Zero turn low RPM issue

[grayhame]

I have an older Dixon ZTR that has started acting oddly. It will run normally and occasionally while using it, it sounds like the RPM's decrease and I have to slow down to a crawl to so that the blades came keep up. Accelerating the mower can cause the engine to stop. While it's happening, I can smell a strong fuel smell coming from the exhaust.

 

[Born2Mow]

Welcome !

My first thought is that your belts are slipping, and that smell is from very hot belts... not the exhaust. The belts can feel "tight" to the 'pull test' and you might suppose that is enough. But belts also need to be soft in order to grip the sheaves. As belts age, they also harden. You may see other signs of belt hardening in the form of small cracks in the rubber, but only on the narrower inside part of the belt.

On the other hand, if you just installed new belts quite often 3rd party belts hardly ever match the correct length. Standard belts come in whole inch increments (eg 36.0"), whereas the factory mower belt might call for 35.4". The issue with slipping could be the excess length.

Hope this helps.

 

[ILENGINE]

I am leanng toward a twin cylinder dropping a cylinder due to some mechanical or ignition issue.

 

[grayhame]

Thanks for the suggestions! I did some troubleshooting by unplugging the sparkplug while it was idling low. Unplugged one side and it died. Started it back up and unplugged the other side and it kept running and running low. Based on some googling that sounds like a cylinder dropping. Since it doesn't run low all the time, is the problem outside of the cylinder in the wiring or spark? What can I look at next?

 

[Born2Mow]

Several things could cause that. All related to "tuning issues"...

• Old fuel. Is this fuel left over from last year ? That's the No.1 no-no.
• Carb needs idle mixture adjustments, or "idle circuit" inside carb is
• Old spark plug, plug fouling, plug burned to wide spark gap, other plug issues.
• Valve adjustment way out
• Low compression on one cylinder
• Water in the carb from recent washing. Check the float bowl.

30 minutes of general "attention" could go a long way.