new ring set on and new gaskets and it should be good to go.  I will be removing the solenoid and just put a regular bowl nut in its place because when i pulled the terminal off the bottom of the solenoid the tang on the solenoid broke off and I have bowl nuts laying around and the solenoid is around 40 dollars and not worth replacing.  I always throttle my OPE down before turning it off and don't expect to have a problem.  If it pops out of the exhaust when i shut it off i really don't care the muffler is pointing out of the front of the tractor anyway.

I had a Toro lawn tractor with a B&S engine and it does the same thing, always backfire during shut down.  The effect can be lessened by throttling down before shutting off, but it does so still.  Very annoying.

My other Toro push mower has a B&S side valve engine.  It rarely backfires.  However, it is difficult to restart once the engine is hot.

Both engines have been reliable so far, not knocking on B&S engines, but they are annoying engines that leaves me not too fond of them.  Seems like B&S just thinks they're good enough to leave them alone and not take care of these things.

My Ariens w/Briggs OHV engine did the same thing when new.  Just have to throttle down PAINFULLY slowly.  And always throttle down before shutoff.   It seemed to do it less and less as time (seasons) went on, or maybe I just have the procedure down by now! 

Depending on what year,engine costs, and size. engines may come with a main jet solenoid that cuts all fuel off at shutdown,   this is to reduce exaust and stop backfires.  Most or all need a battery to run the solenoid when starting.  I imagine that the solenoid can be found or modified to fit about any engine made by Briggs with a fuel bowl..

Good Luck,

Friiy

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