Repair a lawnmower engine that was left exposed to the elements for a year?

Question

I have a lawnmower that I foolishly left outside through last winter. Last year it wasn't in great condition -- it took a ton of very hard of pulls on the cord to get it to start, every single time. I haven't tried to start it this year, but I imagine it has gotten worse.

I think it's a $500-$600 lawnmower new.

Putting aside the motor, mechanically it is in good shape. I don't see any rust. The blade was replaced two years ago. The wheels and everything else are in good working order. I believe the only issue is the motor, which I believe is having trouble due to being left out in the rain and snow.

I am a person who is good with my hands and with machines -- I am a programmer and a woodworker -- but I don't have any experience working on motors.

What are my options for restoring this lawnmower to working condition? (i.e. it starts easily and it runs without major problems).

I am open to dismantling it myself, I am open to replacing the motor, and I am open to bringing it to a repair guy. I'm hoping to be able to repair it for $100 - $200 rather than having to buy new for $500 - $600.

Answer 1

Most common problems have nothing to do with your engine. Fuel, air, and fire are the key ingredients to your mower starting.

1. Fuel - if you left fuel in the tank for more than a couple of months without adding a fuel stabilizer, empty the tank and put new fuel in it.
2. Air - most mowers have an air filter. Look at it and clean it or replace it. It could also be the carburetor as that is where the fuel and air are mixed, but this would be the last thing I would look at.
3. Fire - spark plugs don’t last forever. Replace them every couple of years and make sure the electric wiring is making a good connection

Also, change your oil.

Mowers can be torn down for a thorough cleaning pretty quick (afternoon project). You’d need a socket set, flathead screwdriver, a can of brake cleaner, and nitrile gloves. Funnels and Mason jars are nice for this as well. The cost is really cheap: I lightweight tore down my mower last year and replaced the spark plug, primer, fuel line, fuel filter, and air filter for about $20.

Non-maintenance things that can also make for a hard/impossible start:

1. Bad primer bulb - normally will leak gas when pressed if bad
2. Pull cord and starter - never had this been a problem for me
3. Seized engine - if you can afford a new mower, you probably are better off

Answer 2

First, make sure your engine spins and has good compression. Won't go anywhere without that.

Then, it's all about fuel and spark. First you check for spark by pulling the spark plug, reattaching the spark plug cable, wrap a wire around the plug's threads to the engine's metal chassis, spin the engine, and see if it sparks. No spark, you have a problem to fix.

Dirty spark plugs don't work of course, but sometimes weather can kill a magneto.

Then fuel. Make sure it is good, make sure it is reaching the carb (shutoff valve not turned), fuel pump (if equipped) pumps, then after that, you're into carburetor issues. You can try giving the engine a shot of ether (starting fluid) and see if that makes it momentarily fire in a way it didn't before - that suggests a fuel problem.