What causes my lawnmower engine to surge when hot?

My 14 month old lawnmower surges and eventually quits running when hot. I called Toro & the factory service center said they can’t work on it for 5 weeks! I’m supposed to try to fix it by myself!

I’m going to clean the spark plug today and either drain & replace the gas or put additive in it. What else should I do?

  5 answers
  • Lynn Sorrell Lynn Sorrell on Jun 25, 2019

    THese simple things you can check fix yourself. clogged fuel filter(replace),spark plug(s) need cleaned,bad/old gas causing carbeurator to gunk up(do you drain when in storage;water/grass/dirt/dust in it;carburetor needs to be cleaned out, a can of carbeurator cleaner spray(auto parts stores) can dissolve the crud out and restore operation. 90% of this problem is caused by old contaminated gas. ),check muffler---it quits running as a safety precaution so it won't destroy the engine.

  • Hi, Cheryl!

    Seafoam is an additive that helps remove gunk and such from engines. I use it in my car and my mower before changing the fuel filter. I hope this helps!

  • Lucy Marie Bernier Lucy Marie Bernier on Jun 28, 2019

    Check oil .

  • Lifestyles Homes Lifestyles Homes on Jun 28, 2019

    Thanks everyone.

    Gas wasn’t old. Ran it dry last Fall. New gas can.

    Oil was clean & full. Air filter new.

    No fuel filter.

    SOLUTION: Siphoned out all gas, Cleaned spark plug with 70% isopropyl alcohol, put Sea Foam in fresh gas.

    Didn’t install the new in-line fuel filter I bought before I said, Why not try it and see?

    SOURCE OF PROBLEM: sheeting rain storms. Even though it was under a 6’ deep porch, sideways rain storms got water in the carburetor.

    PREVENTION: 30 bushel galvanized bucket upside down over the top of the mower when parked.