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Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

"Sometimes pull cord kicks back" Sounds like your flywheel sheared the key.

upupandaway said:

"Sometimes pull cord kicks back" Sounds like your flywheel sheared the key.

Click to expand...

No the key is perfect.
Thanks though.

Pop ,
You have been looking at too many bad You Tube videos
A bit of background would be helpful
Owned since new ?
fond on the curb ?
Bought "reconditioned "

I for one would start with a new fresh spark plug because they are cheap
The important resistance on a spark plug is the one the air gap makes at cylinder pressure.
Modern fuel vapour is conductive at cylinder pressure so if the engine does not fire a few times then the centre electrode gets damp and the sparks tack down the side of the insulator, rather than jumping the spark gap .

PopIggy said:

Checked flywheel shear pin and looks great.

Click to expand...

You need to pull the key out and look at it all over. Retorque the flywheel nut to factory specs. Several times we get the same report, key looks good. Later on they remove the key and find it's messed up.

PopIggy said:

sometimes there is a small back fire through the carb.

Click to expand...

Ignition timing issue. Check the FW key.

bertsmobile1 said:

Pop ,
You have been looking at too many bad You Tube videos
A bit of background would be helpful
Owned since new ?
fond on the curb ?
Bought "reconditioned "

I for one would start with a new fresh spark plug because they are cheap
The important resistance on a spark plug is the one the air gap makes at cylinder pressure.
Modern fuel vapour is conductive at cylinder pressure so if the engine does not fire a few times then the centre electrode gets damp and the sparks tack down the side of the insulator, rather than jumping the spark gap .

Click to expand...

bertsmobile1 said:

Pop ,
You have been looking at too many bad You Tube videos
A bit of background would be helpful
Owned since new ?
fond on the curb ?
Bought "reconditioned "

I for one would start with a new fresh spark plug because they are cheap
The important resistance on a spark plug is the one the air gap makes at cylinder pressure.
Modern fuel vapour is conductive at cylinder pressure so if the engine does not fire a few times then the centre electrode gets damp and the sparks tack down the side of the insulator, rather than jumping the spark gap .

Click to expand...

Believe the year is 2011
Neighboor owed it since new.

I will put now plug in tomorrow. Then I will pull flywheel and inspect shear pin key.
Many Thanks to everyone.

Being 10+ years old I’m thinking you have a fuel issue. When you cleaned the carb, did you check the float level? I’m thinking the float needle seat may have swollen, causing a severely lean condition.

Rivets said:

Being 10+ years old I’m thinking you have a fuel issue. When you cleaned the carb, did you check the float level? I’m thinking the float needle seat may have swollen, causing a severely lean condition.

Click to expand...

Float and needle are preforming as they should.

But is the float level? If you turn the carb upside down, the float shout be level or slightly lower on the side opposite the float pin.

Replace plug. Gapped at .03. still won't start.

you say cleaned carb. Did you replace all the gaskets with new OEM ones? You might also want to search here for threads on the primer built into the air cleaner base. I think some people have had issues with those. I'd put a half teaspoon of gas or a squirt in the carb throat with the air cleaner out, and see it it fires right up for a few seconds. That will tell you if you have a fuel supply problem.

New plug and gaped to .03 and still doesn't start.

sgkent said:

you say cleaned carb. Did you replace all the gaskets with new OEM ones? You might also want to search here for threads on the primer built into the air cleaner base. I think some people have had issues with those. I'd put a half teaspoon of gas or a squirt in the carb throat with the air cleaner out, and see it it fires right up for a few seconds. That will tell you if you have a fuel supply problem.

Click to expand...

Yes all new gaskets. Unit dose not have primer bulb, it is an automatic choke. Also getting beautiful blue spark from plug.
Will not attempt to start even after priming carb.

PopIggy said:

Float and needle are preforming as they should.

Click to expand...

How do you know? What testing was done to rule them out?

PopIggy said:

Yes all new gaskets.

Click to expand...

Did you over torque them now causing vacuum leaks? No impact guns required here. Use your off hand to limit torque.

the manual I looked up for that sears model showed a primer bulb style air cleaner.

sgkent said:

the manual I looked up for that sears model showed a primer bulb style air cleaner.

Click to expand...

Primer bulb is only 4 cycle engine.

PopIggy said:

Primer bulb is only 4 cycle engine.

Click to expand...

I might call BS or should I assume you might be a data collector / future spammer trying to build a thread count? The manuals that are online only show a 4-cycle Briggs and Stratton engine for "917.370430." You might want to list the engine type and show some photos if it has been changed to a 2-cycle engine. The Sear's OWNER'S manual only lists Engine, Briggs and Stratton, Model Number 126M02-1525-F1 of which the air cleaner base is illustration part 966, 795259 "Base-Air Cleaner Primer."

PopIggy said:

Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

Click to expand...

You need to remove the Flywheel to properly check the key. Perhaps you just looked at it.

If your Flywheel Key is in perfect condition try a new spark plug.

Sometimes you can get kick back if there is no blade on it.

PopIggy said:

Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

Click to expand...

Evil spirits...

Bad valve adjustment ??

if it snaps back hard on you then the flywheel key could be it or the exhaust valve is not set correctly and or the compression release is not working.

Try some Quick Start spray. Hold Handle tightly. If it fires, it is not a Fuel or Ignition Problem

PopIggy said:

Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

Click to expand...

Hi, have had similar issue to this , where the valve seat had migrated out of position and was not sealing on the valve, would backfire out of the carby, also a stuck valve will give similar symptoms.
if you spray some brake cleaner in carby and it starts for a bit then you may have fuel supply issue, otherwise check inlet and exhaust valves are operating ok, and if you can do a compression test that will confirm it….good luck.

PopIggy said:

Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

Click to expand...

Based on your info, sounds like the timing is off so if the flywheel key isn't sheared as per your report, could be a broken camshaft. The Camshaft shouldn't break unless you hit something and the camshaft gave instead of the shear pin. I would make sure the valves are properly opening and closing as you next troubleshooting step.

clfrank13 said:

Based on your info, sounds like the timing is off so if the flywheel key isn't sheared as per your report, could be a broken camshaft. The Camshaft shouldn't break unless you hit something and the camshaft adequate. instead of the shear pin. I would make sure the valves are properly opening and closing as you next troubleshooting step.

Click to expand...

It does sound like the timing is off which would mean a sheered key. However I would definitely leak down test and see if the valves are leaking and if compression is adequate. Also check for air intake leaks.

OK, lets make all this very simple.

Fuel to carb
Spark to cylinder
Compression
Timing / Governor
Have all ---> MUST START.

So, spray in some starter fluid, if it starts, then you immediately rule out a TON of possible issues that waste time chasing down dead ends.
Starter fluid, still wont start at all?

ELECTRICAL: Check the spark - $6 tool. Spark? yes? NO - try new plug, spark? yes/No? Check the magneto, the gap, the resistance. Check to see if there is a ground either the magneto or from the key - this could be something as simple as a key off/on ground. Also safety interlocks ( seat/brake/ mower - "kill - short to ground."

COMPRESSION compression test, leak down test

Be a diagnostician not a parts changer that defines about 90 % of all the "experts"


EM

PopIggy said:

Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

Click to expand...

Check the coil gap to flywheel and take some Emory clock and clean the facing on the flywheel. Try a new coil or check to see the resistance is within limits. Did you pull the float bowl and make sure it is full of gas and check the needle and seat for proper operation and float level is correct?

EdBread said:

OK, lets make all this very simple.

Fuel to carb
Spark to cylinder
Compression
Timing / Governor
Have all ---> MUST START.

So, spray in some starter fluid, if it starts, then you immediately rule out a TON of possible issues that waste time chasing down dead ends.
Starter fluid, still wont start at all?

ELECTRICAL: Check the spark - $6 tool. Spark? yes? NO - try new plug, spark? yes/No? Check the magneto, the gap, the resistance. Check to see if there is a ground either the magneto or from the key - this could be something as simple as a key off/on ground. Also safety interlocks ( seat/brake/ mower - "kill - short to ground."

COMPRESSION compression test, leak down test

Be a diagnostician not a parts changer that defines about 90 % of all the "experts"


EM

Click to expand...

One other thing to check. IF you have an electrical fuel shutoff Solenoid (JD and Others) make sure you can hear/feel it click when you turn the key to ON. If you cannot, there is a rectangular 10 wire connector a few inches from the Ignition switch. Pry down lock and pull apart. Clean all terminals as best you can and spray with Zep Battery Care foam. RE and Disassemble a few times to enhance cleaning. If you cannot feel that solenoid click by holding it with your fingers as you turn key to ON, it is NOT Opening to allow fuel through the carb. By shutting off the fuel flow, this is how the engine is stopped when key is turned off. Then follow ED advice.

PopIggy said:

Hi all,
I am working on this mower and she won't start.
Cleaned carb with brushes and wire it is definitely getting fuel.
New air filter. Drained fuel tank and using new fuel.
Plug measures 15000 ohms which is good and light tester
lights when cord pulled. Sometimes pull cord kicks back and
sometimes there is a small back fire through the carb.
Checked flywheel shear pin and looks great.
Any other ideas?
Many Thanks in Advance.
PopIggy

Click to expand...

Did you get this fixed? If not -email me riceski@gmail.com