Question about Garden

2 Answers

Will crank but fowls the plugs out without choking and will not fire

Posted by on


2 Answers

  • Level 2:

    An expert who has achieved level 2 by getting 100 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.


    An expert that has over 500 points.

  • Garden Expert
  • 187 Answers

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 engines 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 not 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 that you have your new plug, properly gapped and it 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. 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 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.
Village Science Magneto Spark Plugs

Posted on Apr 07, 2015

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    Top Expert:

    An expert who has finished #1 on the weekly Top 10 Fixya Experts Leaderboard.


    An expert that got 20 achievements.


    An expert that got 10 achievements.

  • Garden Master
  • 49,197 Answers

Check for flooding in the carby-- faulty needle and seat and float

Posted on Apr 07, 2015


2 Suggested Answers

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

A 6ya expert can help you resolve that issue over the phone in a minute or two.
Best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
The service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
Good luck!

Posted on Jan 02, 2017

  • 257 Answers

SOURCE: Runs for 5 seconds with choke pulled;no crank without choke

check your fuel pump to see if working,, then clean or replace carb,, and do tune up on it,,, hope this help you,, good luck

Posted on Aug 15, 2009

Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I got a polaris sportsman 500 HO I changed stator ignition and spark plug now it cranks fine and idols good but when give has it boggs and back fires can someone help with this

Check air filter make sure its clean, fuel lines are clear and filter clean or new, is the gas old? Carb or injector? if carb possible needs cleaning. could also be fowled plug

Sep 03, 2015 | ATVs

1 Answer

Replace sensor it gets a groove worn in it

there is supposed to be an air gap between the sensor and the rotor so if it is wearing out then the gap is not there. This will also be a problem for the running
If it is just one plug that is fowling (oil or fuel) the go to a spares shop and get a hotter plug to burn off the fowling
Plugs come in heat ranges from cold to hot and are used specifically when problems occur.
also replace that HT lead as they break down in the centre and don't fire properly

Mar 08, 2015 | Cars & Trucks

1 Answer

How do you start a 19th mtd riding mower

Put your left foot on the clutch pedal and push down all the way on the clutch. Move the throttle lever all the way to the top, this turns on the choke. Turn the key clockwise, to the right, to start the engine. Once the engine has started, move the throttle lever down to turn off the choke. You only need the choke when the engine is cold. If you use the choke while the engine is hot, you can flood the engine (too much gas) and this will fowl the spark plug. If you have flooded the engine, turn off the choke by lowering the throttle lever and try to start the engine a few times. If the engine doesn't start, then you may need to wait 20 to 30 minutes before trying to start the engine again. If the engine still does not start, then you can remove the spark plug to dry and to clean the spark plug. With the spark plug out, turn the key to the start position for 10 seconds, to push out excess fuel and fumes. Replace the spark plug and try starting the engine without turning on the choke.

Oct 08, 2014 | Garden

1 Answer

Mower will run then starts running bad turn the choke off and it stalls stalls after i choke it also blows gas out of the top of the carburator how do i adjust the vaalvesType your problem for a solut

Using the choke as you did,mentioned in your problem,you have flooded the carburetor. DO NOT USE THE CHOKE,ONCE THE TRACTOR IS RUNNING. Choke is used to start the motor only. When you run with the choke on,the motor gets to much gas and the plug(s) get fowled up and gas comes out of the carburetor. Remember the motor is hot,when gas comes out of the carburetor,the amount of over flow (flooding),could cause a FIRE. Lay off the choke,clean the spark plug(s),they will most likely be fowled up. The filter will be soaked with gas,remove the filter,soak up the gas,using a handy wipe,let filter dry out. Once dry replace filter. You should be good to go. Remember,do not over choke,use when starting a cold motor,usually when motor is hot from running,you may not have to use the choke at all. Hope this helps. Sincerely,Brad Locke

Apr 22, 2013 | Craftsman 21 hp 42 in. Deck Yard Tractor -...

1 Answer

Can't git engine to fire know fire from coil.

Rechk plugs firing order. chk soliniod and coil r ok, rechk fuel is getting into engine- choking usually determines that, u can smell the over choked engine. I f engine turning & choked hold throtel to floor while cranking and leave there until it fires. if no firing happends it must be electrical. rechk electrical connections. Cheers

Sep 06, 2012 | 1989 Nissan Pathfinder

1 Answer

What should I do with my husqvarna 130BT because I put in too much oil with the gas and it won't start?

First, you need to dump all of the fuel out of the gas tank, Preferrably into a gas container. If you know how much oil you dumped in, you can calculate how much more gas to add. You could also just dump the gas, re-mix some new gas and oil, whichever you prefer.

If you are comfortable doing this, remove the fuel lines going to the carberator and let them drain into a pan. Pump the fuel primer to purge the gas out of the carburator, and then re-install the fuel lines. This might help you get it started a little faster, but its not necessary. You can burn the old gas in the engine at it will be fine.

Next, remove and replace the spark plug. Its probably fowled out with too much oil. Keep a can of carb cleaner and a small wire brush handy, you may need to clean the spark plug a couple times. If it gets too dirty, you can replace the spark plug with a new one. Do not burn Carb Cleaner in your engine for long periods of time, it will damage the engine.

After you have installed the spark plug and put some correctly mixed gas in the tank, Try to start the engine again. There will be some residual fuel in the fuel lines going to the carberator, so you will need to burn off that gas.

If you can't get it to start, try these steps:
Choke off, throttle wide open, crank several times. (or let it sit in the sun for a couple hours) (this corrects flooding)
Prime carberatur, Choke full on, throddle idle position, crank until it fires once but does not start.
Choke half, crank until it fires again or starts.
If it starts skip this step: (Choke off, crank until it starts).
Keep the choke on half for about 10 seconds and let it idle.
Put the choke off and let the engine warm up for a couple minutes.
After warmup, test the throttle to see if it will run at full throttle (it may take some fluttering until the engine is fully warmed up)

Let the engine run at full throttle for a few minutes. The exhaust may be a little more blue-smokey than normal...this is the excess oil burning...totally normal and harmless.

Mar 25, 2012 | Husqvarna Garden

1 Answer

Have new 450 and is very difficult to start. Lost or didn't get book. How do I start it and re-start it while still warm??

Start procedure is, push the primer as many times as it takes to 3/4 fill the bulb ( you cannot over prime it ) pull the blue choke lever fully out,place the saw on the ground with your right boot through the back handle, crank the engine until it fires once, do not continue to crank the engine with the choke out ( they will not run on choke, only fire ) push the choke fully home, crank the engine until it starts, blip the throttle trigger to bring the saw to idle, warm engine, pull the choke fully out and push in again without cranking engine, this will engage the part throttle, crank the engine until it starts, blip the throttle to bring the engine to idle.

May 18, 2011 | Husqvarna 450 e-series 18" Chain Saw

1 Answer

Runs for 5 seconds with choke pulled;no crank without choke

check your fuel pump to see if working,, then clean or replace carb,, and do tune up on it,,, hope this help you,, good luck

Aug 12, 2009 | Husqvarna Lawn Tractor - 54in. Deck, 26...

1 Answer

Crank no start yzf 600r

Inject some carb cleaner spray through the opened air filter while cranking.
Spark plugs work? timing on the camshafts ok?
Crank it without turning the throttle on.
Pull the choke cable if you need to.
It should fire up without throttle.
Use the carb cleaner spray to help it (don't spray too much.It will backfire from the carbs).

Jun 15, 2009 | 2005 Yamaha YZF 600 R thunder cat

Not finding what you are looking for?
Garden Logo

Related Topics:

96 people viewed this question

Ask a Question

Usually answered in minutes!

Top Garden Experts

Dennis Key
Dennis Key

Level 3 Expert

2478 Answers


Level 3 Expert

666 Answers

john h

Level 3 Expert

12744 Answers

Are you a Garden Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides