Craftsman 190cc Push Mower

[peabodyn]

I'm having an issue with an old Craftsman 7.25 190cc mower. It starts easily on the first pull and runs flawlessly, but if i shut it off when it's hot and then try to start it by pulling the rope, it will backfire once and then with repeated pulls it won't start until the motor cools. I don't think the timing is off because it starts easily when cold. After about 15 minutes it will start normally.

I've replaced the spark plug, thinking that it lost continuity when hot, I replaced the thermostat that is controlled by the muffler, I've even took the carburetor off and cleaned it thoroughly all to no avail. If i spray starting fluid into the carburetor during one of the no start times, it will start easily and continue running.

It's an old mower but runs great, so I 'd hate to toss it over this.

Does any have an idea why this mower won't start hot after I've thrown these parts at it?

Thanks

 

[Craftsman Garage]

Sounds like a bad ignition coil. When they get old, they become "heat-sensitive", which is why it doesn't want to start. Or bad gas cap vent/some other fuel system blockage.

 

[Auto Doc's]

Do you have the correct plug the engine calls for... not one that just fits. Parts stores are bad about giving out wrong plugs.

A tired ignition coil is a very good possibility but try cleaning the magnet face on the flywheel to see if the condition improves. Magnets can be strange about rust buildup. The coil air gap can be set with just a simple thin business card squeezed between the magnet and the coil face.

The numbers off of the side of the engine block opposite side from the carburetor would be helpful. If it is much older, the numbers will be stamped into the top starter cover.

B&S had many variations of this engine design.

Depending on the model it may just be a matter of being low on fuel. Some require fuel to be above half a tank for a hot restart.

Last thing I can think of is the valves need adjusting.

 

[peabodyn]

The spark plug installed is a J19LM, I thought about the coil but the engine starts with starting fluid when it won’t start when it’s hot. Still stumped…..

I guess I’ll take it apart again and adjust the air gap on the coil and clean the magnetic parts of the flywheel and check it for a broken key.
I just hate having a simple machine get the best of me.

 

[Oddjob]

Was about to suggest you see if a squirt of carb cleaner would get it to start, then saw your new post. I think you have eliminated the coil or plug as the cause. Does this have an auto-choke? My guess is that once the engine cools the autochoke closes the choke and you can restart but when the engine is hot the autochoke keeps the choke wide open and your engine wants a little choke to start.