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Hi everyone, I am a first time poster. My son purchased a craftsman lawnmower 247.377300 and it has a 5X65RU motor. He bought it at a private sears hardware store that closed out and lost the receipt. The regular local sears store will not honor the warranty unless he produces the receipt.

The problem with mower is that its a non choke and supposed to start on first pull. After 10 or more pulls, it fires up cold and will run. When he shuts the motor down to empty the bag, it will not fire up. I sprayed some carb cleaner in it and it still will not fire up. I am a mechanic, but not good with small engine repair. I have a spark plug tester and the spark looks good. Any suggestions? Does the problem appear to be fuel or something electronical? Any help or guidance would be appreciated..

Thanks
bizzs

https://www.briggsandstratton.com/n...nemanuals.html?searchrequested=126t02-0521-b1

see page 9 in operators manual & adjust valves, intake 0.005- 0.007 exhaust 0.007-0.009

https://www.google.com/search?sourc...ves on b&s engine&aqs=chrome..69i57.31365j0j8

I would start with trying a new plug. Depending on type of spark tester can give false positives. If that doesn't work, then go changing the fuel, and then to cleaning the carb, If that doesn't get it try varying the gap on the ignition module. Possibly could also be partially sheared flywheel key, so may want to check that.

I have run into all the situations I have listed on the MTD branded engines at one time or the other, all with the same symptoms that you are listing.

thanks guys I will use your words of wisdom and get back to you with my findings.

Ok guys here is what I did and the motor is still doing the same thing. I disassembled the carb and cleaned, cleaned the gas tank and replaced filter. Replaced spark plug and adjusted coil. The ground wire is in tact and is working properly. The motor fired up and ran good and I shut it down after a minute run. It would not restart again. I sprayed some starting fluid in the carb and still no start. I can see spark through my tester. I left the air filter off and one observation that I seen was a slight spit backfire coming from the carb when it was running.

My son told me last night that this mower was a customer return to the private sears hardware store that went under and it was resold to him at the closeout sale. My son became the proud owner for 80.00 and was informed that the warranty was good so he decided to buy it (lol)

Any recommendations for my next step? Is it possible that the coil is bad since it will not start using starting fluid?

thanks
bizzs

May need to do a compression test after you run it and then shut if off and it won't restart. Compression is suppose to be 55-85 psi.

ILENGINE said:

May need to do a compression test after you run it and then shut if off and it won't restart. Compression is suppose to be 55-85 psi.

Click to expand...

I did the compression test and the results were 100 psi when the engine was cold. I started the motor and let it run for 10 minutes and shut it down. I tried restarting with negative results. I took another compression reading with the motor hot and the result were 102 psi.

Comments please?

Thanks
bizzs

You have a carbon canister under engine cover find it and check to see if it is clogged.

Canister is clean. I adjusted the valves to 0.006. It starts up but is chugging like it is starving for fuel. All of a sudden it kicks in and the idle goes high and then it smooths itself out and runs great. When I shut it off, it will not start again. The plug is clean and not fouled out. I try starting fluid and still no start after I shut it down. Any thoughts? Coil?

thanks
bizzs

I made a youtube video. https://youtu.be/wgFCJG_6Mgc

Any thoughts?

You mentioned in your first post that it was a non choke engine, but it acts just like a choke that is not opening. You may have mentioned it or I missed it, but did you check the flywheel key. partially sheared keys will cause the same thing.

Thanks for the reply. The choke is automatic and it is temperature controlled by the heat from the exhaust. I did not check the key because I was thinking that it was too new to sheer. I will pull the flywheel off and check it out. Any other ideas? Could this be electrical since it will not start back up after I shut it down, even with starting fluid?

Thanks
bizzs

I pulled off the flywheel and they key was intact. I removed the key and inspected it finding no cracks or sheared parts. Thoughts?

bizzs

In your first post you said it was a non choke, which I was thinking primer. But you said that the choke is thermo controlled by the heat of the muffler, which make it an automatic choke. If I understand correctly. run the engine from cold for a few minutes, and shut off the engine, and remove the air cleaner and make sure the choke is staying open.

If the choke isn't opening slightly after startup and then continue to open it will run just like the youtube video.

The choke does open. I removed the air filter cover from the carb and I have full view of the butterfly. When its cold, it is shut closed. When the motor starts, I observe the butterfly open slowly about a quarter of the way. If I open the butterfly all the way manually, the engine stalls. Take notice on the video on how the mower runs for almost a minute and then the idle rpms increase and then it smooth out. At this point the choke is wide open. When I shut the motor down, it will not start up again until the motor is cool, even if I spray starting fluid inside the carb. Thoughts?

Thanks
bizzs

Where did you get the valve clearance sizes? Normally they are a range and different for exhaust and intake. You normally set them 1/4 turn past TDC with both valves closed.

I changed the settings since that post. I downloaded a service manual from MDT for a motor that looked like mine. I set the intake to 4 and exhaust to 7. The range was 3 to 5 and 6 to 9. I set them at TDC with a feeler gauge

bizzs said:

The choke does open. I removed the air filter cover from the carb and I have full view of the butterfly. When its cold, it is shut closed. When the motor starts, I observe the butterfly open slowly about a quarter of the way. If I open the butterfly all the way manually, the engine stalls. Take notice on the video on how the mower runs for almost a minute and then the idle rpms increase and then it smooth out. At this point the choke is wide open. When I shut the motor down, it will not start up again until the motor is cool, even if I spray starting fluid inside the carb. Thoughts?

Thanks
bizzs

Click to expand...

My thought is you have a partial flooding situation not a lean run problem. And if it is flooding, spraying starting fluid may just increase the flooding problem.

Thanks for the reply. I am at it again the morning.. Please bear with me for being such a pest. Any guidance you can offer to diagnose a partial flooding problem is appreciated? I have just about every mechanical tool to fix cars and I am determined to find the solution. I am puzzled! I can usually fix mechanical things easily, but this is new and has me obsessed to get her running again.

thanks
bizzs

Well I gave it my best shot today and no luck. I have no clue what is causing this problem. I spoke with the manufacture today and was told that the compression should be between 55 and 85. Mine is over 100. What could be the cause of this? I suspect the high compression or an ignition coil may the culprit to this. Anyone have any thoughts on this?

The tech manual says reading over 85 is possibly due to a non working compression release. Maybe that could be coupled to a ignition system that can't produce enough energy at low rpm's to overcome that compression and therefore isn't actually firing the plug.