Craftsman lt100 19.5 Briggs

[metalslayer]

Hi all noob here----end of last yr front axle cracked--finished the yr w/ a borrowed push mower(not easy w/ 1 acre--lol). Fixed front end and motor won't run right.Full power after cold start--then I have to keep increasing choke as time goes by--till the motor will be severely underpowered---was better after choke cleaner(carb still attached)---replaced plugs---oil looks a lil thin----thanx in advance---Bill

 

[Rivets]

Sounds like you have a fuel delivery problem. Check for parcialy plugged fuel lines, fuel filter, tank or gas cap. The first thing I would check is the gas cap. When the problem occurs loosen the cap. If the vent is plugged it will not allow fuel to flow, but creat a vacuum in the tank.

 

[metalslayer]

Had already replaced fuel filter and tried the gas cap thing----going to look into it some more in the am---saw somewhere that something in the carb might be sticking open---but mine is 12 years old and I don't see where any wires are attached to the carb.

 

[GentlemanFahmah]

Sounds like a gummed up carburetor is restricting, then flooding fuel delivery.

New fuel formulas (E85, etc) are horrid and wreak havoc on small and vintage engines. Likely have shellac in carburetor bowl which is plugging and sticking needle, seat, and float. Get a can of carb cleaner and remove and disassemble carburetor and clean the needle and seat thoroughly.

If that's above your comfort level, you can try to squirt some carb cleaner down the throat of the carburetor but it likely will not reach the area where the problem is. Injector cleaner also might help clear it if it's running and you can get the injector cleaner through the system, but really you need to clean the carburetor. Just be patient taking it apart watching for little parts like the pin and spring on the float and watch how the needle attaches to the float carefully for proper reassembly. Not rocket science, but requires a clean workspace with good lighting.

 

[wildbill]

I have had same cases in my shop. It is very likely the carb problem. I also have a craftsman LT1000, 12 years old I believe. If you do not want to tackle the carb removal, there is a trick you can do:

1- Use a clamp or small flat nose vice grip pliers to stop gas from going into the carb bowl.
2- Start the mower and use all the gas in the carb bowl.
3- Go get a spray can of carb/choke cleaner
4- Pull the gas line off the carb where it enters the bowl.
5- Fill the bowl with the cleaner, make sure it is FULL
6- Let is sit in there for about 20 minutes.
7- Hook the line back up to the carb
8- Remove the gas line blocks, fire it up.

If this does not do the trick the first time, repeat the steps again.

Also, there is an anti-backfire solenoid that screws into the bottom of the carb and has a wire attached to it. Have some sit on the seat and push the brake pedal as if ready to start it. Take an 8" or so screwdriver and put the tip against the bowl, put the handle against your ear as if a stethoscope. Have someone turn the key on-off several times. You should hear a 'click' when the key is turned on-off. If not, it is likely the solenoid is either gummed up and not opening enough to allow gas to flow through the main jet or not working well. It takes a 1/2" wrench that has been ground thin enough to reach the 'flats' between the carb bowl and the solenoid, Just unscrew it, then take a pair of cutters and cut the plunger off. Screw the unit back in. Besides, the solenoid is pretty much useless, and IF the mower does backfire, so what..... it means you have just turned off the mower and a little 'pop' of the backfire is in celebration of your just finishing mowing the yard!