John Deere 4840 has been in the shed all summer, I needed to move it to store things for winter. Now it does not start. It was bought at auction several years ago and I don’t know the history, etc. Looks like the pump has been off before we had it. This machine has never been the easiest to start, but it always did. This is what it does.
It starts very well and seems to be fast enough, but when the fuel cut-off is pressed, there is a noticeable deceleration in starting speed, almost as if it gets bogged down. First you get a light gray smoke and it quickly turns to a thick black and comes off, never hitting enough to boot. It seems to have been flooded.
Is it time to rebuild the pump, or do you think there is another problem that is being missed?
- I’d put a battery charger on it, and plug in the block heater if it has one. Pump the priming pump until you see fuel re-enter the tank through the return line, then try to start it.
- Check the intake system. something might have blocked the fit during the summer and not getting any air.
- All you’re doing when starting something is cranking the engine by driving it backwards instead of with a starter. If it doesn’t turn on, it still won’t turn on.
- Checking the air intake and finding a mouse nest or something like that is surprisingly common. Black smoke means you’re getting fuel, and it’s hard to believe you’ll lose enough compression from sitting to go from starting to not. . but you have to check it. I know that I get most of the black smoke when an air filter is clogged. Good luck, let us know what you find.
- I’d put a battery charger in it, and plug in the block heater if it has one. Pump the priming pump until you see fuel re-enter the tank through the return line, then try to start it.
- Check the timing, if it is idle for a long time it may need the injectors to be cleaned, do you have good fuel flow to the injectors? Take out the injectors and squirt a couple into the cylinders. Don’t let them get soaked, give it a spin as soon as you put it back together. This will force the oil to the area that needs attention. 4840 good tractor should be working and not sitting under a shed.
- The compression or leak test on the cylinders will tell you a lot.ps if you have been sitting over time the barrels and plungers in the pump can varnish and restrict fuel flow. If you leave it standing for a long time, fill the tank to the top.