The John Deere F725 is among the most popular front-mount lawnmowers. It’s powerful yet easy to handle. Moreover, it’s tough, enables quick deck height adjustment, and provides a clean cut.
Unfortunately, a few people report various issues with the f725. So, we’ve rounded up some of the most common John Deere f725 problems and solutions to give you a headstart.
What’s the John Deere f725?
The John Deere f725 is a front-mount riding lawnmower powered by a 20hp two-cylinder Kawasaki motor engine.
In addition, the liquid-cooled vertical shaft mower is defined by the following features;
John Deere f725 Specs
- Model: F725
- Engine: 20 hp Kawasaki gasoline-powered
- Transmission type: Belt-driven hydrostatic
- Wheelbase: 39.4 inches
- Ground clearance: 5.0 inches
- Displacement: 585 cc
- Starter: Electric
- Oil capacity: 3.8L
- Chassis: 4×2 (2WD)
7 John Deere f725 Problems
Problem #1: John Deere f725 Engine Issues
Engine issues are among the most commonly reported John Deere f725 issues. Below are the top engine issues and fixes.
Engine cycles down
If the engine cycles down in the middle of mowing, it’s most likely an electrical issue. Either a plug has failed, or a few wires are loose.
Clean the spark plug and see if the problem goes away. If it doesn’t, probe the electrical system for loose or broken wiring connections.
Then test the truck to see if the problem is gone. If it isn’t, replace the spark plug.
The engine stalls
A stalling f725 engine is often a sign that one of the cylinders is dead. If the running cylinder is not firing, raw gas gets through unburned, and the engine produces no power.
Fortunately, the f725 is a two-cylinder engine. So, you can fall back on the second cylinder if the first one fails.
Better still, you can always run the tractor on both cylinders, so it doesn’t stall if one cylinder fails.
The engine backfires
Finally, f725 backfiring can happen for many reasons. For instance, did you decelerate the engine too quickly?
If so, you may need to check your deceleration speeds next time. Alternatively, the engine may backfire if you use the wrong fuel type.
Or maybe it’s the right type but contaminated – maybe it’s been lying idle too long. In this case, cleaning the tank and replacing the old fuel fixes the problem.
Finally, inspect the spark plug and flywheel. For instance, a spark plug running too neat or too rich can cause backfiring.
Similarly, a sheared flywheel can cause the tractor to backfire. Repair or replace them appropriately.
Problem #2: The John Deere f725 Mower Doesn’t Start
Unfortunately, an f725 that won’t start can be a complex problem to diagnose. At the same time, you’ll be surprised that some causes are right on the nose.
The mower is not getting gas
The first thing to do if you’re mower refuses to start is check whether you have gas.
More importantly, check whether there’s sufficient gas and if it’s the right quality, as contaminated or old fuel can cause starting problems.
Then visit the fuel pump to get more fuel or replace the bad fuel. Additionally, determine whether the engine gets sufficient flowing fuel.
This often requires inspecting the fuel lines for leaks or obstructions. Fix both issues to ensure adequate fuel flow.
A clogged vent in the cap
Fuel flow is obstructed if one of the fuel caps is clogged. So, the mower tractor won’t start. The easiest fix is to loosen the fuel cap and check if doing so solves the problem.
If it doesn’t, remove the fuel line and crank the engine to find out whether the line flows fuel. If the fuel flows, you need a carb rebuild.
Cam and gear issues
Finally, start failures on the f725 sometimes emanate from motor issues. The tractor uses plastic cam gear that can break under stress and won’t start if the cam gear breaks.
First, you need to confirm the problem. So, remove the valve covers and observe the valves when you crank the engine.
Do they move? If so, you have a bad cam. Replace it with steel gear and, while at it, replace the oil pump gear and water pump too.
Problem #3: John Deere f725 Blowout Problems
John Deere f725 blowouts are a familiar issue among users. Below are the common causes and fixes;
Incorrect deck pitch
An incorrect deck pitch can cause blades to hit each other, resulting in a blowout. For instance, running a negative pitch is asking for trouble.
Fortunately, this is an easily fixable problem. Get off the tractor and set the distance between the blades to ⅛ to ¼.
More importantly, don’t rely on the deck edges to determine the pitch. Instead, turn the blades back-to-front and physically measure the tips.
You’re using the wrong blades
Incorrect blades can also cause blowouts. So, check whether you’re using the right blades.
Additionally, blowouts are common when using double-blade combos. Therefore, it helps to stay away from double-blade combos until you fix the blowout issues.
Problem #4: The John Deere f725 Mower Deck Keeps Falling Off
A loose mower deck that keeps falling off is often due to loose bolts, a damaged belt, or loose blades.
The deck belt is loose
A loose deck belt is the most common cause of falling decks. The solution is to find out why the belt is loose and fix the problem.
For instance, are the bolts loose? If so, tighten the nuts or replace worn nuts. Also, check the deck pitch and set it appropriately.
The deck belt is damaged
A worn or damaged belt may struggle to keep up. The best solution is to replace it. However, repairing it is a good alternative if you can find a good mechanic. Avoid DIYs for deck belt repairs.
The blades are improperly aligned
Finally, poorly aligned blades can result in uneven weight distribution, causing the mower deck to fall off. Similarly, many users report that the deck often falls when the blades fall.
Two fixes can help prevent these issues. First, align the blades correctly for even weight distribution.
In addition, tighten the blades, so they don’t unnecessarily come off. Again, replace worn bolts if necessary.
Problem #5: John Deere f725 Blade Issues
Many f725 users report that the blade dies when you engage the blade. The following are common causes of this problem and how to fix them;
A blade obstruction
Cords and pebbles are common obstructions that may prevent the blade from tuning. An easy fix is to inspect the blade, identify potential issues, and remove the obstruction.
Of course, regular maintenance can prevent this issue.
Loose connection in the seat safety feature
A loose connection in the seat safety feature can cause the engine to go off if you engage the blade. Reconnect or tape the loose fitting, and the issue disappears.
A bad clutch bearing
Finally, engaging the blade may result in engine shutdown if one of the clutch bearings is bad. Unfortunately, this problem is more challenging to diagnose and fix.
First, remove the belt and attempt to turn the clutch pulley. Does it turn freely? If it’s hard or rough, replace the clutch bearing immediately before it damages the clutch. If the clutch is damaged, replace it.
Problem #6: The John Deere f725 The Mower Keeps Going Off
Many users report that sometimes the mower starts fine, runs for about 30 minutes, then goes off, and the problem repeats if you restart the mower.
This problem is often the result of “vapor locking,” fuel line blockages, or grass buildup.
The machine is “vapor locking”
A “vapor lock” occurs when liquid fuel vaporizes, creating a lean condition (lack of sufficient liquid fuel). It often results from overheating. However, it may also occur due to compromised ventilation.
A quick way to temporarily resolve the problem is unplugging the vent hose or loosening the fuel cap when mowing.
The increased ventilation will temporarily prevent vapor locking until you can fix the problem.
Fuel line blockage
Partial fuel system blockages cause fuel shortages in the engine, often causing temporary “shutdowns.”
Probe the fuel pipes for buildup and remove blockages to fix the problem. Also, change the fuel filter.
A filthy engine surface can also cause sudden engine stops. For instance, a layer of grass clippings blocking air intake is as bad as a blocked vent hose.
So, regularly clean the machine’s interface to prevent buildup. Here’s more on why John Deere Tractor keeps shutting off.
Problems #7: The John Deere f725 Mower Smokes Excessively
All lawnmowers smoke to get rid of carbon dioxide and other combustion waste products. However, excessive smoking is often a sign of trouble.
Is it an engine problem?
Using bad or the wrong fuel can cause strange smoking issues. Similarly, a filthy tank system may cause thicker exhaust fumes. Other issues to diagnose are a bad engine and overfilled fuel tank.
Air intake issues
Air filters are responsible for eliminating dirt and contaminants from the air entering the engine’s combustion system to ensure a clean, healthy combustion process.
Otherwise, airborne contaminants can cause excessive combustion waste. Clean or replace filthy filters to prevent issues.
A dirty combustion system causes the same problems as a dirty filter. It introduces impurities to the combustion process, causing excessive smoking.
Damaged spark plugs and wires can cause similar issues. Clean or replace the plug and fix combustion wiring system issues to prevent further trouble.
Dirty or bad oil
Finally, smoking issues may also be a sign of poor engine oil. Perhaps the oil is stale, or maybe it’s too old. Fortunately, cleaning the tank and replacing the bad oil fixes the problem instantly.
John Deere f725 Review
There are mixed reactions about the John Deere f725. The majority of users are happy.
For instance, many owners believe it’s only been around so long because it’s worth the money. Others also say it’s one of the best “workhorses” for the price.
We agree with them. For instance, the powerful engine is a major selling point. At 20hp, it gives you enough power to work on large lawns without straining the mower.
We also love that the f725 offers infinite forward and reverse gears. However, we’re unimpressed by the constant engine issues.
Additionally, John Deere must do something about the blowout issues. So, all-in-all, the f725 is a great lawnmower for medium projects if you’re handy with DIYs.
But note that John Deere mowers users are strictly advised to follow the recommended service schedule outlined in the owner’s manual to enjoy full warranty benefits.
John Deere f725 Parts Diagram
The John Deere f725 has several dozen parts, as shown in the above diagram. So, sometimes finding the right replacement parts can be a challenge.
We recommend two solutions. First, call John Deere customer support. They have an excellent customer support desk, willing to go to lengths to help customers. Alternatively, speak with your dealer.
John Deere f725 Alternatives
We often compare the John Deere f725 to its predecessor, the John Deere f710, and its successor, the John Deere f735.
The f710, first developed in 1991, has been around for more than thirty years. It’s a 17.5hp, one-cylinder Kawasaki engine mower with a 7-gallon fuel tank, a differential lock, and power steering.
Meanwhile, the f735, first made in 1999, is a 20.5 two-cylinder Yanmar diesel engine mower with a 7-gallon tank.
Both are two-wheel-drive mowers, but the f710 has a 535cc capacity while the f735 is a 753cc engine.
Besides the f710 and f735, consider John Deere x700 and z700 series mowers. Series x700 mowers are 4WD units with powerful engines of up to 25.5hp, while z700 mower engines are up to 24.5hp.
The John Deere f725 is a great lawn mower for everyday tasks. Though not the most powerful unit, its 20hp engine allows it to handle small and medium-sized lawns easily.
It’s also a low-maintenance mower with excellent attachments. Of course, it comes with a few issues. But which mower doesn’t?