I have a Sears Lawn Tractor model numberNNN-NN-NNNNwith a Briggs & Stratton Engine Model 445677 Type 1188-B1. The engine has 90 hours operating time. After the engine runs for 20 to 30 minutes, the engine speed surges up and down and will cut off. At that point, the engine will not start until it cools down. I recently replaced the fuel filter, air filter and spark plugs. Your thoughts are greatly appreciated. Bob
Nothing but am thinking of putting some seaform in the gas to try to clean the carburator
Hello Bob and Welcome to Just Answer,
Since your unit will run for nearly 3 minutes before the problem starts then we will need to do a quick check to get us headed in the right direction. I need for you to run the unit until it stops. Once it quits you will want to remove the air filter and put a little bit of gas into the hole under the air filter. If it starts up then you likely have a fuel problem. I would replace the fuel cap, replace the fule lines, and rebuild the carburetor. If it does not attempt to start then the problem is likely a spark problem such as a bad ignition module. Check the fuel test first and then let me know.
J R - This morning the engine would not start at all. I removed the air filter and injected 5 ml of gas and it started but then cutoff within a few seconds thus it is not getting gas.
If it started and stopped then it is likely that you have a plugged up jet in the carburetor or the fuel solenoid on the bottom of the carburetor is not working. When you turn the key to the ON position you should hear a small click from the solenoid attached to the carburetor. If you hear the click then I would rebuild the carburetor first. If it still will not run then I would replace the fuel pump.
JR - I do hear the click when I turn the key to the first position. Do you know if there is a book that covers this engine. I have not rebuilt a carburator in quite some time. Thanks for all your help! Bob
Here is a link to the service manual. Click on download and wait for the timer to expire and then click on download again.
Owner of outdoor power equipment business, repairing all makes and models.