No power/boggs down

Todd J

Member
Messages
16
I have a 54" Magnum Bad Boy Mower with the 27 hp Briggs and Stratton engine. This thing has been a problem since day one. Now once again it stalls when mowing. Even if grass is only a couple of inches tall it will bog down and stop. It will barely cut at half speed. It acts as if only running on 1 cylinder. Engine has 250 hrs. I change oil, oil filter and air filter yearly. any ideas? I actually looking into swapping out engine to a Kawasaki.

Thanks for your help
Todd
 

MowLife

Well-Known Member
Messages
365
Have you confirmed both cylinders are working? Is there a differences in the spark plugs?
 

Todd J

Member
Messages
16
Both plugs look the same. Replaced them a month ago. Pulled and checked and they seem fine.
 

Todd J

Member
Messages
16
yes they were both firing. I didn't check today when I went to use it because once it started it's crap again, I put it up and used my neighbors. I'll check it tomorrow.
 

Luffydog

Well-Known Member
Messages
537
Check the fuel lines they have plastic in them that will break down and poor fuel
Flow and also check the evap lines of it has them found them
Zipped tied to the frame and will not have enough air flow to breath in the tank causing little to no fuel
Flow.
 

Todd J

Member
Messages
16
Checked compression----90# on both cylinders
Checked spark----- good spark on left cylinder....NO spark on right cylinder
I calling left and right as you sit on mower. Not sure if it's #1 or #2 cylinder.
Now what??? Coil? Could flywheel key be sheared enough to cause this?
Thanks for your help
 

ILENGINE

Lawn Pro
Messages
6,246
Sheared flywheel key won't effect spark on electronic modules. Also if you are looking at the flywheel, the cylinder closest to the flywheel is #1 which I believe would be the right cylinder in our example. Unplug the kill wire to that module and see if you have spark. No spark, bad module.
 

Todd J

Member
Messages
16
OK I'll admit it. I'm dumb. Where is this kill switch wire located? I see a module on left side of engine with 2 yellow and 1 red wire but no module on right side unless I'm blind also.
Thanks for helping the lawn mower challenged people
 

ILENGINE

Lawn Pro
Messages
6,246
Sounds like you are describing the voltage regulator wires. the module I am talking about is under the blower housing mounted on top of the cylinder and has the spark plug wire attached to it. there should be a single wire that goes to each of the two ignition modules. Unplug the wire and see if you have spark.
 

Todd J

Member
Messages
16
NO SPARK.... Must be a bad module, correct? I'll order a new one.
And the plot thickens... There is a black wire running from the blade engage switch to this plug wire. The wire is cut off on the end and it wrapped 6-8 times around plug wire and held with a zip tie??? Is this needed and if so where does it go? I don't see the other end where it would attach and why multiple wraps held by zip tie? Is this maybe for another engine that would/could be installed and that wire would then be needed?
I've had it worked on in the past while under warranty and it appears nothing was done with this wire so maybe it's not needed in my application.
Thanks
 
Last edited:

ILENGINE

Lawn Pro
Messages
6,246
Kill wire disconnected and cranking with a known good plug with no fire means bad module in most cases. When you remove the module make sure the mounting surface on the engine and module are clean and not covered in rust because that can cause issues some times.

I would say if that wire is not connected I wouldn't worry about it.
 

bertsmobile1

Lawn Royalty
Messages
12,849
The wire from the PTO switch to the module will be a safety switch.
Some 1/2 wit cut it off in order to prove evolution can go two ways and we can de-evolve back to apes.
 

Todd J

Member
Messages
16
So the saga continues. I changed the ignition module and I now have spark to that plug. Put on new fuel lines, replaced a hose with hole in it off of air cleaner housing and put everything back together. It fired right up...off to cut grass. Within 5 minutes of cutting I could sense it's still not right. It still wants to and does blog down with blades engaged cutting at any speed. It will cut at 1/4 to 1/2 speed but you can tell it's having problems. At full speed the blades almost stop and mower has trouble moving forward. Dis-engage blades and it runs fine at full speed. You can even hear a difference in engine sound. Sounds normal. With deck up and blades engaged it still blogs down (not cutting grass but blades spinning). It also started back firing and popping after about 20 minutes while blades engaged. No blade spinning no back fire. The only other thing is I have to hold back on left handle to keep it straight. Pushing them both forward causes it turn go right slightly. I just need to adjust handles to correct but if I can't use it what's the point?

Thanks for all your help. I'm to the point of draining the oil, run it till it locks up and replace engine. At least then I'll know what's wrong.
 

Luffydog

Well-Known Member
Messages
537
Check the evap lines make they are not bent to sharp. If that didn't do it would say replace the carb. Have you ran it until it starts and loosen the cap.
 

bertsmobile1

Lawn Royalty
Messages
12,849
Running on one cylinder.
Some of the V twins have a diode in the kill wire that goes from one coil to the other one.
This is to stop the coils interfearing with each other.
When this diode goes bad you get very erratic firing from one cylinder.
Pull both of the wires off & see if it goes away.
 

Todd J

Member
Messages
16
I'm still fighting this mower and it's winning. I have fire to both cylinders. When it starts now it is revved up. It slows down when throttle is pulled back but not like it should. At cutting speed is has to be over 3600 rpm from the way it sounds and it is putting out black smoke on the cylinder to the left standing at back of mower. Running rich for sure.

Now what??? I know it can be repaired just not sure what is next. Carb? Adjust valves? Blow a hole in the side of it with a .357 Magnum?

Thanks for your help
 
Top