Snow blower backfires and stalls as soon as it is put under load

[Red Squirrel]

I have a fairly new Ariens Compact 24 snowblower and recently it started to act up. I start it normally on choke, then let it run a bit then slowly bring it off choke (if I do it too fast it stalls) and it will run fine. But as soon as it starts to eat into any decent amount of snow it will back fire then completely die. Does not give too much warning but I can sometimes manage to recover if I disengage the self propulsion and auger fast enough.

I don't really have a warm place to work on it since my garage is not insulated, so I'll probably end up getting it serviced if it's anything involved, but wondering if it might be something really simple. What would be the first thing to check? I'm thinking the carb. Maybe take it apart and clean it? If I can remove it, then I can just bring it in the house and work on it there and spray it with carb cleaner and stuff.

Anything I can do to also flush out the fuel system, like anything I can add to the fuel, and then just let it run through? I'm using premium ethanol free gas, but the first time I got it I did not know any better and used regular. So I'm leaning towards the carb being gummed up.

I will check it in a few days when I'm off but open to any suggestions of stuff I can check. Considering getting it serviced would probably cost several hundred (I would need a place that can come pick it up as I don't have a truck) I might just buy a propane heater and have it blow directly on me, then I can just work on it in the garage.

 

[boomerang]

Take a look at the color of the spark plug to get an idea if it is running lean or rich. While it's out check for a good strong spark.

If that checks out, try moving snow with the choke half on and see if you get the same behavior. If the mixture is too lean, this will fatten it up. If it runs better under load it points to the carb. Most don't have mixture screws anymore so a disassembly and thorough cleaning is in order. A rebuild kit may be needed if reusing the bowl gasket cannot be done.

Next I would check the flywheel key. If it's sheared the timing could be off enough to start but not allow it to run under load.

 

[Fanatical Meat]

I agree with Boomer, sounds like the spark plug is the first place to check. I'd just replace it and see what happens.
If the gas has been in it for a ton of time, I'd just drain the gas that is in it and put new fresh gas into it. I'd go regular gas assuming premium is not required.

 

[Raizinman]

Sounds like you didn't prep the fuel system at the end of winter and your carb is gummed up. Very common with snow blowers and mowers.

 

[C1]

Classic fuel issue (too lean and that's also why the backfire).

If you have a carburetor that has a flexible diaphragm, then replace that along with cleaning the rest of the carb and filter.

Otherwise, you'll need to clean the carburetor jets and any filters.

To test that Im right, if you can, just before applying a load on the motor, turn up the choke (say to 1/8 or 1/4) & see what happens. If it runs stronger with choke than without, that confirms the direction of the advice.

 

[Red Squirrel]

Thanks for the tips, I'm off tomorrow so think I'll buy a propane heater so I can work in the garage and not freeze my hands off, and I'll get to work and start with spark plug, did not even think of that.

As for "sumerizing" what is the best way to deal with prepping the fuel system? I usually just turn the fuel valve off and let it run dry but is there something better I should do?

Hopefully I don't need any parts since stores here are weird, they stop selling winter stuff in like January despite it being the peak of winter. I have carb cleaner so I'll start with cleaning everything and hope for the best.

 

[Fanatical Meat]

Thanks for the tips, I'm off tomorrow so think I'll buy a propane heater so I can work in the garage and not freeze my hands off, and I'll get to work and start with spark plug, did not even think of that.

As for "sumerizing" what is the best way to deal with prepping the fuel system? I usually just turn the fuel valve off and let it run dry but is there something better I should do?

Hopefully I don't need any parts since stores here are weird, they stop selling winter stuff in like January despite it being the peak of winter. I have carb cleaner so I'll start with cleaning everything and hope for the best.

I'd try the lazy route first.
Drain existing gas
Add new gas with a small amount of carb cleaner in it
try to start it and let some new gas get into everything

 

[Red Squirrel]

I'd try the lazy route first.
Drain existing gas
Add new gas with a small amount of carb cleaner in it
try to start it and let some new gas get into everything

Actually I was wondering if I could do that. Suppose it's worth a shot, just was not sure if it's something that's bad for the engine or if the carb cleaner is basically made for that. The current fuel that's in there now is ethanol free premium but guess it would not hurt to get new gas too, it's from last year. I also put stabilizer in it last year as well. The first time I just used regular gas though as I did not know any better so it could very well be gummed from that gas.

 

[C1]

If you have a carburetor that employs a flexible diaphragm then do not use carb cleaner as that will damage it. (If in the past you've used such cleaner then that's probably why your engine is "hosed".)

If you use carb cleaner, then ChemTool with B-12 is the one to use.

 

[Red Squirrel]

Did not get a chance to play with it today as I'm still recovering from night shift so by the time I got up and had erands to be at all the places that sell propane were closed. I did try the snow blower on half choke and it still stalls, now it pretty much stalls as soon as the auger comes on while before it would run the auger fine it would just stall once it starts eating snow. I'll probably end up having to get a carb rebuild kit. Hopefully I can find propane tomorrow so I can start to work on it and at least open and clean everything as a start. I will pay someone to come pick it up and service it before I work on it in -20's.

 

[Paperdoc]

Engines like this typically have a device that automatically adjusts the carb for load changes, rather like an automatic throttle. The simple ones I've seen are like a small damper vane in the path of air flow into the carb, and this is linked to a throttle adjustment on the fuel flow to the carb. The mechanism is lightly spring-loaded. I believe the idea is that if the engine slows down due to an increase in load, the slower air flow will cause the throttle to open slightly so the engine can speed up again. I know on my snowblower any sudden change in snow load will cause a very brief engine slow-down followed by a return to normal speed, unless the load gets really heavy. That's when I stop and shift to a slower forward speed gear.

Maybe you can check whether your system has something like this. If so, does it move freely or is it seized? A little oil there might help. Also check whether the spring in the mechanism is broken or detached.

 

[Red Squirrel]

Started to work on it but even with the propane heater I bought it was just too cold on the hands to be working on it, and it's basically a torch so did not want to put it any closer to me or the snowblower. It looks like I really need to get deep in there to actually get at any of the parts. After taking off 2 separate casings off I still could not get to much. Seems you need a special socket that is deep so you can fit it over to remove the spark plug, I was hoping to at least check that but no luck. It's really deep in there so you can't use a wrench or anything. I did not want to get any deeper into it given I was on the verge of frost bite. Some times are just worth paying someone else, and think that's what I'm going to do in this case. I just need to find somewhere that will actually come pick it up so I don't have to screw around trying to find someone with a truck and ramps. It's probably something easy, it's just that when you don't have a proper environment or proper tools it makes it harder.

Whatever the issue is won't clear itself up easily either, I tried to run it idle and even idle it starts to backfire after a while. I was hoping that now that I have good fuel in it, it would start to run ok but it's probably gummed up from previous bad fuel.

 

[boomerang]

Engines like this typically have a device that automatically adjusts the carb for load changes, rather like an automatic throttle. The simple ones I've seen are like a small damper vane in the path of air flow into the carb, and this is linked to a throttle adjustment on the fuel flow to the carb. The mechanism is lightly spring-loaded. I believe the idea is that if the engine slows down due to an increase in load, the slower air flow will cause the throttle to open slightly so the engine can speed up again. I know on my snowblower any sudden change in snow load will cause a very brief engine slow-down followed by a return to normal speed, unless the load gets really heavy. That's when I stop and shift to a slower forward speed gear.

Maybe you can check whether your system has something like this. If so, does it move freely or is it seized? A little oil there might help. Also check whether the spring in the mechanism is broken or detached.

For informational purposes, what you're describing is called a governor.

 

[mindless1]

My snow blower merely vibrated loose the carb attachment bolts so it had a vac leak at the base of the carb. REALLY glad I didn't have to work through the jigsaw puzzle that is disassembling it enough to get the carb off, just tightened the bolts and was fixed.

 

[Red Squirrel]

Got it back, been on night shifts so did not get a chance to try it yet, but resolution is that the pet cock was too small (lol) and they drilled the hole bigger. I googled this (lol again) and it looks like that is the fuel shut off valve? That's random, I hope that was really the problem but seems odd it would only start to be an issue now. They did check everything else though so I presume they cleaned it all at same time, hopefully.

Will try it tomorrow as I have a foot or so of snow in my driveway from not bothering to shovel knowing that I just have to wait till my snow blower is fixed.

Either way hopefully next time there's an issue I will have insulated and added heat to my garage so I can try to fix it myself, but this particular thing would probably have been the last thing I'd even think of checking.

Re-reading, it looks like they changed the spark plug too.

 

[C1]

I wouldnt be LOL so soon.

An obvious question is, "if the pet cock was indigenously too small, then how did the motor ever run satisfactorily in the first place, like when it was new?"

Or is all this again, really a matter of cleaning throughout shellac build up from old fuel deposits? (Fuel tanks get really bad from old fuel drying out in them and fuels using alcohol are particularly destructive on rubber such as fuel line hoses & flexible carburetor diaphragms. Often fuel tanks have an inside coating that begins to disintegrate when alcohol additive fuels sit in them unused months on end.)

 

[Red Squirrel]

Yeah that's what I'm thinking too, I still need to call them just to ask for more details. It just seems odd it would require a modification for a problem that is new.

Used it today, it ran fine, but at one point it started to stall, but it's hard to tell what the fuel level is so I put more fuel in it but it was dark so I only put like maybe half a litre, then it ran, but then it started to run funny again but was able to finish the job. When I was done I brought it in the garage so I can see properly and filled it up more, so next time if it stalls I know I really do have a problem. I'm hoping it's just that, but it seems fishy considering I had already filled it not that long ago. But it could be they drained it all to work on it, which is fine as I want to get through this fuel so I can buy fresher fuel. This is ethanol free premium but from last year. I had put a stabilizer in it.

I'm also wondering if I should run it once or twice a week during the summer months. I usually just run it with the fuel valve off and let it run out but maybe I should do that but once a week, or at least until the tank is empty. Or is it actually better to let the tank full with stabilizer so that there's less evaporation of fuel?

 

[C1]

Here are general guidelines:

- Try to use fuels that dont have alcohol additive (because such fuels can be difficult on fuel & carburetor components/systems; particularly in small engines.). If you must use an alcohol added fuel, then that's still okay, but dont let such fuel sit unused all season in a gas tank/carburetor system.

- It is always been stated that with autos in cold months, keep gas tanks full as that helps prevent moisture forming in the tank & hence the possibility of both rust and ice formation.

If you arent using alcohol added fuel, then just keep the tank on the full side as that will help to keep moisture formation down.

If the machine is to not be used for long periods of time or stored, then drain fuel from all systems (ie, gas tank & carb).

If your machine continues to give you problems, then when warm weather comes pull the carb down for inspection
& cleaning. What you find inside of it could disclose to you what you need to know (eg, clogged because of particles coming from damaged gas tank liner/coating; found this to be the case with my B&S lawn mower so had to replace the fuel tank).

 

[ch33zw1z]

Good tips. I use star tron to combat ethanol in fuel. If I dont, the gas goes "bad" in a month or so

 

[Red Squirrel]

Yeah I use ethanol free but first time I used it I didn't know any better and just used regular gas. Now I use ethanol free premium.