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The 5320 Operation and Test Manual doesn't show a fuel check valve in the fuel system diagram nor does it mention one in the theory of operation. However, I did locate a fuel check valve this morning. It is located halfway between the fuel tank and the fuel filter. I assume it is there to help hold the fuel prime by acting as a one way gate. I completely removed the six feet of fuel line with check valve today. I'm going to replace the entire piece. A closer inspection of the check valve appears to reveal some of those "filling" or "shavings" on the fuel tank side of the valve. Even though it appear as though it wasn't clogged it is really hard to say for sure as by the time I disconnected the hose, fuel rushing out could have unclogged it. I say this because I blew into it and air seem to come out the other side. But none-the-less there were shavings in the valve and what appeared to be a small piece of straw. This may have been enough to cause the problem as this fuel system relies a bit on gravity and the fuel tank sits lower than the fuel filter. Not the most cleaver design if you ask me. The injection pump has the burden of providing the suction through the filter and to the tank. Oddly, engineers at JD decided in their infinite wisdom to mount a low fuel tank on the left side then run six feet of hose to the right side where the fuel filter sits up higher then run another six feet of fuel tube back to the left side to the injection pump. No wonder the fuel tank needs to be full to prime the filter. Seems like an electric fuel pump would have made life easier.

• Fuel Delivery Problem on a JD 5420

Still the system is a pain in the neck, but reliability is now OK. The fuel filter design makes the filters tough to change and the priming sequence is not exactly user friendly for a single person.

Now my 1997 Ford Powerstroke fuel system is trouble free with 240k miles. Easy filter changes and self-priming. I expected such simplicity out of a high dollar tractor. I was sure to call JD to tell them what I thought when it happened.

I agree with you on the priming issue. How the heck do they expect us to operate the hand pump and watch what is going on with the injection pump when they are on opposite sides of the tractor. Being an engineer myself I'm disappointed with what JD engineers decided to do with this design.