This post could apply to other John Deere tractors but it is written specific to the JD 5x20 series (5220, 5320, 5420, 5520) tractors as I own a 5320 model. You may find that your non-5x20 tractor exhibits similar problems and may find this information helpful in your diagnostic process.
There are a number of reasons why a 5x20 series tractor may experience startup problems. This post will cover a few of the most basic of those issues experienced with what would otherwise be considered equipment in good working order and not experiencing engine component failure.
FAILURE #1
The 5x20 series tractor is notorious for startup problems relating to it's inherently poor fuel system design. Specifically, the 5x20 series tractor does not have a fuel pump but rather relies on a gravity fed system plus some minor suction from the fuel injector pump. The 5x20 series tractor design places the fuel tank approximately level or below the fuel filter and fuel injector. Because of this AND coupled with the lack of a fuel pump a common complaint is that the fuel system loses it's prime. The problem is observed much more when the fuel tank is allowed to get to half full or less AND the tractor is allowed to sit over an extended period of time. Loss of fuel prime requires the operator to go through the fuel system priming process and may involve two or three minutes of accumulated engine turnover before the fuel prime is restored and the engine fires.
Refer to your owner's manual for the fuel system priming process. Note: the injection pump is self priming however you must loosen the bleed screw on the injection pump and force any air out of the system by operating the hand pump on top of the fuel filter assembly.
It is hard to say why the 5x20 series tractors sometimes lose their fuel prime. Theoretically this should not happen. However, it does happen and John Deere has acknowledged this issue by generating a service solution. Refer to John Deere technical solution #54399. This solution involves the installation of an electric fuel pump. The John Deere part number for the fuel pump is KV13829. It costs approximately $90.
FAILURE #2
The 5x20 series fuel system includes the use of a check valve between the fuel tank and the fuel filter. This check valve is meant to provide a one way directional flow of fuel from the tank to the filter. Fuel can only pass in one direction and the check valve is there to prevent fuel from flowing the opposite direction and thus a loss of fuel prime. However, as we know from above, the 5x20 series can and sometimes does lose it's prime. Unfortunately, this check valve can get plugged up and thus blocks the delicate flow of fuel from the tank to the fuel filter. This blockage can eventually prevent your tractor from starting up.
Not only can this check valve get plugged up with debris introduced by the operator but it may, in fact, get plugged up by debris in the fuel tank left over from the manufacturing process. Yes, this means that for some folks their check valve is getting plugged up because of poor manufacturing processes at the factory or sloppy workmanship. Specifically, the fuel tank on this series of tractor is made of a polymer plastic type material. When fuel line tap holes are drilled into the newly manufactured tank it isn't uncommon for some of these plastic shavings to remain in the tank. Eventually and over time these small shavings may end up clogging the fuel line check valve. To fix the problem either clear the check valve by removing it and blowing compressed air though it or more appropriately replace the check valve. JD part #AL117189 is a simple plastic check valve that sells for approximately $12 at your JD dealer.
In addition, you may find that debris has also found it's way into the fuel hand priming pump located on top of the fuel filter. The priming pump is easily disassembled for cleaning without tools. Simply unscrewed the plastic ring sitting around the pump remove all the components and clean before reassembling. Pay attention to how the parts are assembled during the cleaning process.
FAILURE #3
If the issues above are not your problem, that is, you don't have a clogged fuel system and you have re-established the prime by performing the priming procedure then the problem could be the fuel shutoff solenoid. The fuel shutoff solenoid is responsible for shutting off the flow of fuel to the injection pump when the key is turned to the OFF position. When the key is turned to the ON position the solenoid makes a "click" sound as the fuel is allowed to flow into the injector pump as the solenoid activates. If you don't hear a "click" sound when you turn the key to the "ON" position it is possible that the either the fuel shutoff solenoid needs to be replaced or electric current is not flowing from the key switch to the solenoid.
You can test the solenoid directly without involving the key switch circuit. To do this make sure the key in in the OFF position. Take a long wire or jumper cable and connect one end to the positive (+) terminal of your tractor battery. Touch the other end of the wire or jumper cable to the positive (+) terminal of the fuel shutoff solenoid. You should hear it "click" as the solenoid activates. If this occurs then your fuel shutoff solenoid is in good working order. Otherwise you will need to replace the solenoid. If it is established that the fuel shutoff solenoid is good the next thing to check will be the fuse for it in the fuse box. Refer to your owner's manual for location of the fuel shutoff solenoid fuse or look on the back of the fuse box cover for a fuse map. If the fuse is blown replace it. If the fuse is good then the key switch may be bad.
OTHER ISSUES
Hopefully, if you had a problem starting up your JD 5x20 series tractor, the three solutions above took care of your issue. If not, then obviously the problem could be a lot more complicated or expensive. I won't cover those possible issues here but the problem may be:
1. Cold climate and glow plug failure.
2. Injector pump failure.
3. Injectors clogged.
Good luck. I hope this post helps someone. If anyone wants to post follow up information or additional useful info then please do so.
