# Wont start - advice wanted



## Yard_oppy (Jan 20, 2021)

Hey guys. Just found this forum. Hoping one of you more knowledgeable people care to chime in on this.
Snow blower info:
*SnowMaster 724 QXE Snowthrower*
212cc, OHV

List of symptoms:
Wont start
Back fires through carb and exhaust (randomly shoots flames out of both.)

Here is what I have done so far:
Checked spark: perfect
Checked compression: 95-100psi 
Fresh gas
Cleaned the carb
Adjusted the valves (.15 inlet, .20 outlet)
Checked the keyway on the flywheel (perfectly intact).

Here is all recent events:
a few weeks ago I changed the oil ready for a winter storm.
Next day I went out and blew some snow and hit a chunk of ice. Engine stalled on me, had a rough time starting again but managed to get it going. 
Parked it for about 3 days and then it wouldn't start. 
I have tried using straight starter fluid, carb clean, brake clean etc to get it to run. Most it does is backfires through carb or exhaust.

My fear is I skipped a few teeth on the cam/ bent the cam and now the timing is way out. 


Any advice before I go opening her up is appreciated. 

Thanks in advance.


----------



## Oneacer (Jan 3, 2011)

If it was running fine as you say, and started your troubles when you whacked the ice, I would not have touched the carburetor or gas route..

In my opinion, since I was not there, I would lean towards the jarred key or something ?

Since you adjusted the valves, you already know about TDC.


----------



## Oneacer (Jan 3, 2011)

You can get a new 212cc Predator for 99.00, so consider that before you start dumping money into it.


----------



## Yard_oppy (Jan 20, 2021)

oneacer said:


> If it was running fine as you say, and started your troubles when you whacked the ice, I would not have touched the carburetor or gas route..
> 
> In my opinion, since I was not there, I would lean towards the jarred key or something ?
> 
> Since you adjusted the valves, you already know about TDC.


I was hoping it was carb/gas related but yeah it's most likely a camshaft bend or gear skipped and broke a few teeth. 
Just wanted some reassuring that I wasn't crazy. Thanks for the prompt and informative response.


----------



## 140278 (Aug 27, 2020)

a fast thing to check is the spark plug, you may find the word bosch on the porcelain in the wrong color and type for a real bosch and f6rtc stamped in the steel, in very small letters if so change it for a real NGK. 
if that doesn't help the cam shaft should be plastic, I only know of two that failed one changed by another member a OPE tech in this site and my own in a 9 hp 265 cc loncin motor


----------



## tpenfield (Feb 24, 2015)

My guess . . . Sounds like the flywheel key may have sheared and the flywheel has slipped on the crankshaft. Now the timing is off. . . .

IMO - that is a 'hazard' / shortcoming of the large single-stage machines. The first thing that the snow sees is a part of the machine moving at high speed (impeller/auger) so when it stops suddenly there is a great possibility of a 'ripple effect' back to the engine.


----------



## 140278 (Aug 27, 2020)

tpenfield said:


> My guess . . . Sounds like the flywheel key may have sheared and the flywheel has slipped on the crankshaft. Now the timing is off. . . .QUOTE]
> 
> Here is what I have done so far:
> Checked spark: perfect
> ...


----------



## Yard_oppy (Jan 20, 2021)

Spark plug is not a fake. Works fine. 
Keyway is intact and working order. 
Flywheel keyway is fine and in working order. 
Spark coil is in good working order. 
Valve adjustment is aligned with TDC. 

I'll be opening it up when I have spare cash to buy parts. 

Thanks for the responses guys. 👍


----------



## groomerz (Feb 7, 2015)

My 2 cents if you have good compression 95 psi means valves are operating. I’m leanining toward ignition 

I’ve seen spark with plug out that is weak that fooled me into thinking good strong spark. Assuming you don’t have a spark tester. Let’s test stir strong spark. Take an old plug bend electrode for a wide gap like my pic. A strong spark will jump this gap











Sent from my iPhone using Tapatalk


----------



## tpenfield (Feb 24, 2015)

captchas said:


> Key Checked . . .


Ooopps , my bad. 😳


----------



## 140278 (Aug 27, 2020)

nah ted! your just reading to fast.

yard oppy
i have seen oem made in china plugs not be able to fire under compression,


----------



## Yard_oppy (Jan 20, 2021)

Changed plug to a known good one. Works fine. 
Still not starting. 
Going into the case now. Have a feeling it's a bent rod/cam. I'll let you guys know what I find.


----------



## vmax29 (Oct 19, 2017)

I had similar issues (flames, popping and fail to run) with an old Yardman and it was a cracked valve. I fixed it with a bead of weld and it lasted for a while. Might be something to look at.


----------



## tdipaul (Jul 11, 2015)

Root causes of shooting flames and popping...


----------



## Yard_oppy (Jan 20, 2021)

vmax29 said:


> I had similar issues (flames, popping and fail to run) with an old Yardman and it was a cracked valve. I fixed it with a bead of weld and it lasted for a while. Might be something to look at.


I have a bent rod. Thanks for the info though!



tdipaul said:


> Root causes of shooting flames and popping...


It's mostly out the carb and less out the exhaust.


----------



## 140278 (Aug 27, 2020)

bent pushrod? have not seen that yet from a loncin


----------

