Losing fuel pump prime

My JD 5420 has started to lose fuel prime when it sits overnight. A quick bleed and a couple dozen pumps and it will start right up and run fine. The tractor will start all day but lose prime overnight.

It happens when sitting level, does not happen as much when sitting on a slope with the left side lower, I do not keep the fuel tank full, seems to happen less when the tank is more than half full.

Any ideas what is causing this and what to do?

I have had to change the fuel lines on a lot of them, seems the cloth coated ones get porous and let the fuel leak back, change the lines out with a good quality line from a auto parts store and it should be okay.

I had the same problem with my 5520. This series has a problem because there is no transfer fuel pump in the system. John Deere recommended new lines and installation of a check valve near the tank. After that I've had no problem.

Jumping in a 12 volt fuel pump would help too...but the lines are "crapp"..Deere has been letting us down on quality lately...I really hate to see that happen but it is...I just changed the knotter drive wheels on a 428 baler that is on it's second season, less than 30,000 bales, the castings are soft, the lobes wear down and then the wiper arm losses it's stroke..older balers around here have the original wheels and are like new..China products come to mind??

Yeah Tim I know what you mean about quality. I'm really fearful about Deere's quality. We're still hanging onto all of our 10 through 60 series tractors, - keep them serviced and clean, - because the new stuff is so unpredictable. Deere is going to get their butt kicked by the competition if they don't provide the quality for the money.

Every one is "Drunk" on this electronic binge..and it is creating a lot of Ghostly problems...In a few years we will be figuring out ways to get them back to manual control...

You might want to consider re-plumbing the return line to the tank such that it returns the fuel to the bottom of the tank instead of just dropping it in at the top as per typical, which allows the system to bleed back air into it in the first place. Reliable check valves at these picayune back pressures and flow volumes are impossible to manufacture, but they still sell them all day long. Put in three, none will actually work. Been there, done that and tried to even make my own - still no joy. Cheapest solution will be to re-plumb return line to start with.

It took them decades to finally move to electric transfer pumps and this simple trick is STILL not standard. I shake my head in disbelief, they WANT to make life for us more difficult, we are supposed to have the IP overhauled instead of them spending a dollar when it was new to plumb it so it would work as long as possible easily.

I still contend the huge valve problems beset upon us from Detroit in the 70s was due to the collapse of the steel industry here and the resulting cheaper cast iron for heads which did not take to valve seats directly ground into them as the older cast iron heads were done. Lot of BS about lead in gasoline removal comes from this problem and I believe it was cheap cast iron mainly. Now I see 100,000 mile spider gears that are NOT machined on the gear faces, they are sintered production cheapies and they can NOT last more than 100,000 miles on average. Sad state of affairs, $30,000 trucks built from 2 cent parts and they insist on calling it progress.

How big a job is changing the lines? Do I need to get the dealer to do it?

No it's an easy job..get a rough measurement of the lines and go to an Auto parts store and get the line from bulk, and new clamp, pull one at a time and replace them..