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Carb probelms-won't start.


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11-15-05, 01:36 PM   #1  
Carb problems-won't start. 8hp Craftsman Snowblower

I have an 8hp Craftsman snowblower. I put all new carb parts in it using the engine and model #.
Now, it either back fires or starts and runs for 10 seconds. It also backfires out the back of the carb as well. Gas doesn't pour out the back of the carb and it seems to be getting enough fuel. I 've started with the main and pilot jets turned out 1/2 turn from closed and gone from there but nothing seems to make a difference? The carb has a float.
Could this be a govenor problem?

Help!


Last edited by Square Head; 01-10-07 at 05:07 PM. Reason: Spelling
 
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11-15-05, 02:31 PM   #2  
It is highly unlikely that you have a governor problem. You didn't provide any engine ID numbers but generally the needles are as follows: High - 1 1/2 to 1 3/4 out from seated; Low - 3/4 to 1 1/4 turn out from seated. The popping may indicate an ignition problem. Again, if we had the engine ID numbers, we'd be better able to advise you if in fact you have an ignition issue, whether it would be points & condensor issues, coil issues or flywheel key issues as the likely root cause. Post back with engine make, model, serial/spec. and code/DOM.

 
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11-15-05, 07:19 PM   #3  
The #'s

Hi, Here are those #'s.

Carb-631924.
Engine- 143-666322
Ser#- 6243D
Model- C944-526500

I put new point and condenser in a couple seasons ago.
Set the gap to .013"
Spark plug is new and set at .030"

 
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11-22-05, 02:56 AM   #4  
Did you install genuine Tecumseh points & condensor or aftermarket? Furthermore, the proper gap is .020". Yours being set at .013" could certainly cause it to fire back through the intake. When you did replace them, did you happen to also move the stator plate thereby throwing off the ignition timing? Hopefully not but if so you'll want to set the timing properly for which you'll need a multi-meter and a dial gauge indicator. If not, and even though the points & condensor are relatively new, I'd replace them again with Tecumseh parts, part numbers 30547A, points and 30548B, condensor.

 
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11-22-05, 02:45 PM   #5  
Puey.

Thanks, I'll give this a shot this weekend and let you know the outcome.

Can't remember about the type of parts, I'll be sure to check!

Mike.

 
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09-10-06, 01:09 PM   #6  
I'm Back.

Never did get it running. I gapped the points to .20".
Now I have no spark. Can you get a CDI ign. box for this model?
How much are they?
Started playing with it today before the snow flies.

 
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09-14-06, 03:10 AM   #7  
You cannot get a solid state ignition for this engine as it has the ignition components under the flywheel. Again, did you install genuine Tecumseh points and condensor? Did you mistakenly loosen and move the plate that the points are housed in? The poping out the carburetor indicates either an improperly timed stator, a sheared flywheel key or an intake valve issue. If you loosened the stator plate and moved it, the ignition timing will be off. If the key is sheared the ignition fires sooner - before the intake valve can close. If the intake valve or valve seat is burnt, pitted or has insufficient clearance, it will not seal as it should and allow combustion gasses to pass by and into the carburetor. By the way, the correct carburetor kit you should have used is part number 631782 and the carb to manifold gasket is 33263 and the manifold to block gasket is 27915A. When you did service the carb, did you soak it in a good bath type cleaner? I like Napa # 6402.

 
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09-14-06, 05:29 PM   #8  
Gap

The carb was totally cleaned out. Non chlorinated
Yes, I used Tecumseh points and condenser.
The fly wheel is good and clean inside and no shearing of the key way.
I think the stator plate is moved? I gapped the points at the highest spot on the crank (open) at .20". I have no spark at all now. Didn't loosen the plate when doing the install.
How do you gap the points?

 
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09-15-06, 03:03 AM   #9  
Has the stator plate moved??? Again, if so, your ignition timing is now off. It sounds as though the points are set properly....020" at full open. Full open is when the flywheel keyway of the crankshaft is in a position where it is straight up towards the top of the piston. If the stator has moved you will need a dial indicator, a multi-tester (with ohms or continuity readings) and a new head gasket. If you suspect the stator has moved post back. The only way it would have moved is if you physically moved it yourself by way of loosening the two screws that hold it in place.

 
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09-15-06, 06:11 PM   #10  
Good News.

I didn't move the stator plate. It's timed wrong. I wasn't watching for the keyway to be sitting at 12 o'clock.
I shall re-do it this weekend.

 
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12-02-06, 09:45 AM   #11  
Snow.

Great, we have snow now and I still haven't done anything with the snow blower.
The stator plate has not moved, that I know.
So the crank keyway needs to be at 12 o'clock then gap the points?
.20" is correct setting.
I shall try again tonight in the garage.
Wish me luck!

 
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01-08-07, 07:38 PM   #12  
Timing.

Well, I did the timing on Sunday night and had sucess.
There is lots of spark now!! But it still won't start??
I bought a Tech book by Haynes. I'm going through the carb again.
I might have missed something??
It's getting gas. Not flooding but the plug is wet after turning it over
for awhile.
Adjusted the carb screws as per the book as well. I wasn't far out at all.

What do you think?

Mike.

 
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01-08-07, 10:43 PM   #13  
Does the engine have compression?


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01-09-07, 11:47 AM   #14  
Compression

That's my next idea. Is the head gasket blown?
Not sure, but I will test it.

 
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01-09-07, 03:21 PM   #15  
The point gap should be set at .020" not .20"..
Big difference..

 
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01-09-07, 07:22 PM   #16  
Correct, but I'm pretty sure he meant .020" because if he set them at .20" he wouldn't have any spark at all.


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01-10-07, 05:02 PM   #17  
Gap.

Oops.
No, I meant .020"!!!
Yes there is lots of spark.

 
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01-11-07, 04:22 PM   #18  
How old is that engine?

Sounds like you have lots of spark and lots of gas; only thing left is the intake valve which could be sticking on an older engine that spends more time sitting than working. You could take the head off, (with a new head gasket on hand), and watch the valves work as you turn the crank. I've found even the tiniest little bit of carbon under the valve head can prevent it from closing fully, and causing a backfire out the carb. You might be looking at lapping the valve(s) to get them seating properly again.

 
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01-11-07, 06:47 PM   #19  
Valves.

I lapped the valves last spring. They are opening/closing as well.
The clearance is good.
I bought a new head gasket today for $8.20
Worth a shot. I didn't replace it last when the valves were done.
I have a good feeling!!

 
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01-16-07, 09:56 AM   #20  
So is it running now? Just curious. If the valves are OK and a new head gasket is in place, either it has to run or back to square one. Never seen an engine I couldn't start. Just that a few of them weren't worth the trouble.

 
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01-26-07, 04:46 AM   #21  
Please -- I have been following this thread -- did you get it running and if so what did you do.

 
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02-04-07, 07:21 AM   #22  
Sorry guys, I haven't had a chance to look at it!!!
I will post back when I do.

 
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10-14-07, 08:41 AM   #23  
Snow Blower.

Well, it's still not running!!
I replaced the head gasket as well.
Now I have no Spark.
I took the points and condenser out last night. Cleaned everything completely. Re-installed, and placed gap at .020".
The points have no wear at all. The condenser is quite new as well. Cleaned all the grounding connections.
The motor is a HM80. Techcumsee 8 HP / Craftsman.
One manual I have calls for a RJC8 Spark plug.
The other claims RJ19LM??


Need help guys. Running out of options.
My wife just laughs at me!!
"You will never get it running"
Have to prove her wrong now.

 
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10-15-07, 02:19 AM   #24  
I'd say it is time to replace the ignition coil, Tecumseh part number 30560A. How is the condition of the flywheel key? Absolutely sure it is not sheared?

 
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10-15-07, 06:26 AM   #25  
The fly wheel key is fine-not sheared off.
This unit has breaker point ignition. No coil.
I've been told its too old to change it over to CDI???

 
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10-15-07, 08:05 AM   #26  
Now I see what you mean.
I'm thinking CDI-wrong.
I will look closely at the manual to test the coil for Ohms
as well.
All else seems good. No spark at all.
Spark Plug RCJ8??

 
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10-18-07, 06:42 PM   #27  
Stator???

If the coil is removed, does that mess up the stator position?
Coil coming in tomorrow. $42-expensive to say the least.
Can I mark the position on the old one or do I need a dial indicator?

 
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10-19-07, 11:57 AM   #28  
My list price for a Tecumseh 30560A, ignition coil is $28.06...fair as far as I'm concerned. No, you don't need to re-time the stator as long as you didn't loosen the two stator bolts to remove the coil. And, you don't need to, by the way. Did you loosen the two bolts?

 
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10-20-07, 11:07 AM   #29  
Hmmm.

I replaced the coil without moving the stator bolts.
Still no spark????
The condensor / points have barely any hours on them. Gapped to .020" with key way at Top center on shaft. Everything is clean ground connections, points, wiper, ignition housing.
How can one measure the Fly Wheel clearance vs. the coil contacts??? Should be at .0125"

Any thoughts???

 
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10-20-07, 09:43 PM   #30  
Sucess!!

Yes the spark is there!!
The machine runs as well.
I guess persistence pays off.
thanks for everyone's input.

 
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10-21-07, 05:58 PM   #31  
By the way, there is no adjustment for internal Tecumseh ignition systems, they're factory set.

 
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