Lawn Mower Engine Surges Up and Down

The engine revs up and then down and up and then down and it doesn’t stop and is downright annoying not to mention that it affects the power output of your lawn mower.

This surging is normally caused by a fuel problem or more specifically, a lack of fuel problem. Something is preventing the gasoline from getting into the engine.

Most likely it is a plugged up idle jet that is causing the fuel not to get into the engine. Idle jets are smaller in size and plug up more easily. So the carburetor will need to be taken apart and thoroughly cleaned. You also want to make sure that there is no air leak where the carburetor attaches to the engine or in the intake as well. An air leak will cause this surging as well.

Now you can reassemble your carburetor onto the engine and then test it to see if it has fixed the problem. You should have no more surging and it should run smooth like it should in normal operation.

If it does not, you may have to replace the carburetor as that is the best course of action if you cannot get it completely clean.

Lawn Mower Engine Surges up and Down

Do you ever wonder why your lawn mower engine revs up and down? The annoying sound that also affects the power your lawn mower puts out is caused by a fuel delivery or vacuum leak issue.

The engine gets enough fuel and then it doesn’t and so on and so forth. After a while the mower will develop a more serious engine problem and may begin to hard start or not even start at all. The surging could also become worse and the swings between high and low will get longer in duration.

This is a problem that is best suited for a lawn mower engine specialist to check out. Our Locations page has a listing of lawn mower repair shops in your area to help resolve this problem for you.

You can check the easy things such as slightly cracking the gas cap to see if the surging stops or change or clean the fuel filter if it has one. Some fuel filters are in the tank and not easy to see. You may have to drain the tank and then flush it out.

The other items are the carburetor and gaskets. Fuel lines can be the culprit too. Systematically check these items for blockage and air leaks to find the cause of the problem.