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Craftsman snowblower problem

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Re: Craftsman snowblower problem

Postby Josef » Sat Feb 08, 2014 11:11 am

Temp snowblower problem

I have a 2004 Craftsman 27” 8hp snowblower that has seen little use. It began this year running weakly, and tending to surge rhythmically. It made it through the first snowfall, but halfway through the second it quit. It will restart OK, but dies about 15-45 seconds later. Successive restarts die a bit quicker. Going to half choke makes it last slightly longer. I’ve pulled the carb, blown out all the passages, hit them with carb cleaner as well and run a fine wire into all the passages I could get to. Also blew out the fuel line back to the tank. Nothing appeared gunked up at all, but since it seemed likely to be a fuel problem I did all the above anyway. No change whatsoever in the symptoms following the above. I then tried spraying some fuel directly into the carb after starting it (as it began to quit), and that only kept it running a few seconds longer. My conclusion is that it isn’t a fuel problem after all. While I had the carb off I did notice that there was some bluing on the stem for the intake valve (just above where the valve widens out). So now I am thinking that perhaps the intake valve begins to stick as the head heats up (resulting in some burning of the fuel mixture before it enters the cylinder, thereby heating the valve stem). A compression check yielded 55-60 psi while the engine was cold. Your thoughts/suggestions?

OK, thanks all. Lots to cover:

bgsengine – I agree about the coil, but none-the-less I’ll try to rule that out using my timing light.

I kind of ruled out the carb when I couldn’t keep it running by spraying fuel into the carb. In my experience if it is a fuel problem, when you squirt some fuel into the carb as an engine starts to quit it will revive with a burst of power for several seconds for each squirt. In this case it died quickly regardless and to the extent it ran a small amount longer, it was still very weak – no surge of power. Based on that do you still think the carb is the likely cause?

deere2me – I haven’t pulled the valve cover yet to check clearances or look for anything else amiss in there. Do you know what the spec clearances (intake and exhaust) are for this engine?

First thing I did (before even pulling off the carb itself) was to pull the bowl and check/clean the bowl nut/jet. It wasn’t junked up at all, but I cleaned it anyway and that had no effect on the problem. I do have some very fine drill bits, but it really looks completely clean and air blows through it freely.

peanut budda – I wasn’t sure what compression is normal for this engine, so thanks for confirming that it appears to be ok in that respect. I had thought about the tank venting so I tried starting it with the fuel tank cap off but that made no difference. Also, it is hard to imagine it sucking much of a vacuum in the tank in less than a minute.

I used a rubber tip in blowing things out. For most of the orifices I was able to get a pretty good seal and feel air blowing through. I also ran a fine wire into each orifice and found no obstructions (other than bottoming out where a passage makes a turn) and the wire tip didn’t come out with any gunk on it at all for any of the passages.

Again, thanks for the responses. Has anyone seen bluing on a valve stem as I described above, and if so what turned out to be the cause of it?

Joe
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Re: Craftsman snowblower problem

Postby bgsengine » Sat Feb 08, 2014 11:23 am

Josef wrote:
bgsengine – I agree about the coil, but none-the-less I’ll try to rule that out using my timing light.
Unless your timing light is direct connection between the plug wire and plug, that proves nothing - They can still trigger from an induction without a spark actually happening. Inductive timing lights just indicate when there is any sort of voltage movement in the coil wire where the pickup is, it says nothing for whether or not the spark is strong enough to jump a gap (even a gap caused by a coil wire broken internally or an open plug cap resistor)

I kind of ruled out the carb when I couldn’t keep it running by spraying fuel into the carb. In my experience if it is a fuel problem, when you squirt some fuel into the carb as an engine starts to quit it will revive with a burst of power for several seconds for each squirt. In this case it died quickly regardless and to the extent it ran a small amount longer, it was still very weak – no surge of power. Based on that do you still think the carb is the likely cause?
Either the carb or the mounting - gaskets, insulator, etc - all have to be correctly assembled - they can go together several ways, but only ONE right way. Then with these carbs, unless you are intimately familiar with what each hole and orifice and o-ring is for (whether it be air or fuel) they can be ridiculously hard to clean properly. So, generally better to replace carb if you can't get it clean - a Surge is almost ALWAYS from not enough fuel or too much air , rarely the governor itself, and maybe once or twice out of a hundred thousand, a coil issue as KE4 mentioned.

Then there's the intake - if you have any air leaks , bad gaskets, incorrectly assembled gaskets, insulators, cracked intake port (those can break pretty easily if they take an impact the right way, or the studs get cross threaded or overtorqued) any of which will cause an air leak, which in turn means too much air for the fuel the carb can deliver.

So basiclaly, fix the surge first, likely the whole problem gets fixed.


deere2me – I haven’t pulled the valve cover yet to check clearances or look for anything else amiss in there. Do you know what the spec clearances (intake and exhaust) are for this engine?
I do believe it was mentioned prior (or maybe it was another thread) but without the *ENGINE NUMBERS* we can only guess but as a rule of thumb, if no specs at hand, .004" on intake and exhaust is reasonable spec.
Has anyone seen bluing on a valve stem as I described above, and if so what turned out to be the cause of it?

Joe


Blued valve stem on intake usually means it has been running clean and normal - not unusual to see blued valve stems on a low hours clean running engine.
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Re: Craftsman snowblower problem

Postby KE4AVB » Sat Feb 08, 2014 11:58 am

If this blower has the original engine then the engine is either Briggs 12D312-0508-E8 or 12D112-0008-E8 and since it is just before 4/30/2004 it can have either have the LMS or the Ruixing carburetor. The LMS has the right angle fuel adapter that can swivel into different positions and Ruixing doesn't. Only the actual engine numbers and date code will narrow that down further.

As for the valve clearance they are as follows provide above engine numbers are correct.
Intake: 0.004-0.006 in.
Exhaust: 0.009-0.011 in.

On these particular Ruixing carburetors Briggs does have a minor carburetor kit consisting of a float pin, needle valve, welch plug, bowl gasket, and bowl nut gasket. The carburetor insulator gaskets would need to be ordered separately if needed.
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Re: Craftsman snowblower problem

Postby Deere2me » Sat Feb 08, 2014 12:02 pm

Josef wrote:Temp snowblower problem

I have a 2004 Craftsman 27” 8hp snowblower that has seen little use. It began this year running weakly, and tending to surge rhythmically. It made it through the first snowfall, but halfway through the second it quit. It will restart OK, but dies about 15-45 seconds later. Successive restarts die a bit quicker. Going to half choke makes it last slightly longer. I’ve pulled the carb, blown out all the passages, hit them with carb cleaner as well and run a fine wire into all the passages I could get to. Also blew out the fuel line back to the tank. Nothing appeared gunked up at all, but since it seemed likely to be a fuel problem I did all the above anyway. No change whatsoever in the symptoms following the above. I then tried spraying some fuel directly into the carb after starting it (as it began to quit), and that only kept it running a few seconds longer. My conclusion is that it isn’t a fuel problem after all. While I had the carb off I did notice that there was some bluing on the stem for the intake valve (just above where the valve widens out). So now I am thinking that perhaps the intake valve begins to stick as the head heats up (resulting in some burning of the fuel mixture before it enters the cylinder, thereby heating the valve stem). A compression check yielded 55-60 psi while the engine was cold. Your thoughts/suggestions?

OK, thanks all. Lots to cover:

bgsengine – I agree about the coil, but none-the-less I’ll try to rule that out using my timing light.

I kind of ruled out the carb when I couldn’t keep it running by spraying fuel into the carb. In my experience if it is a fuel problem, when you squirt some fuel into the carb as an engine starts to quit it will revive with a burst of power for several seconds for each squirt. In this case it died quickly regardless and to the extent it ran a small amount longer, it was still very weak – no surge of power. Based on that do you still think the carb is the likely cause?

deere2me – I haven’t pulled the valve cover yet to check clearances or look for anything else amiss in there. Do you know what the spec clearances (intake and exhaust) are for this engine?


First thing I did (before even pulling off the carb itself) was to pull the bowl and check/clean the bowl nut/jet. It wasn’t junked up at all, but I cleaned it anyway and that had no effect on the problem. I do have some very fine drill bits, but it really looks completely clean and air blows through it freely.

peanut budda – I wasn’t sure what compression is normal for this engine, so thanks for confirming that it appears to be ok in that respect. I had thought about the tank venting so I tried starting it with the fuel tank cap off but that made no difference. Also, it is hard to imagine it sucking much of a vacuum in the tank in less than a minute.

I used a rubber tip in blowing things out. For most of the orifices I was able to get a pretty good seal and feel air blowing through. I also ran a fine wire into each orifice and found no obstructions (other than bottoming out where a passage makes a turn) and the wire tip didn’t come out with any gunk on it at all for any of the passages.

Again, thanks for the responses. Has anyone seen bluing on a valve stem as I described above, and if so what turned out to be the cause of it?

Joe


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Re: Craftsman snowblower problem

Postby Josef » Sat Feb 08, 2014 1:29 pm

OK, thanks again:

Bgsengine – My timing light is the old style (where you put the spring extender on the spark plug and attach a lead to that), so I think it takes a decent spark to trigger it. Nothing on the engine had previously been apart and it ran ok until this year, so I think incorrect assembly (even by the manufacturer) can be ruled out. It is also not the governor – I held it in a fixed position (partial throttle) and the engine quit anyway. Also no chance of anything impacting the carb assembly – it’s all under a plastic cover. I wasn’t aware that bluing of the valve stem is normal. That pretty well kicks my speculation that it might be due to the value sticking (closing slowly) as the head heated up.

What do you make of it that squirting fuel directly into the carb doesn’t give a few seconds of run time? That’s worked for me on everything from model airplane engines to car engines when it comes to diagnosing fuel/carb issues.

The only engine numbers I could find (without taking covers back off) is on a decal on the fuel tank. It reads: “Family: 5BSXS.2051HF 27603” and indicates that the Air Index is 2. Per the owner’s manual, the engine model number is 12E114-0268-E1. Per the manual, the carb part number is 790558, but it doesn’t give a manufacturer for the carb and again I’ll need to take the covers back off to see what may be stamped on it.

Deere2me – Sorry, I missed seeing the valve clearance numbers you gave when I was going through the replies.

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Re: Craftsman snowblower problem

Postby bgsengine » Sat Feb 08, 2014 2:28 pm

Josef wrote:
What do you make of it that squirting fuel directly into the carb doesn’t give a few seconds of run time? That’s worked for me on everything from model airplane engines to car engines when it comes to diagnosing fuel/carb issues.
Might fire but not run - depends on the fuel and amount of fuel. and again an air leak or a valve clearance issue can also cause you problems. Raw fuel does not necessarily mean anything (It will NOT burn - You can actually put out a fire by dumping gas on it though that is NOT ever recommended!- Liquid gas does not burn - It is the VAPORS above the gas that burns) - It has to be ATOMIZED (by the carburetor) and VAPORIZED (heat and compression) to achieve the most bang for the buck. - Pouring raw fuel down the plug hole works because the piston movement and air pressure will partially atomize and vaporize the fuel.. Squirting gas in the carb throat *sometimes* works if you are able to atomize (mist) the fuel, or it sits long enough for sufficient fuel vapor to mix with the air. So it depends a lot on how the fuel is being introduced to the carb (and fuel is less volatile, less likely to vaporize in cold weather) - As well, if there is any water present in the carburetor (mixed in the gas somehow, or ice, etc.) there'd also be a problem.

The only engine numbers I could find (without taking covers back off) is on a decal on the fuel tank. It reads: “Family: 5BSXS.2051HF 27603” and indicates that the Air Index is 2. Per the owner’s manual, the engine model number is 12E114-0268-E1.
Engine numbers are stamped in the valve cover - hard to see or read them on those engines unless you know *exactly* where they are, and are able to get the right line of sight over the air cleaner box and past the breather tube.
Per the manual, the carb part number is 790558, but it doesn’t give a manufacturer for the carb
Manufacturer is Briggs & Stratton. That is an OLD part number (if it is indeed the correct one, You need the Date Code off the engine, as well.) Part number supercession data:
790558 ->791292->791953->794587->798917 (About $65 - $70, and may be subject to change as I didn't check current distributor data)
and again I’ll need to take the covers back off to see what may be stamped on it. - Which is the point I was making about MTD carbs - They had lots of problems, and judging by the multiple part number changes, meaning updated carburetor, Briggs may have seen the same issue with them as well. (Or, they changed suppliers multiple times)

Joe

Sight over the air cleaner and past the breather tube and look at side of valve cover, you should see all or part of the engine numbers stamped in valve cover.
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Re: Craftsman snowblower problem

Postby frankp » Sat Feb 08, 2014 11:28 pm

Is this an OHV Brigs? I had two craftman snowblower, about same age, in for repair this week. One had a bent push rod, and the nut came off the rocker arm on the other. How bad is this?
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Re: Craftsman snowblower problem

Postby Josef » Sun Feb 09, 2014 2:01 pm

Bgsengine – I found numbers stamped on a plate on the side of the engine (not on the valve cover, but near it): 12E114 0268 E1 and 040909 FE. The former matches model number in the owner’s manual and I assume the latter is a date code or serial number. There were 3 separate sets of numbers I could see on the carb (B102, 0417, and 2324) along with a tiny B&S logo. The fuel inlet is the plastic type, not the bent metal tube.

I’m aware of the need for the mixture ratio (vapor, not liquid) to be within a flammable range although I’m not sure you could ever succeed in dowsing a flame by pouring gas on it – enough air would almost certainly be entrained to have some part of the mess within the combustible range (which is pretty broad for gasoline). However you certainly can throw a match in a gas can or fuel tank and just have it snuff out. (Don’t try this at home kiddies!)

Squirting some fuel into a carb to keep an engine running for a few seconds (and even a minute or more, if you keep squirting in a little more each time it fades) has been how I’ve always confirmed that everything else in an engine (spark, compression, timing, etc.) are good enough for the engine to run. By elimination, that means I’ve got a fuel/carb problem. Since that wouldn’t keep this engine going, it seemed to indicate some other problem. However, it looks like a replacement carb runs about $60, so I’ll likely try that if I don’t see anything amiss when I pull the valve cover off (hopefully later today).

As for the fuel, it did start this year with old fuel in it (and it made it through the first snow with some new fuel just added to the old). When I worked on the carb I drained the tank completely and used fresh fuel, but that didn’t change anything. And it’s garage kept so there’s little chance of any water or ice in there now.

frankp – I’m not sure what you mean by “How bad is this?” As described above, it starts and runs for a short time, and it isn’t making any particularly nasty engine noises while it is running. It is an OHV Brigs model.

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Re: Craftsman snowblower problem

Postby bgsengine » Sun Feb 09, 2014 2:58 pm

Josef wrote:Bgsengine – I found numbers stamped on a plate on the side of the engine (not on the valve cover, but near it): 12E114 0268 E1 and 040909 FE. The former matches model number in the owner’s manual and I assume the latter is a date code or serial number.
Yup, Tells us it was built September 9 , 2004

As described above, it starts and runs for a short time, and it isn’t making any particularly nasty engine noises while it is running. It is an OHV Brigs model.

Joe

If it starts and runs a short time when squiring gas into the carb, that does indicate that you have a fuel problem. It is possible you are squirting TOO MUCH gas into it (which floods the engine out) - Might have best luck with a spray bottle such as used for window cleaner. Some engines are very sensitive to over-fueling and easily stall out if given just a bit too much gas - once it is running your air flow is stronger and it may be sucking in TOO much gas and stalling out.
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Re: Craftsman snowblower problem

Postby Josef » Sun Feb 09, 2014 3:38 pm

Bgsengine – Let me try to be clearer about squirting fuel in. In this case since it starts and runs for a while (without needing to squirt fuel in first), again typically running about 15-45 seconds, as it begins to die I’ve tried squirting some fuel directly into the carb to try to keep it running. That has had minimal effect – it might stagger on for a couple of seconds longer than it otherwise would have, but there is no surge of power for a few seconds as I would have expected if it were fuel starved. Since it will restart right after that and run for another 15 or whatever seconds, I don’t think it is flooded either. You are certainly right that you can put in too much or too little fuel, but I’ve done this many times on many engines so I have somewhat of a feel for it and in this case it’s just not having much effect.

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