7 Most Common John Deere 790 Problems & Troubleshooting

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By Marvin Tucker

Farming Equipment

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The John Deere 790 is the perfect utility tractor for those looking for a machine that can handle all their general purpose ranching and farming needs, packing just the right amount of power for a very reasonable price.

Featuring a powerful diesel engine with direct fuel injection, cast-aluminum pistons, and a high-capacity lubrication system means it will handle all but the most demanding jobs.

Not only that, but there’s a range of attachments available, and it had some of the most user-friendly operations seen in a budget-orientated tractor.

But like any tractor, it does suffer from some issues. So today, we’re going to go through them so you can get a good idea of what’s in store should you decide to buy this popular utility tractor.

The most common problems with John Deere 790

The 790 is a fantastic unit and offers a great price for performance. Its 27-gross horsepower engine makes it ideal for general jobs around the farm, and between the various attachments, there are few tasks it won’t be able to handle.

This John Deere tractor offers many user-friendly conveniences, such as seats that flip forward to protect the seating area from the elements and a roll-over/roll cage structure that protects you in the event of an accident.

But despite all the features, there are numerous issues users have reported encountering with this model. But does that make it a poor purchasing decision? Let’s take a closer look at those issues and if they are easy to solve.

1. The unit will not start

This is probably one of the most common issues that users have reported encountering on this John Deere Tractor and can, at first glance, seem like a catastrophic failure. 

However, multiple issues can potentially contribute to this problem, most of which are circumvented with general good habits and maintenance practices.

The first thing to check is the battery and to ensure it’s not drained. Then the connection points should be checked for corrosion which may affect their ability to send power to the system.

If you discover this is the case, you can often get away with using a wire brush to clean the connections and then retighten them manually – no big deal!

Another essential thing to check is whether the fuel shut-off valve is open or not. This is often engaged to stop fuel flooding the engine during transportation, but this needs to be disengaged once you’re ready to use the machine.

Check that there is adequate fuel and that it isn’t too stale. If it has become old, you may need to flush the oil fuel (it will appear murky and clumpy compared to fresh fuel) and refill it with new fuel.

Those are the main contributing factors, but there are a few other things you may want to take a look at:

  • Is it too cold? If it’s been standing out in the cold for too long, it may be too cold for the cylinder to combust and will not start.
  • Check the fuel filter and air intake filters are not plugged up.
  • Check that there is no blown fuse and replace it if there is.

2. Loader issues

If there’s one common theme among the critical users of the 790, that criticism is usually levied toward the loader. While the unit is fantastic for general tasks and light to medium lifts, that lower-powered loader can struggle with some more demanding tasks.

Unfortunately, nothing can be done on the user’s side regarding the raw power. However, people have also reported issues with maintaining the angle of the loader bucket.

If you find this is not set correctly, you will need to remove the bucket and re-attach it. For many users, it’s probably easier to have a trained mechanic do this. But if you wish to try it yourself, here’s how to do it:

  1. The first thing to do is lower the bucket to the ground. It needs to be completely touching the ground for it to be disconnected.
  2. Then disconnect the bucket.
  3. Move ever so slightly forward; this will lift pressure away from the front axle of the unit and place it onto the front end of the bucket.
  4. Next, you need to lift the knuckles into place on both sides.
  5. Lift the knuckles into the upright position and engage the lock, latching them onto the frame.
  6. Next, pull the loader slowly back and allow the front arm to fall into place. Once it is completely disconnected, it will rest on the ground.
  7. Turn on the handbrake and turn off the machine.
  8. Using the loader’s joystick, release the hydraulic pressure. IMPORTANT: make sure there is no residual pressure in the hydraulic lines before disconnecting.
  9. Remove all the hydraulic lines and place dust caps on them.

Now the old bucket is removed, here’s how to install the new one:

  1. Once the new one is ready to install, remove the dust caps we placed on the hydraulic lines and make sure they are free of dust and debris.
  2. Pull the loader forward into position over the bucket.
  3. Lower both knuckles into place.
  4. Slowly lift the bucket back up.

3. Electrical issues

It’s been reported that minor electrical issues can fairly consistently crop up with the 790 compact utility tractor. This includes things like bad switches or defective parts.

While these are certainly not catastrophic failures and something anyone with some basic electrical knowledge will be able to fix. It is a hassle many busy people don’t want to be dealing with.

The best way to circumvent these minor issues is to give the unit a monthly service. This ensures that any components on their way out can be replaced quickly rather than having them fail at an inconvenient moment.

4. Problems with fuel flow

One issue that may crop up is that the engine cannot get an adequate flow of oil, resulting in low power on the compact utility tractor.

The common cause of this is the engine being shut off, which causes debris to be pulled across the oil filter, which needs to be cleaned.

In addition, there’s also the possibility of a small breach in the fuel line, which allows air to get pulled in as the vacuum increases. 

The injector and lift pump should be checked. The lines running to the filter will also need to be checked by passing air through them and checking for breaches in the line.

If you cannot discover and plug the breach yourself, it may be simpler to pay a visit to the dealer.

5. Underperforming system

Of course, it can be pretty alarming when the system starts to underperform, and loads that were previously handled easily are suddenly a struggle.

If this is happening to you, the most likely cause is due to insufficient hydraulic fluid. You will have to check the reservoir and ensure it’s adequately topped up, and you should find that the 790’s back to her old self again.

6. Unexpected stalling

In addition to the unit just not starting. One problem users commonly report is that it will suddenly stall for no reason.

The most common cause of this is due to a clogged valve or issue relating to the fuel filters.

The solution here is to give the entire fuel system a solid check. The valves and filters may need cleaning and maintenance to prevent this issue.

7. Leaky fittings

Unfortunately, over time the 790 is quite prone to developing leaky fittings. While once again, it’s not catastrophic, these can lead to awkward delays in your busy schedule as you try to diagnose and fix these issues.

The primary solution here is to keep up with the general maintenance of the machine, mainly if yours is already a few years old or was purchased from the used market.

At least once a month, try to inspect the machine thoroughly for any leaks and address them sooner rather than later. As with many tractor issues, prevention is usually the best solution.

John Deere 790 problems: Are they a deal-breaker?

While almost all of these issues you will encounter with the 790 are things you will find on other tractors, whether they will be a deal breaker or not comes down to your intended use of the machine.

This is designed for general use. The lower-powered engine and plethora of available attachments mean it’s intended as a general-use runaround machine.

If that is your intended use for the machine and you plan to keep up with the general maintenance, then this will serve you well and not break the bank.

However, suppose you need it to perform even a few more heavy/demanding tasks. In that case, this is probably not ideal, and it will end up causing additional strain on the machine, which can lead to many of the issues we have covered here today.

If this is your intended use, we recommend looking for something more robust.

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