Oil & Fuel JD 855 starting issues

JD_Sheldon · Feb 4, 2017

Hi, well I have had this issue for about a year. Basically the tractor would not start unless I used jumper leads and turned it for about 1 minute. It got progressively worse until it wouldn't start at all. It would crank but not start. I had a tractor mechanic have a look at he thought it was a fuel issue and we ordered a new fuel bowl (as mine was warped). It arrived and I installed it however the issue remained. I then searched the forum and found heaps of great advice and I bled the entire system about 5 times. Still the issue remained. Finally I undid the bleed screw above the mechanical pump (a fuel hose runs from it to the top let side of the pump). It started however as soon as I tightened the screw it stalled. So it starts with the screw undone and as soon as i tighten it it stalls, every time. Any ideas?

the diesel tank is full
I replaced all the fuel lines
I bled the three injectors separately and together
I bled the screws above the fuel bowl

CADplans · Feb 4, 2017

My first guess was the fuel solenoid,, after all that cranking. They will overheat, and burn out.
But, then you said there is a way to get it to start.

Any chance you could post a pic like this,
someone could look at it and make sure all the hoses are going to the right location.

olPete · Feb 4, 2017

When the fuel lines were replaced, did that affect the problem better/worse?
Some JDs larger in size had a little restrictor sleeve in the return line, and had incorrect fuel pressure when the lines were replaced as the restriction wasn't obvious, and not replaced.
Not long ago had major issues with JD6420 and that was found out then, but it needed a new injection pump in the end as the FCV didn't appreciate water in the fuel for many months.

kthompson · Feb 4, 2017

Just wondering how often you are you cranking this tractor? Does it vary with how long since you last ran it? I have different model 5525 and having similar issue and I have learned to use some WD 40 to aid in starting it and or the pump to prime. Mine is acting like there is a very fine leak letting air into the system as it is more of issue the longer the tractor sits between being run.

Egon · Feb 5, 2017

If opening the bleed off will it get a direct supply of fuel that the injection pump can access by suction? If that is the case there is a blockage in the regular fuel system. Solenoid!, Thermistor if it has one? Shut off switch? Loose wire connection? Fuse?

olPete · Feb 5, 2017

Mm or a blocked pickup in the tank..
I'd start at the start. Pull the pickup out of the tank and see if there's a blocked mesh filter. That will tell you what your girl has been drinking over the years.
Neighbour had fuel issues on a 6420. Amazed the 'mechanic' didn't even check the fuel filter bowls or the pickup when he came to diagnose. He didn't come back. I found his had had a long history of wet and dirty diesel when I checked them. And the restriction in the return line had never been noticed of replaced by the other 'mechanic' that replaced the rubber lines! So it wasn't getting enough diesel, and then the lack of restrictor meant it wasn't keeping it there when it got it
Does your tractor have a lift pump? Anyone know?

JD_Sheldon · Feb 5, 2017

That is a good suggestion. I have checked the solenoid and the filter in the bottom of the fuel tank. Both are fine. Now, as for suction, when I pulled the fuel filter out I removed the entire assembly, so the metal top for want of a better term. I did notice that the connection between the fuel line from the tank to the fuel filter assembly was loose and can't be tighten (the inside part of the top where it goes into seems to have worn over time). I assume this would cause an issue on the suction side as it would be sucking air.

JD_Sheldon · Feb 5, 2017

This was an issue before I replaced the fuel lines. I replaced the lines hoping it might fix the issue.

olPete · Feb 5, 2017

JD_Sheldon said:
This was an issue before I replaced the fuel lines. I replaced the lines hoping it might fix the issue.

Hmm good work there. It could well be an air problem if it's loose enough to see.
You would assume that it would be letting the fuel drop right back to the tank if that's the case.
That would certainly cause issues at startup if it has to drag fuel all the way through the system to fill the injector pump, and let air bubbles into the filters and pump.
The tractor we had trouble with, had an electric lift pump with a filter before and after it, so you could leave the key on for a minute or so while it got up to pressure before starting. It would also help with bleeding the injector pump.

olPete · Feb 5, 2017

JD_Sheldon said:
That is a good suggestion. I have checked the solenoid and the filter in the bottom of the fuel tank. Both are fine. Now, as for suction, when I pulled the fuel filter out I removed the entire assembly, so the metal top for want of a better term. I did notice that the connection between the fuel line from the tank to the fuel filter assembly was loose and can't be tighten (the inside part of the top where it goes into seems to have worn over time). I assume this would cause an issue on the suction side as it would be sucking air.

You might need to replace or repair that worn part. I suspect that's your issue.