4 Most Common Problems with John Deere 790 and Their Fixes

The John Deere 790 tractor has the Yanmar 3TNE84 diesel 3-cylinder liquid-cooled 91.3 ci [1.5 L] engine, unsynchronized transmission system, 8 forward and 2 reverse gearbox system, a category 1 three-point hitch and its pto is rated at 24 hp. This John Deere tractor has manual or power steering and is offered in 2WD and 4WD. 

However, among these great features, the customers sometime face some issues like fuel problems, front end issue, starting issues, and others. So, today I have discussed the possible john deere790 problems with the solutions.

Common Problems with John Deere 790 and Their Solutions:

Check out these john deere790 problems and solutions in details below:

1. Starting Issue

A buyer shared his starting problem with JD 790. This can happen for the wrong position in the transmission gearshift lever. You need to place the range shift lever to neutral. Again, the engine throttle lever may not be pushed forward. Move throttle to half throttle.

Sometimes, the battery connection is loose or corroded. Use a wire brush to clean the connections and retighten.

Check whether the fuel shutoff valve is open or not.

Tale fuel/improper fuel level can also be the reason. Drain fuel and refill with new fuel to capacity.

To know the level, open the gas cap and waft toward the nose, if the smell is stale or sour it needs to be flushed. Take note of the look of the stale fuel as you empty, it isn’t as clear as proper fuel and often includes clumps.

Wrong engine oil viscosity, plugged fuel filter, plugged air intake filter, blown fuse – these are also some reasons. 

Measure the fuse on a non-conducting surface (i.e. wood or plastic), if the reading is similar to the multimeter test reading the fuse is good, If it doesn’t change from the starting reading it needs to be replaced.

Additionally, if your tractor cranks, but won’t start, you’ll want to look at a few different engine components.  

  • Is the fuel making it to the cylinder? 
  •  Is it too cold for the cylinder to combust the air/fuel mixture?

2. Front-end issue

A maximum of the users have problems with the front-end loader. This compact tractor has an under-engineered front-end drive on the wheels. It needs a beefier setup.

To remove and install the Front End Loader, you need to follow some steps – 

1) Lower the Bucket Until it Rests on the Ground. Disconnect the bucket. There should not be any space between the ground and the bucket to avoid excess movement.

2) Move Slightly Forward to put forward pressure onto the arms and bucket of the implement while relieving pressure off of the front axle.

3) Lift the Knuckles Into Place on Both Sides. While lifting the knuckles into the upright position, they will engage the lock and latches them to the frame of the implement.

4) Begin to Pull Away From the End Loader. Using the loader joystick, pull back slowly and allow the front arm to drop into place. Once the loader is fully disconnected, it will fall back into place and rest on the ground.

5) Engage the Parking Brake, Turn Off & Step Off the Machine

6) Use the Loader Joystick to Release Hydraulic Pressure & Carefully Disconnect Hydraulic Lines.

There may still be excess pressure remaining in the hydraulic lines, be very careful during the removal process even after wiggling the joystick.

7) Place Dust Caps on Hydraulic Lines.

Depending on the length of time between connections; dirt, water, dust, and other debris can build up in the lines and cause damage or disruption when connecting. To assure a quick and easy connection process, be sure to place the caps on when storing the front loader. 

Installing the Front Loader

You’ve done all the work when removing the Front Loader, so the reattachment process of the new one should be a quick and easy process that gets you right back to work.

  • Remove Dust Caps, Check Lines for Debris & Reconnect Hydraulics
  • Using the Loader Joystick, Pull Forward Into the Implement
  • Lower Knuckles on Both Sides into Place 
  • Slowly Lift Bucket Into Place

3. Fuel issue

Sometimes the engine doesn’t get the proper flow of oil. The strainer gets plugged up. When the engine shuts down the debris falls off until it gets sucked across the strainer again.

Another possibility is a small pin hole in a fuel line that lets air get sucked in when the vacuum is high enough. The injector pump and the lift pump to supply the injector pump – should be checked. The 790 has the tank on top. So, empty it, take it off, and make absolutely sure there was no debris in it. Then clean the strainer, disconnect the lines to the filter and blow compressed air through them.

Plug that line and pull a vacuum to see if it held. If not, there’s a pinhole in the line. Follow a similar process from the tank to the injector pump to make sure it’s all good to that pump. If that doesn’t fix the issue you could have an injector pump issue at which point some specialized tools are required just to test it. Probably would mean a visit to the dealer.

4. Drive belt issues

A customer complained about the drive belt issue. The tractor didn’t move forward or reverse and smelt like the belt was heating up.

To solve this issue, you need to replace the belt –

  • Disconnect the spark plug – Lift the mower hood and disconnect the spark plug wire.
  • Remove the 
  • deck – Disengage the cutting blades, disconnect the right suspension arm and right rear deck bracket. Pull out the deck from under the frame. 
  • Detaching the ground drive belt – Remove the engine pulley bolt and then pull the engine pulley off the crankshaft. Release the drive belt from the idler pulleys and belt guides. 
  • Lifting the battery: Release the bolts that connect the cables to the batteries. And put the battery out of the battery box.
  • Removing the ground drive belt: Release the drive belt from the transaxle pulley and pull out the ground drive belt. 
  • Install the new ground drive belt: Loop the belt over the transaxle pulley, position all the bolts, connect all the cables, and install the engine pulley bolt and washer.
  • Reinstall the deck – Push the deck near and under the tractor frame. Reconnect all the connections, right suspension arm, and deck bracket. Check the belt moving on the mower deck, and adjust everything. And then, reconnect the spark plug wire and lower the tractor hood. 

Go through the manual to see how to remove the cutting deck and then the belt. You can also ask the help of an assistant to do things faster.

Other Parts Problems:

Some have encountered no-start issues.

It can happen for the starving for the required fuel flow in the system. That’s why the engine will fail to start.

To figure out the issue, check the fuel tank, filter, electric fuel pump, and injector. 

Replace the damaged or clogged part that causes the fuel to run accurately and let the engine correctly.

You need to check the oil viscosity as well. 

What Majority of the Users Feel About John Deere 790?

The customers say that it runs very smoothly and is very economical on diesel. They can mow for 5 to 6 hours on 3 to 4 gallons with this super little machine. This small and narrow one is suitable for tight places.

 This is suitable for homeowners with 1-10 Acres with a short wheelbase.

However, there is no backhoe and has an under-engineered front end, also bucket sags while operating.

So, you can go for this one if you are looking for a budget-friendly tractor for your small space.

Final Words 

Now that you know the John Deere 790 problems, you will easily be able to fix them. But remember, every component of a tractor needs regular maintenance to provide high efficiency.

So, follow the steps of troubleshooting and let me know the results.

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