Exmark Lazer Z - Sluggish performance

[Garlydog]

Hello everyone,
I hope this is the right place to post this thread. One of my Exmark Lazer Z mowers today has gotten really sluggish in it's performance.

It was running fine. Then I stopped for a few minutes, turning the mower off, to move some debris out of my path. When I went to start the mower, it was really hard to start, was backfiring, and running rough.

I checked the air filter, fuel filter - Seem OK, not sure how to test the fuel filter. I can blow through it...
Replaced the spark plugs. That helped some, but not nearly enough.
Hydrolic oil is full - no leaks. Oil level is OK

The engine runs OK at idle. When I go uphill with PTO on, it bogs down. Even going up hill without PTO on, it bogs down. It has lost it's giddy up.

Any suggestions for what to try next?

Thanks
Gary

 

[Lawnranger]

Many possibilities but it sounds like it may be starving for fuel. A partially clogged main jet in the carburetor can cause this condition and so can a plugged vent in the fuel tank cap. Start by loosening the fuel tank cap when the problem occurs and see if the extra venting helps. If not, you may need to look in the carburetor. Again, many possibilities but from my experience fuel related issues are the main culprit.

Some more possibilities are a restricted exhaust, parking brake hanging up, something stuck in the brake mechanism, a dry wheel bearing causing excessive drag, etc, etc, etc,.

Without us being able to see and hear the problem occur, you may just have to use the process of elimination and start with the simplest first.

 

[Garlydog]

I figured out what was wrong with the mower.

One of the lifters came loose and it's exhaust push rod got bent.

I removed and replaced both the exhaust and intake push rods, torqued them down to spec and the engine fired right up with full power. I decided to check the other side, sure enough, the lifters were coming loose on the other side as well. I torqued them down to spec as well.

My guess is vibration over time caused the lifter bolt the loosen just enough to allow the push rod to squeak free.

I will add this tightening step to my annual maintenance schedule to hopefully avoid this problem in the future.