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what are the most common problems of a lawn mower not starting? how much compression is there? can you feel the compression if you plug the hole with your finger and crank the engine? how can you test the coil?

In my experience, the most common hard starting problem is stale fuel left in the fuel tank over the "off season."

As the fuel evaporates it tends to clog the small galleries [passages] inside the carb and creates fuel "starvation" when trying to start or run. IF this is the problem it usually requires dissembly and overhaul of the carb.

IF you're lucky you may correct it by pouring all the stale fuel out of the tank, and refilling with fresh fuel to which you've added some Carburetor Cleaner or Fuel Injection and Fuel System Cleaner, both of which are available at any auto parts supply store.

As for compression, you "feel" it quite well when trying to crank the engine while pulling the starter rope handle. Compression causes the resistance you feel. But yes, if the engine has good compression, then during that cranking test the compression will be felt with your finger, and PROBABLY will "blow" air past your finger. You generally cannot "hold back" the compression of any engine.

Even with an electric start engine you can sense the difference by how labored the cranking is with the plug in compared to when the plug has been removed. There will be a difference in the SOUND, and also in the speed at which the engine turns over during cranking.

Most ordinary mower engines do not have a coil, as the spark is created in the Magneto. To test for spark, remove the spark plug, attach the spark plug wire back to the plug, and hold the plug threads tightly against the engine metal to ground it. To reduce the chance of getting shocked, hold the plug with a well insulated pair of pliers, AND WITH a leather glove on your hand.

Then while the plug is grounded, crank the engine and look for intermittent sparking in the "gap" in the plug. Depending on circumstances, is MUCH easier to have a second person helping during the plug spark test.

To tell if there is a lack of compression problem, turn the engine over by hand with the spark plug IN. Then, remove the plug and crank the engine again. Without the plug installed, there will BE NO COMPRESSION. By comparing the difference in the two tests you can tell if there is a problem.

IF it is just as easy to crank with the plug IN as when the plug is out, then there is a problem of lack of compression. I doubt you have that as unless an engine is totally "worn out," there is always compression.

2009-05-16 23:03:27 by sweetmusicman

After removing a lawn mower#39;s fuel tank to access the carburetor, the carburetor can be cleaned with a carburetor cleaner or a simple brush ...

ok i didn't know that lawn mowers took oil. now i can't get the thing to start, i found the oil thing and put oil in it. so what do i do with it now? how do i fix it?

Turn it upside sown and try to turn the blade. If it will turn, the motor has not seized. Did it make a bad noise before it stopped working? If it did, you likely threw the rod and it will not work. Some mowers will shut down by themselves if they are low on oil before any damage is done. Once somebody gave me a mower that she said would not work. I took it home and took out the spark plug to check it. Oil began to run out of the hole. The entire engine was full of oil. That is why it would not run. Make sure that you have the oil to the correct level. Not too much, not too little.
You may be able to fix it.
I had a truck once. The oil plug fell out and I drove it without oil. The engine seized. I filled the case with "marvel Mystery oil" I let it set for a day, then began to turn the motor with a gigantic wrench. It broke free. I gave it a few more rotations and charged the battery. After that it started right up. I changed the oil and it has been running well ever since.

2008-05-14 09:49:24 by jak

My push lawn mower will start, after pulling about 10 times and run for about 10 - 15 seconds and then shuts off. Is this something I can fix. What would I expect to pay to have it repaired.

All the above answers seem pretty good. You should do a general tune-up. New/Clean air filter, oil filter, fuel filter, fuel lines, carburetor kit, good premium gas, change oil, change spark plug... it most likely just needs some tlc

2008-07-17 03:53:01 by Mr. Dee

Price: $26.99 $29.99

Pull cord to hear engine sounds
Clicking key and moveable throttle
Sounds are mechanical, no batteries needed

My lawn mower is a 3.5hp Tecumseh. I have been doing some heavy mowing (tall grass, weeds), and now, the mower will start, and then die after a few seconds of running. I have cleaned out underneath, and it has both oil and gasoline. Do I need a new mower? This is the last season I will need this mower because I am moving to a house with no lawn.

If it still starts, and shuts back off..... its a carb problem 99 percent of the time.....
The float doesn't sound stuck, the main jet (up that hole the float bowl nut goes up) is clogged.... but first make sure gas is getting to the carb at a good rate (take the fuel line off at the carb and let it go real quick)

2006-08-17 07:29:29 by Mary W

hello. my lawnmowers wheel has just fell off so i put it on its side to fix it. i kept it like that for about 3 days or so. now the wheel is fixed and its not starting. im priming it, and it feels like thiers no oil priming. there is oil, and gas. what do you think i should do? do you think that the oil drained into the motor? can i fix this or no?

I'm betting the carburetor diaphragm or needle and seat allowed raw fuel to enter the combustion chamber when you tipped it on it's side.

Remove the air cleaner so that the intake manifold has a chance to dry out.

Remove the spark plug and let the combustion chamber dry out. Pull the starter rope many times to speed up the process. Replace the plug if it looks the least bit dirty, wet, oil fouled or has burned electrodes.

2008-07-08 11:30:56 by j03yriot