10 Issues That Plaque the Gravely ZT HD Zero Turn Mower and Some Quick and Easy Solutions

The Gravely ZT HD Zero Turn Mower is the top-selling machine in its class, but that’s not to say issues don’t come up now and again. We’ve compiled a list of the 10 most common issues that plague the Gravely ZT HD Zero Turn Mower. We’ve also included some troubleshooting tips and solutions that you can work through whenever problems arise.

Motor Doesn’t Start

The only thing worse than a mower that stops working in the middle of a mowing job is a mower that won’t start at all. Here are a few things that could be stopping your machine from starting:

Fuel Issues

Check to make sure that your mower’s fuel tank has plenty of gas. Take care to remove any fuel left over from a previous year’s mowing season. Gasoline tends to lose its potency over time. Moreover, older fuel is more susceptible to contamination.

Check to see if the fuel level is going down at a rate that is not consistent with your usage. There’s a good chance a leaky fuel tank is leaving you with an inadequate amount of gas. Signs of a fuel leak include burnt patches of grass, a strong fuel odor, and unexplained fuel loss.

Carefully examine your mower’s fuel tank and all of its accessory components. Gas may be leaking from the tank, line, pump, carburetor, valve, gasket, or cap. The issue may also be related to a stuck float needle, a faulty fuel shut-off valve, or a malfunctioning fuel pump. `

You’ll need to thoroughly inspect and test each part so that you can pinpoint the specific issue plaguing your machine. Stay the course, and try not to get frustrated. There are several parts to a mower’s fuel system. Each piece will need to be inspected before it can be dismissed from your consideration.

Faulty Battery or Battery Connection

A Gravely ZT HD Zero Turn Mower will cease to start when there is a poor connection between the battery and the battery cable. If a quick tightening job doesn’t resolve the issue, you’ll have to consider the possibility that you’re issue is a dead battery.

While Gravely mowers can be jump-started, the manufacturer strongly suggests against this practice. A replacement battery should be relatively inexpensive and a much safer option. According to the experts, most Gravely parts are good for 2,000 hours of use. After that dead batteries and other small issues are not uncommon.

Bad Fuel Cap

A non-venting fuel cap may be disrupting your mower’s fuel flow and keeping it from starting. Remove the fuel cap. Then start your mower. If the machine starts, then it’s most likely that the fuel cap is causing some sort of blockage. Use a wire brush to remove debris from the gas cap’s vent.

Plugged Air Filter

If your engine is starting rough or not starting at all, it may be a sign that you need to replace your mower’s air filter. An overly soiled air filter may be keeping your engine from turning over smoothly. Keep in mind that merely removing an air filter is never an option. Air filters keep harmful dirt and debris from entering a mower’s engine.

According to Gravely, a lawn mower’s air cap should be replaced after 50 hours or approximately one year of usage. When you’re replacing the air filter, be sure to wipe down the housing that surrounds the filter. Remove dirt and debris to be sure that they do not enter the machine’s air intake valve.

Issues Within the Fuel Line

A clogged or damaged fuel line may be keeping your mower from getting the fuel it needs to start. Inspect the fuel line, fuel pump, and fuel filter for defects and blockages.

Dirty Carburetor

Lawnmower carburetors typically become dirty with use. Over time, this may prevent a mower from being able to properly regulate fuel. Disconnect your mower’s carburetor. Use carburetor cleaner to remove stubborn gunk. There are plenty of online resources on how to remove, clean, and replace Gravely carburetors.

Faulty Spark Plug

A faulty spark plug may be the thing keeping you from your landscaping duties. Use your user’s manual to locate and identify your mower’s spark plug. Visually inspect the component. Look for obvious defects and signs of wear. Use a stiff wire brush to remove any noticeable buildup from the outside of the spark plug. If the spark plug is exceptionally worn, you’ll want to replace it. You’ll also want to inspect the spark plug connection before you continue to troubleshoot your engine’s issues.

Motor Smokes

A smoking lawn mower is an alarming sight. It’s also an obvious sign that a mower should be powered down. In the case of a smoking mower, you must rule out any minor issues before moving on to the big ones. Keep a close eye on the color of the smoke, as it may help you to better identify the source of the issue.

Your engine may also be smoking because there is too much or too little oil in the fuel. Be sure to make time for regular oil changes. Check out this video to see how a Gravely mower’s oil is changed.

Another common cause of engine smoke is an overly rich fuel mixture. When this is the issue plaguing a machine, the smoke in question is usually dark black. Keep in mind that your engine may be also running rich because one of the mower’s piston rings is worn or the engine gasket is bad. Black smoke is also sometimes a sign of a clogged air filter.

Engine Running Rough

A rough-running engine can be caused by everything from a poorly positioned choke control knob to a damaged motor element. Check that your mower’s choke is positioned to the right. If it isn’t, place it in the off position. Then restart your mower’s engine. Diagnosing an engine issue is going to be much more difficult. All your engine-related issues should be delegated to a professional technician.

Many Gravely owners also complain that their mowers vibrate. A particularly bouncy mower may be the product of poor-quality mounting bolts, faulty ball bearings, or broken brackets.

If all else fails, check your air filter. A dirty or clogged air filter cartridge can cause a mower to run rough. Moreover, air filters should be replaced regularly.

Poor or Uneven Cuts

Several things could be causing your Gravely to cut poorly. First and foremost, you’ll want to check to see that there is enough air in your mower’s tires.

If the tires make it past your inspection, the issue may be more closely related to the blades themselves. Dull or bent blades will produce uneven cuts. Blades are easily damaged by rocks and roots. Check to make sure that your mower’s blades are sharp and straight. If your mower’s blades are not in good shape, you’ll want to have them sharpened or replaced. Never attempt to straighten your blades on your own. Bent or manipulated blades are extremely hazardous. They have the potential to slip off and injure nearby people and animals.

Faulty spindle bearings are another potential cause of those uneven cuts. Check out this video to see how to remove and install new spindle bearings.

You may also find that the blades are malfunctioning because there is an excessive amount of debris stuck in the mower’s cutting deck. Check out this video to see how dirty a Gravely’s deck can become after a year of service.

Blades Won’t Engage

When a Gravely ZT HD Zero Turn Mower’s blades fail to engage, it’s often a sign that something is going wrong with the machine’s belt. A busted, stretched, or loose belt will leave a lawn mower stuck in first gear. This issue could also be caused by a broken clutch, a faulty PTO switch, or a failed connection between two parts. Use a voltage meter to check if there is power on the battery side of the switch. Move the meter along the wire route to identify any potential roadblocks.

Mower is Noisy

Unwarranted mower noise is one of the most common and frustrating issues reported by Gravely mower owners. Loud screeching sounds often indicate that something is going wrong with a mower’s belt. If you replace the belt but the noises persist, you’ll want to inspect your mower’s blades and decks for defects. Clanking metal sounds typically stem from loose or damaged blades. Your mower may also be rattling because a piece is not connected. Most noise issues are easy to resolve. As always, troubleshooting takes lots of patience and ingenuity.

Mower Moves When the Engine is Off

A moving but off mower may be caused by a faulty parking brake. Parking brake issues are some of Gravely ZT HD Zero Turn Mower users most frequently experienced issues.

Engine Overheating

Gravely ZT HD Zero Turn Mowers tend to overheat when their air filters are clogged and/or their cooling fans are broken. A buildup of grass and other debris may also be keeping air from flowing through your engine’s coils. Of course, your mower may also be running hot due to a lack of adequate and clean oil.

Mower Suddenly Ceases to Move

You’re traveling along in your mower when the machine suddenly ceases to move forward or backward. A lawn mower that refuses to move is certainly problematic. The transmission belt or transaxles are likely faulty. If that’s not the case, you might have a broken spring or pulley.

Issues such as this are easy to resolve, but they require in-depth knowledge and immense attention to detail. We recommend that you call in a qualified tech. They’ll be able to save you a lot of time and stress. Contact your local Gravely dealer and schedule a time for a repair.

Mower Has No Suction

Is your mower struggling to collect leaves and grass clippings? If so, you may want to inspect each part of your mower’s mulching kit to be sure there aren’t any outlying blockages or faulty connections. When the ZT HD Zero Turn’s bagging system is working, it leaves yards completely free of debris.

If the issue persists and no clogs are found, there’s a good chance you have a malfunctioning vacuum pump or broken vacuum hose. Check to make sure that all parts of the vacuum system are properly connected and fully functional.

Final Thoughts

Don’t let this list of minor issues deter you from purchasing a Gravely Zero Turn lawn mower. This beloved tool makes an excellent addition to any arsenal of landscaping tools. Most of the issues that arise with this mower are easy to troubleshoot and resolve. You can avoid many of the mower’s most common problems by sticking to a maintenance schedule and adhering to the manufacturer’s usage guidelines. Should a problem arise, you can use this guide to pinpoint and possibly even resolve the issue.