9 Most Common John Deere z915e Problems & Solutions

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By Marvin Tucker

Farming Equipment

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The z915e or the ‘ZTrack’ series of mowers is John Deere’s most popular line of zero–turn mowers. It’s a commercial-grade machine capable of handling the most demanding mowing jobs. It boasts a monstrous 25hp engine that will make short work of large plots of land.

Despite being a lower model within the ZTrak series, it’s still one of the most popular choices for buyers looking for the best value for the hard-earned money.

However, many users have reported running into issues with the machine that you should be aware of before making such a heavy investment. So in this article, we’ll cover what those problems are and how to go about fixing them.

The most common problems with the John Deere z915e

Many models with the John Deere ZTrak range are similar, featuring the same hydrostatic drive chain and a commercial-grade deluxe comfort seat. Of course, the very popular 7-Iron II Mowing Deck can maneuver through the tightest spots thanks to its zero-turn functionality.

Compared to higher-end models such as the 950 and 960, it has a slightly smaller mower deck size and less powerful engine but is identical in almost every other way. 

While John Deere is well known for its exceptional build quality feature-complete mowers, there are quite a few problems that can crop up with this machine that you should know how to deal with to keep it in good working order.

1. The engine doesn’t start

A common complaint among users is that the John Deere zero-turn mower doesn’t start. And while there is a multitude of potential reasons why this might occur, they are all relatively easy to troubleshoot.

  • First, you should check that there is enough fuel in the tank. If there is not enough fuel, then the engine will not be able to run, so top it off with new, high-quality fuel.
  • Fuel can degrade over time, so if the mower has been left idle for a long time, it’s often a good idea to discard the old fuel and re-fill it up with new, fresh fuel.
  • If you live in a colder climate, moisture can make its way into the engine through condensation, interfering with the engine’s combustion process. Here an oil change might help get the engine started. Once it’s running, let it warm up for a good 5 minutes idle before putting it under load.
  • Next, you should check the fuel filter, which is designed to remove any debris from the fuel before it can make its way into the engine and cause damage. Remove the filter and clean it. If the filter looks old, you can replace it.

2. Problems with the steering

One of the most significant benefits of the zero-turn system is that you can use it to maneuver around tight and awkward spots. So if you start having problems with your steering, it will hamper your ability to move around correctly.

A big contributor to steering problems is uneven tire pressure which causes the mower decks to lean down on one side and the steering gear to slip. Ensure that all tires are inflated with the same amount of pressure.

Over time, wheel bearings might also become worn or broken, making them difficult to control. These should be checked, and if any of them are defective, replace them.

Finally, you should be mindful of where you are driving. Uneven terrain or areas with a lot of rocks and sticks can cause movement difficulty, so don’t be afraid to clear the ground a bit by hand before trying to mow over it.

3. Hydraulic pump problems

The x915e’s hydraulic system is an intrinsic part of controlling the  John Deere zero-turn mower deck and setting the cutting height. So when this runs into problems, it will very quickly compromise your ability to mow well, particularly over uneven terrain.

Air that’s made its way into the system significantly contributes to hydraulic pump problems. This could be through a breach in the system somewhere, such as a loose connection or a leak.

Once the air is in the system, it will reduce the pump’s ability to generate pressure. So the solution here is first to identify where the breach has occurred and seal it.

After you have sealed the breach, you should bleed the hydraulic system to remove the air.

Also, remember that foreign particulate can enter the hydraulic system through these breaches. Hence, it’s often a good idea to exchange the old hydraulic oil for fresh, new oil to ensure the system is as smooth as possible. 

4. Smoke is produced on startup

Upon starting the engine, you notice a lot of blue/white smoke being produced, which is usually an indication that an excess of fuel is burnt off.

This is not an issue with an excess of fuel but rather a lack of air, causing the additional fuel to burn off. We call an engine being hit with too much fuel ‘running rich.’

To fix this, we have to check the air intake filter, which is responsible for filtering out debris from entering the engine. Over time this can become blocked, preventing enough air from making its way into the engine, thus making it run rich.

The solution is to clear out the air filter so air can be taken into the engine unimpeded.

You may also need to double-check that the carburetor is set correctly and produces the proper fuel-to-air ratio.

5. The spark plug isn’t working

The spark plug is responsible for generating a small electrical charge which ignites the fuel and beings the engine combustion process. 

It’s a common failure component and will often have to be replaced. But before you do that, check that it hasn’t become dirty or corroded, causing the engine to misfire.

Remove the spark plug, clean it, check the gap, and ensure it’s set according to the x915e specification.

If it all looks okay and the engine isn’t starting, replace it with a new one.

6. Blocked fuel system

A blockage in the fuel system can cause the lawn mower to run poorly due to the engine not being adequately supplied with fuel.

In this situation, the fuel filter should filter out all the contaminants. However, the fuel system may still become plugged up if it’s already old or worn.

First, you should change the fuel filter to a new one. Then flush the fuel system to remove all the old contaminants and fill it with fresh, new fuel.

7. Poor cut quality

After prolonged use, you may find that the cut quality of the z915e starts to degrade. This is pretty common and is usually caused by the lawn tractor blade becoming dull.

John Deere recommends re-sharpening the blades about every 25 hours of continuous use. However, after inspecting the blades, if you notice that they are bent or significant ‘chunks’ taken out of the material due to collisions with rocks and other debris, the blade should be replaced with new ones.

In addition, you should also ensure that all the tires have equal pressure in them, as if one is slightly deflated, it will cause the lawn tractor to lean down unevenly on that side, resulting in an uneven cut.

8. The battery won’t charge

Over time, batteries will naturally dissipate their charge, so if you’ve had the mower in storage for a prolonged period, be sure to recharge the battery before you try to use it.

However, if you notice that even after charging, it seems to run empty unusually quickly, it may indicate that the cells within the battery are dying and it will no longer hold a charge.

Unfortunately, the only solution here is to replace the battery with a new one.

But before you do that, you should also check the terminals to see if any connections have become loose or corroded. If you see apparent wear and corrosion, you can clean these off with a baking soda cleaning mix consisting of 2 cups of water and three heaped tablespoons of baking soda.

Using this mix scrub the terminals with a wire brush to clean them off.

9. The mower backfires

If you are finding that your mower backfires, the first thing you should be mindful of is how you use the engine, as one of the most common causes of backfiring is decelerating the engine too quickly.

If you are confident you have this in order, you should check that you are using the correct type of gasoline for what the mower is designed for, as using the whole fuel type can also cause this.

Finally, you should check the carburetor and spark plug to ensure they are both set up and working correctly.

John Deere z915e Problems: Are they a deal-breaker?

The x915e boasts a load of features and a potent engine for its price point. However, as with most of the bigger and more part-complete tractors, it does come with many problems you will need to contend with to keep everything running smoothly.

If this particular model is at the top of your intended budget, then we think this is one of the best machines. However, if you have the budget available, you may find one of the higher-end john deere ztrak models, such as the z930 or 960, to be slightly more robust and reliable.

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