View Full Version : My new mower keeps back-firing

01-18-2004, 01:50 PM
I've had the mower less than 2 months and now it will not start, but it will back-fire. It's a 14 Kawasaki if that helps. What can I do to correct the problem? Thanks in advance.

edit- so far i've taken the air filter and blowed it out, still doesn't help. should i soak the outer liner with fuel to get it started?

01-18-2004, 01:54 PM
Take it back to the dealer!!

DFW Area Landscaper
01-18-2004, 02:00 PM
My 13 HP Kawi back fires all the time. Only when I pull the rope to start it, though.

Has never failed to start. Used to start cold with one pull. Now it usually takes two or three pulls, warm or cold.

DFW Area Landscaper

01-18-2004, 02:02 PM
It's been smooth as silk thus far, and I would take it to the dealer but it's Sunday and tomm is MLK day.

01-18-2004, 02:05 PM
Sounds to me that your float is stuck. Remove float bowl and check.

Critical Care
01-18-2004, 02:20 PM
You may also want to check your fuel filter, or filters. Sometimes they stick one on the end of the fuel intake down inside of the fuel tank. Had a problem with a Walker mower that turned out to be one of these little devils. Actually, even when they don't look dirty they can still cause problems.

01-18-2004, 02:25 PM
Good point critical. PCLL, Easiest way to check fuel filter restriction is to pull fuel line off at carb and see if fuel runs out at a good, constant rate. May need to run engine while doing this if equipped with pump so do it quick

01-18-2004, 02:48 PM
narrowing down these problems is usually fairly simple. It is usually spark or fuel. Check filters first just to make sure the fuel is getting to the carb. If you dont have fuel replace fuel filters, if you have fuel try cranking without air filter. If engine cranks replace air filter. If the engine doesnt start, remove plug and check for spark. If no spark, is plug wet or fouled, if so install new plug. If not check for spark where the wire connects to plug, if you have spark at the wire but not at the plug ,replace plug. If engine still wont crank and you have spark and fuel it might be that the keyway in the flywheel is sheared or partly sheared which would effect timeing. Replace keyway. This shouldnt be a problem unless you hit something while mowing. Other problems might be low oil level since most new engines have an oil sensor or a bad sensor. Weak spark might mean a bad coil or a wire is grounding out, this happens a lot with electric start. Also if someone has been messing with the carb adjustment screws , the carb may be way out of wack. Consult owners manual for proper adjustment. I have found most times it is either a fuel filter or a spark plug., those inline fuel filters are bad to get stoppedup so I changed mine out to a larger automotive type.

01-18-2004, 03:05 PM
Thanks guys, I purchased a new plug, lets hope this works.

01-18-2004, 03:07 PM
Not likely a fuel starvation problem. If it were fuel related it would more likely be to much fuel not to little, so I would not start at the fuel filer. I would check and see if a piece of carbon was between the electrodes on the spark plug, check to that there is no moisture in the spark plug boot, check to see that all the connectors and wires for the operator pressence safety cr@p are tight , if these don't fix it I would check all the wires and ground to the electronic ignition coil and module as well as the gap between the coil pickup and the flywheel. Let me know what you find. Tom

01-18-2004, 03:07 PM
bet its the fuel filter

01-18-2004, 03:35 PM
bet its not

Metro Lawn
01-18-2004, 03:38 PM
It's the plug.. Happens every now and again on Kaws

01-18-2004, 03:46 PM
ITS new I would load it up and have it back at the dealer thats why you pay for a warrenty


01-18-2004, 03:50 PM
could be a lot of different little things like loose wires ect, but why would you tell him not to check the fuel filter first. It fast, free, easy to do, and alot of the time the problem. He is getting a backfire so I assume he is getting spark, altho we dont know how much of a spark, so it could be a loose wire just letting it fire when it makes contact. If the engine is getting fuel, spark and is in time and has compression it will run. Its 2 months old so it shouldnt be worn out, unless he hit something it should still be in time. If its getting to much fuel the plug will be wet and wont fire. Wires do get loose but the filter is the easiest thing to check first. Maybe he can post again when he finds the problem and let us know what it was.

01-18-2004, 04:40 PM
should i soak the outer liner with fuel to get it started?

Do not do that! if it back fires thru carb you will have one heck of a expensive weenie roast

01-18-2004, 05:23 PM
Originally posted by SHOW ME STATE RIDER
Take it back to the dealer!!

I agree 100%. I have a 4 month old TTHP 48" 17 Kawi e/s that has been back to the dealer 2 times and will go back again if it needs to. I feel if you pay big bucks for a piece of equiptment, IT WILL BE RIGHT. It's ok to check little things if you want to but be careful you don't mess something up and then expect the dealer to fix it for free under warranty. Good luck.

Richard Martin
01-18-2004, 06:11 PM
I agree with a few others here. Just take it back to the dealer.

But of you insist on working on it then:

Pull the airfilter off and spray one quick shot of starting fluid in it. If it starts and then dies it's a fuel/carb problem. If it won't start it's a wiring/ignition problem.

There also are no adjustments on new Kawasaki carbs to get messed up or adjust so that can not be a problem.

I wouldn't worry about the coil because coils usually manifest their problems after they get hot. Kaw 14s don't come from the factory with low oil sentry although it's not a bad idea to check the oil level.

01-18-2004, 06:30 PM
no questions asked take it back to the dealer.

01-18-2004, 06:33 PM
Have you checked the oil??? If it will not start but backfire you may have the crankcase filled with fuel and spitting into the carb. Regardless, take it to the dealer.

01-18-2004, 07:50 PM
I replaced the plug and it started on the first pull. NOw, seeing as I've only had the mower a few months, should I suspect something wrong since it burned a plug so soon? It's a Bunton mower, so I'm expecting the best.

Eric 1
01-18-2004, 07:54 PM
If you are using cheep gas that may be a problem,or if you run it long and hot it may have had the rong heat rang plug in it.

01-18-2004, 07:57 PM
I did a 15 hr leaf clean-up with it last week, I also run 87 octane, so you're probably right.

Eric 1
01-18-2004, 08:01 PM
Wow ....a 15 hr leaf job!better you than me.I hope they paid good for that.

p.s.If you haven't you may clean your air fillter, all that leaf stuff in there will plug that up and give poor power.

01-18-2004, 08:04 PM
it was a mess to say the least. about 4 acres worth. i shouldn't say it was all leaves for 15, but the entire clean-up took 15.

Eric 1
01-18-2004, 08:13 PM
Ok i see.Still thats alot off leafs at one place.Or maybe all my stuff is smaller than yours.My biggest is about 2-3 hrs and that seems like forever to me.

More power to you.

I try to pulverize the stuff with my mower as mutch as possible before i blow and bag it all.

btw, was that a one timer or a contract job. sound nice and expensive.lol

01-18-2004, 08:18 PM
it's a waterfront property. i'd venture to say the house/land is worth 2-3 million.

and yes, it's now a weekly acct valued at a whopping 480/mth.

pulverizing- well, i thought about letting the gators do just that, still i would've had to go over it a few times. imo- it was better to slow down and do it right the first time, as opposed to leaving a crazy eight pattern all over this guys lawn.

01-18-2004, 08:24 PM
I am glad you found your problem, thanks for letting us know what it was. I have seen bad plugs right out of the box. I would use better gas, Chevron or Texaco.
65 Boss, great idea about checking the crankcase for gas as I have seen this also with a sticky or dirty float, I have seen it lock the motor up with fuel. I would hate to think if it did run with the oil dilluted with gas.
Mudstopper, I gues I won the bet as it was ignition related not lean fuel. If you read my post you will see that I told him that I would not "start" with fuel. To get a back fire in my experiance it takes either incorrect valve timing[ a valve is open ] incorrect ignition timing or to much fuel [but not enough to foul the plug.

Eric 1
01-18-2004, 08:25 PM
Well in that case thats what i would do for $120 a week.Good image to,your right.

p.s.I hope that i did not offend you there on the w.b. post sorry for that.I dont know you land.If a w.b. makes you money thats great.Maybe a velkie though for 4 acres!!!lol

01-18-2004, 08:30 PM
If your spark plug fouls again, take the mower back to your dealer. There is probably a carbureator problem causing the backfire/plug fouling problems. Don't continue to run the mower if the condition persists or serious engine damage can occur. Backfiring can and will burn intake and exhaust valves very quickly in aircooled engines. Good luck.

01-18-2004, 08:39 PM
i didn't take offense eric. like i stated, imo ztrs don't do well on inclines, otherwise they're great for wide open spaces.

velkies- i just retired a 93 honda hydro 48, it had a velkie- what a peice of crap. i purchased a new bunton and i couldn't be happier.

edit- thanks dennis, thats what i was looking for.

Metro Lawn
01-18-2004, 08:44 PM
Gee.. I was right I guess it was a good thing you didn't your time to haul it back to the dealer and look foolish over a $1 plug. This is a common problem and it has nothing to do with the machine... It is the plugs.. some last years other only a few weeks.. They do make bad plugs, just like bad mowers. I feel bad for you guys that want to run off to the dealer any time something happens.. Even if they stop what they are doing and jump right on your machine.. for something this simple they may get upset.. It's like the boy who cried wolf.. When you really need them they may just put you on the back burner.. just a thought

Eric 1
01-18-2004, 09:16 PM
Hey pcll,were in Dixe are you?If you dont mind

01-18-2004, 09:17 PM
Dishboy, I concede to your expertise. But if you read my first post I suggested checking the fuel filter first and then the plug. I will continue checking my filters first since it is free and easy and usually causes me more problems than the plugs. Changeing plugs first cost money and doesnt always cure the problems. A clogged fuel filter is more obvious to spot so you wont change it unless it needs it.

01-18-2004, 09:41 PM
mobile alabama here.

Eric 1
01-18-2004, 09:43 PM
Cool my grandmother lives there,nice spot.But she has been flooded 2 or 3 times.

N.E Gorgia 2 hrs north Atl.

01-18-2004, 09:44 PM
I have the 14 hp Kawasaki on my Bunton, when I first got mine it would do the same thing, it would foul plugs. What I found happening was that when I moved the throttle lever to the "CHOKE" position to start it, and after it started, I would move the throttle lever into the "FAST" position. I noticed a very, very small amount of smoke coming from the exhaust, even though it was not in the "CHOKE" position, the choke was still partially engaged enough to foul the plugs in a few hours. Once I figured it out that I had to come past the indent to disengage the choke I never had the problem again. Hope this helps.

01-27-2004, 02:20 AM
i have the same prob on my W/B... but mine back fires only when shutting down.... 12.5 Kawi .. it starts first pull.. and no other signs or symptoms......even if i idle it down let it sit for a min then shut it off, still ....BANG! any ideas? oh ( new plug, new fuel, filters are clean )

01-27-2004, 10:32 AM
Originally posted by KevlarLawnCare
i have the same prob on my W/B... but mine back fires only when shutting down.... 12.5 Kawi .. it starts first pull.. and no other signs or symptoms......even if i idle it down let it sit for a min then shut it off, still ....BANG! any ideas? oh ( new plug, new fuel, filters are clean )

All Kawi's do this, especially when new. They need to idle down for longer than a minute to keep from backfiring. Over time with more hours it will not do it as bad or as often. I let them sit for a few minutes while I blow everything off. It will get better with time.

01-27-2004, 01:29 PM
Originally posted by KevlarLawnCare
i have the same prob on my W/B... but mine back fires only when shutting down.... 12.5 Kawi .. it starts first pull.. and no other signs or symptoms......even if i idle it down let it sit for a min then shut it off, still ....BANG! any ideas? oh ( new plug, new fuel, filters are clean )
I had this problem on a 25 horse Kohler. It was an older motor but I had just had my my dealer tune it up. It had never backfired before. My solution suprised me when I found it. The bottom of the muffler had slowly rusted some small holes in it and over time, I had not noticed the increased noise level. I took a wire welder and filled in the small holes and it did not backfire anymore. Either that ot it was muffled. But even muffled, I would think I would have heard something.

Critical Care
01-27-2004, 01:48 PM
Yep, I had a Kohler on a Toro w/b that would backfire at times after turning it off. If the engine wouldn't have enough time to idle down then it would burn the gas still in the cylinders. Like 65hoss said, let it idle. I'd imagine that if you put it into gear right before you turned it off it might not backfire because of the RPMs being lowered. Same way how to stop a car that diesels after turning it off.

01-27-2004, 01:54 PM
What he is experiencing is a characteristic of kawi's. Kinda like the kohlers have their own characteristics of backfiring on shutdown.