View Full Version : Hustler Super Z Back Fire

10-18-2004, 07:56 PM
I am having problems with the engine back firing when it it shut down. It also seems like sometimes when I turn it off it sounds like it is going off then kicks back in for a second then goes off. Its either a 27 or 28hp kohler and has 55 hours on it.

Travis Followell
10-18-2004, 08:00 PM
That is absolutely normal for the kohler engines. We have 2 that do that all the time. All you would have to do to stop that is cut it off about half throttle and it wouldn't do that.

10-18-2004, 08:02 PM
Thanks that fixed the problem of it wanting to kick back in, but it still back fires. It sounds like a gun going off when I shut it down.

10-18-2004, 09:15 PM
I have a Kohler on my 44" Toro and it did the same thing. What I do now is let it cool down for a couple of minutes on low throttle while I am trimming. Never backfires after a cool down. Hope that helps.

10-18-2004, 09:32 PM
Shut the unit off at full throttle...works on all ours.

10-18-2004, 09:34 PM
Why should you have to let it cool down???? This is a problem with the 27HP Kohler on my Hustler Super Z also. I consider it a design flaw. I think it's beyond belief that a company as large as Kohler could let this be such a problem with their engines. EVERYONE knows that Kohlers have this problem. Why can't they fix the problem. I don't know about you, but I'm not wasting my time or gasoline for the thing to cool down. If it blows up let them replace it under warranty. All I know is that Kawis DON'T have this problem. It's really embarassing to to have to stop the mower to talk with a customer that comes out to ask a question about their property. I just tell them that my $8000.00 mower is suposed to go "boom" when I shut it down.

10-18-2004, 09:36 PM
I've found that reducing my throttle to its lowest level and letting it "idle" for 5-10 secs before turning it off has stopped the backfire 95%. Every once in a while it still pops. BTW its a 27Koh on a SuperZ. I too had another Koh, a 20HP on a Toro Hydrowalk that did the same thing and the "idle down" helped it too!

Metro Lawn
10-18-2004, 09:37 PM
Well, the Super Zs we have with the 25hp Kaws on them also do this... backfire at shutdown that is... no run on

10-18-2004, 11:08 PM
If you have an owners manual . READ IT. The larger HP engines all say to not cut the ignition off at less than 1/2 throttle. Kohler. Kaw, Honda. Its because of the electric fuel cut off valve in the carb. :blob3: :blob3: :blob3: :blob3:

10-19-2004, 04:08 PM
When shutting the engine off with a fuel shut off solenoid on the carb, leave the throttle WIDE OPEN.

10-19-2004, 05:11 PM
I know it's time to clean the precleaner when mine(25 hp Kohler) backfires. Otherwise, it's important to let it cool :cool2: down for a few seconds after working under load.

10-19-2004, 06:51 PM
This problem is persistant on all newer aircooled engines. My 23 kawasaki does it at all throttle positions when turning off the ignition. The problem is caused by raw fuel being drawn into the cylinders after the ignition is switched off. Once the fuel is in the cylinder it is ignited by the hot valves and piston resulting in the backfire.
The problem seems to be with the fuel not being shut off at the same time that the ignition is. I agree with Mowerman that it has to be in the design.

10-19-2004, 08:53 PM
I have a 15hp Kohler on a WB and have to throttle it down for a few seconds. The engine has about 1300hrs on it and has done this since day one. For what it's worth I have a 18hp air cooled Onan in a garden tractor and it does the same thing. That engine is a 1983 model. Matt

10-19-2004, 09:52 PM
the real reason it backfires is beacause a small lawn mower engine shuts off by cutting the power to the spark plugs. Gas continues to pour in as the engine winds down. As the gas hits the hot cylinder wall it quickly evaporates and creates high pressure, then the "bang". After a few hundred hours it will stop. Get EFI (Electronic Fuel Injection) if you don't want backfire.