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I have a John Deere lawn mower with a 17hp Kawasaki v twin it will not start. The ignition coils are not firing can both coils go out at the same time? Please help

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Not likely. I'd look at the ignition control system. Used to be a distributor with points. It is probably a bad connection to sensors, that feed data to the ignition control system. Prime is probably the flywheel position sensor. Make sure all connections are clean with bright metal from scraping. If no help the sensor/s may be bad, or the computer itself. I'd get a Repair manual from the dealer or Mfg website, or since you seem to be inclined to DIY. and may need it later anyway.

Posted on Mar 28, 2015

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Never replace just one of the coils always replace both at the same time if that's the case of no fire, take it to your local lawn and garden shop for a check to see, they might charge you for a small diagnostic fee but its better then dealing with the headache alone

Posted on May 17, 2015

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I have that same engine. I found mine to be sensitive to low battery voltage when cranking. The battery tested at 13+ volts but when cranking the level fell too low for the ignition to fire off. Old batteries might do this. New battery fixed it.

Posted on Apr 26, 2015

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Both coils will rarely go out at the same time. HOWEVER, there are a number of situations that will keep both coils from firing.

For a more precise answer about your machine please include Make/Model/Year/Engine Model/Deck Size, and hours on meter if you have one. A short description of the events preceding the beginning of the problem is also helpful.

When a person says "I am not getting any spark", we have to assume this means the engine cranks whenever you turn the key. Or, it spins whenever you pull the rope.

A mechanically functional (meaning all the internal parts are working, i.e. pistons, valves, etc) engine requires a steady flow of three things, air, fuel, and spark in order for the engine to start and run. These are the trinity, or triad of a happy engine.

If you are in fact not getting spark, after you crank the engine, or pull the rope for a while, you should begin to smell the un-burnt gas passing through the engine. This is a good indication that you have gas flow and air is making it through the carburetor. That is a good thing. It is verification that you have air and fuel, but no spark. If you do not smell this fuel after a bit of cranking you may have fuel problems. Keep in mind that if you smell this fuel it means the cylinder(s) are now flooded and it's time to back off the choke and crank it in the run position.

BEFORE you begin your tests, consider the engine kill system. Modern day safety systems include a kill wire. This will be a single wire going to a connecting terminal on the coil. The wire is small and can be disconnected. Disconnecting this wire isolates the engine from all the possible bad switches, relays, diodes, and wiring setup designed to kill the engine if safety procedures are not followed. SOOO, you may want to run the spark plug test explained below, without taking off the engine shroud and disconnecting the kill wire. If you get a quick fix, great!

If there is no quick fix you will need to remove the shroud before going through the rest of the tests. You must find and disconnect the kill wire, then begin your coil and spark plug tests again. If the engine starts and runs after taking off the kill wire, then you have a chore in store. You will have to track down the faulty part in your safety system. If there is a problem with any of your safety switches neither coil or plug will spark.

Note: it is likely, with a disconnected kill wire the engine may start, but when you turn the key off, or otherwise try to shut the machine off, the engine will keep on running. Just slip the kill wire back on, or otherwise ground the terminal. This will kill the engine, or wait till it runs out of fuel.

Providing spark to the engine is one of the simple systems and relatively easy to diagnose. Start with the spark plug. You CANNOT test a spark plug (without expensive equipment in your lab). For instance, did you know that it takes more juice to create a spark under compression than it does at normal atmospheric pressure? So just because you have a visible spark from the plug outside the cylinder does not mean you have a usable spark under compression.

The ONLY answer to this end of the problem is to get a new one; even if the current one is not very old. Briggs & Stratton recommend changing the spark plug annually however a spark plug can fail at any time. The spark plug sits in the cylinder and is subjected to compression, high heat, explosive forces, constant vibration, and of course electric shock in the 15,000 volt range. Make sure the gap is set correctly on the new one, typically 0.76 mm (0.030 in).

If you want to know why you should just throw in the towel and start with a fresh spark plug, go here and read this wonderful essay on spark and spark plugs.
Village Science Magneto Spark Plugs

Now you have your new plug, its properly gapped but the engine still won't start. Next up is the Magneto or Coil. If you have not already done so, pull the shroud, or fan cover, from the top of your engine and you will see a heavy metal wheel with fan blades. This is the Flywheel/Magneto. It has permanent magnets embedded in the side. As the magnets fly passed the coil, current is generated. Seldom do the magnets go bad, but you should feel a strong attractive force of the magnets when you hold a screwdriver about an inch from the magnets. If they do not seem to be very strong you might have to replace the flywheel. This is a very rare happenstance.

Follow your spark plug wire back to the small metal thingy, mounted next to the flywheel, now you are at the Ignition Coil; or just Coil for short. TWIN cylinder engines have two Coils; one for each plug. A coil generates the 15,000 volts required by the spark plug. The Coil must be a precise distance from the flywheel. This is the Ignition Coil Gap. This gap usually .20 mm to .30 mm (.008-.012 in) from the flywheel. To set this gap properly, the magnets on the flywheel must be right in front of the coil when you set the gap.Check your specs. If the gap ain't right the spark ain't bright.

With the exception of the kill wire which is designed to stop the Coil from working, the Coil functions entirely independent of the rest of the wiring systems on the machine. If you disconnect the kill wire and the coil is good you will get spark to your engine regardless of the condition of the rest of the entire wiring system. The Coil works all by itself; it makes its own electricity. It does not need the battery or the key switched on.

Inside the Coil are two windings of wire and no moving parts. With shorted (melted together inside) windings you can still get a spark, but it will be weak.With open (burnt/broken) windings, you get no spark at all. There are also electronic components like diodes which may be failing. Coils are subjected to heat and vibration and do fail on occasion. Another coil consideration is the spark plug wire. Back in the day, we would replace all our spark plug wires when we gave our car a tune up; because spark plug wires do fail. The only way to replace the spark plug wire on a mower is to replace the Ignition Coil.

Note: Coils may not fail completely at first. They can be complicit in the situation where a mower starts and runs for a while. As it heats up the coil parts expand and cause the engine to shut down. It does not re-start until the machine has cooled enough to allow the coil to cool. This can be 30 minute to several hours; perhaps it starts again the next day only to repeat the failure.

Short of a well running engine, with no special equipment, the only field-test for a coil and the spark plug wire output is to visually assess the color of the spark. Alternatively, you may use a spark tester (everyone should have a spark tester, they're cool and cheap). A spark tester gauges the strength of spark by making it jump a bigger gap. This test calls for a gap in the range of 4.2 mm (0.166 in). It's important to note that setting a test gap beyond 5.0 mm (0.200) could damage the ignition components. Briggs and Stratton manuals, for the newer engines, specifically state that you should not test for spark with the spark plug out. I do not know why this is. They specify you should use a spark tester.

B&S notwithstanding (at your own risk), with a new plug attached to the plug wire hold the threaded part against a ground point or wrap some bare copper wire around the threads and fasten the wire to the engine frame or other good ground. Make your shop or garage dark so you can see the spark easily, then crank the engine. The flywheel must spin rapidly (at least 350 RPM). The strength of the spark is revealed in the color. A red or yellow spark is weak and probably will not spark in the cylinder. A blue or white spark is strong and has enough voltage to fight across the spark plug gap even under pressure within the cylinder.

Note: a good strong spark also makes a strong snapping noise as it fires. With the kill wire removed and the Coil gapped correctly, if there is no spark at all with your new plug (try two new plugs in case one is faulty) it may be time to replace the coil.

One final note: On a twin cylinder engine you may have one side firing and not the other; quite common actually. You have the option of switching parts from one side to the other to help diagnose which part is bad. The spark will follow the good part; lack of spark will go with the bad part. It's important to note at this point, IF the safety system is at fault, neither side will spark. That's a clue.

That about covers it for diagnosing and curing a weak spark or no spark problem. In order to help you trace or check for problems in the safety system, I would need to know the Model and year of your machine. Is the transmission hydraulic? Do you have an electric clutch? Anything connected to the electrical system can impact the kill wire of the coil and prevent the coils from firing. Village Science Magneto Spark Plugs

Posted on Mar 28, 2015

  • 2 more comments 
  • cory Mar 28, 2015

    Thank you it is a John Deere x300 series 2009 model I unhooked the kill wire and it started. But now my mower/pto will not engage is there a way to bypass the sensor

  • Kprime
    Kprime Mar 28, 2015

    Hi Cory. Post your question as a new question so I will have room to write the answer.

  • Kprime
    Kprime Mar 28, 2015

    John Deere x300 series 2009 model I unhooked the kill wire and it started. But now my mower/pto will not engage is there a way to bypass the sensor?

  • Kprime
    Kprime Mar 28, 2015

    like that


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Posted on Jan 02, 2017

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SOURCE: I have a John Deere Riding lawn mower which starts

Hello roobar2009:

>>From your Description it Sounds like a Carburetor Problem, a Bad Fuel Filter or Bad Gas.
>>If you have Changed the Filter and the Gas and the Problem is Still happening, then
>>The Following is a Simple Way to make Sure the Engine is Getting Gas from the Carburetor to Run.
>>If the Engine Starts and Quits, then Check the Carburetor Solenoid.
>>If the Carburetor Solenoid is Good or has been Removed and the Engine will Start and Quit when the Gas is Poured into the Carburetor Throat, then Soak and Clean the Carburetor.
>>The Following is a Basic File I Made for Cleaning Carburetors. Any Input is Appreciated. Even though the Carburetor Looks Clean, the Internal Passages May be Restricted with Varnish that Gas Causes to Build Up over Time.
>>Spray Cleaners Remove this Varnish in Layers, so Soaking is the Only Sure Way to Remove ALL this Varnish.
>>I have Found that Most People can Use a Breakdown/IPL and Disassemble the Carburetor Enough for Proper Cleaning.
>>You Only have to Remove the Bowl (if Applicable), Float Pin (if Applicable), Float (if Applicable), Needle Valve.
Remove Any Adjustment Screws that Go Into the Carburetor Body. The Welch Plugs Do Not have to be Removed.
>>If you are Able to Remove and Disassemble the Carburetor and Keep the Gaskets Intact, then Usually these Gaskets can be Reused. The Only Parts you May Need to Replace is the Needle Valve.
>>The Float Needle Usually is Not Replaced Unless it is Not Operating Properly (the gas flow not shutting off and the carburetor is Flooding). Do Not Remove the Main Nozzle. This is a Pressed Fit and Removal is Not Required for Cleaning. Soaking and Blowing the Carburetor Out After Soaking will Clean the Nozzle.
>>Once Disassembled, then Soak the Carburetor Body and Parts in a 1 Gallon Can of Gunk Carburetor Cleaner Overnight. The Can has a Parts Tray Inside it for the Small Parts.
>>Once the Carburetor and Parts are in the Cleaner, you can Replace the Lid for Safety and to Prevent Accidental Spillage. Then Blow Out the Passages with Compressed Air.
>>***(Do Not Use High Pressure Air for the Zama Carburetors, they have Check Valves for the Primer and these are Usually Blown Out of the Carburetor if Not Careful. Allow the Zama Carburetor to Set on a Drip Pan and Dry)***.
>>****All the Carburetor Adjustments are the Same for Lawn Mower and Trimmers. There are Several Location for the Air Mixture Screws. The Idle Air Mixture Screws are Usually Located at the Top of the Carburetor Bowl and the Top of the Carburetor Body.****
>>If the Main Air and Idle Air Mixture Screws are Side by Side on the Side of the Carburetor, then the Idle Air is Nearest the Engine. The Main Jet Air Mixture Screw is Located in the Bottom of the Carburetor Bowl or Beside the Idle Air Screw on the Side of the Carburetor Body.
>>Some of the Older Model Carburetors have the Main Jet Mixture Screw Straight in from the Top of the Carburetor Body (this is Rare anymore). If you have Cleaned the Carburetor (Disassembled and Soaked Overnight in Carburetor Cleaner (I Use Gunk). Then Blow Out the Passages with Compressed Air and Install a New Kit if Required. Now Setting the Air Mixture Screws:
>>****Turn the Idle Air and Main Air Mixture Screws In Until SNUG **Do Not Jam** Then Reverse Both Screws 1 1/2 Turns. Holding the Throttle Full Open, Start the Engine. Turn the Main Air Mixture Screw Clockwise Until Proper Revs are Obtained. Occasionally you May have to Turn this Counter Clockwise to Achieve the Proper Revs. Now Allow the Engine to Idle. Set the Engine Idle Screw (Not Idle Air) so the Engine will Stay Running if Required. Now Set the Idle Air Mixture Screw so there is No Hesitation when Throttling from Idle to Full Throttle. Reset the Engine Idle if Required.****
>>If This Carburetor has a Single Air Adjustment (Except Tank Mounted 9200 and 100900 Engine Model Carburetors), Use the Section Above that Pertains to Full Throttle RPM Air Mixture Screw and then Adjust the Screw if Required to Eliminate Any Hesitation when Throttling from Idle to Full Throttle.
>>For the 9200 Model Tank Mounted Carburetor Adjust the Air Mixture Screw Full In, then Reverse 1 1/2 Turns. Set the Throttle Lever to Full Throttle and Start the Engine.
>>Now Carefully Use 1 Finger and Open the Throttle Plate and Over Rev the Engine Slightly. If the Engine Over Revs and Does Not Struggle to Over Rev, then the Carburetor is Set. If the Engine Struggles to Over Rev, then Turn the Adjustment Screw In 1/4 Turn and Repeat the Over Rev Test.
>>If you Adjust to 1/2 Turns In and the Engine Still Struggles to Over Rev, then Return the Adjustment Screw to 1 1/2 Turns Out from Snug and Turn the Screw Out 1/4 Turn. Do the Over Rev Test. Continue this Process Until you have the Engine Over Revving without Struggle.
>>By Adjusting the Carburetor on this Style Carburetor Until the Engine Over Revs without Struggle, you have Adjusted the Air Mixture to the Best Possible Setting.
>>This file was Intended to Give you the Basic Carburetor Cleaning Instructions and May Not Reflect Your Carburetor Components.
>>If you have Questions, Please Ask. The links above Provide Good Directions on Cleaning the Carburetor. Make sure you use an Compressed Air to Blow through all the Carburetor Passages to make sure they are Clear.
>>2- .
Please, Do Not Hesitate, If I Missed Something or you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance.
Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Be Safe and Be Happy. Thanks.

Good Luck


jbridger (John)

Posted on May 17, 2009

  • 10865 Answers

SOURCE: john deere 420 trouble starting getting gas and

The engine needs air, so be sure the air filter is clean. If it is not, replace it.

The engine needs spark. Replace the spark plug and be sure that the battery has a complete charge.

The engine needs good fuel so be sure the gas is newly purchased, not gas that has been sitting around for months.

Posted on May 19, 2009

  • 229 Answers

SOURCE: I need a wiring diagram for a 210 John Deere

try you might be able to get them there or call your local dealer.

Posted on Sep 14, 2009

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