Engine Lazer Z HP dropping RPMs for no reason

[Bkanneg]

I have an older Exmark Lazer Z HP that seems to be losing RPMs for no reason. It is from about 2001 - 2002 timeframe. The Engine is a 21hp kawasaki.

It will seem to be running just fine, then all of a sudden, the engine will sound like it is bogging down and the blades will start losing a bunch of rpms. This happens whether I'm going thru grass or not. It will sometimes do it whether the blades are engaged or not.

After a while of this, it will just pop back to full RPM and seem to run fine for a while, then it will do it again for no reason.

Could this be a fuel pump or fuel filter issue? I had it to the shop, but of course it wouldn't do it while they had it.

I appreciate any suggestions you can give.

 

[chance123]

Twenty ONE HP? Are you sure of that HP? Most of those machines have the FD 750-D which is a 27 HP water pumper. What Kawai engine do you have?

 

[Bkanneg]

Sure of it. It is an FH641V model.

 

[Exmark fan]

Sounds like a coil is going bad. Starting to break down.

 

[Bkanneg]

Should an exmark repair place be able to fix that? What kind of cost am I looking at if it is a bad coil? Anything they can do to test the coil out? As I said, it didn't happen the last time I took it in to them.

 

[Exmark fan]

If they have a good service department. They should be able to fix it. Coils are anywhere from $50 to $100 plus the labor to fix. Usually the start breaking down. Not doing it all the time. But as time goes by. It will go out