John Deere 6420 fuel problems

[PhillipD24]

I have a JD 6420 that started running rough replaced both fuel filters. Noticed that fuel does not come out bleeder on filter nearest the cab. Checked fuel pump and it appears to be working good. Can work with filters ie refilling filters and working with bleeder to get air out and tractor will start and run perfect all day long after sitting over night same problem. Have problem with fuel gauge not registering correctly (showing empty) then it goes back to working. Got fuel sensor switch code yesterday and gauge for water in bowl, blinks when running rough. have check fuel lines can't find any leaks, acts like it getting air some where. Anybody have any ideas? What happened to the good ole days before computers.

 

[MightyReek]

NEVER open the filter near the cabin, it would only suck air into it because the pump is ahead of it, sucking...
To bleed open the front filter, choose the screw that has an arrow pointing out of the filter.

If you have a leak in the "suction side" of the pump you won't notice it, and over night you'll have air in the system.

Many times, the fuel line that connects the tank to the first filter has a leak provoked by the wider part of the fitter (if you open the hose with your knife you'll notice something like a needle hole). Have that fuel line replaced and also the one that connects that first filter to the pump.

Anyway, if the "engine controller bulb" is flashing you MUST check the diagnostic codes in the ECU. You may have some other problem with the injection pump in the worst scenario...

If you find the problem, please come back with the answer, people always likes to know.
Good luck

 

[JasG]

NEVER open the filter near the cabin, it would only suck air into it because the pump is ahead of it, sucking...
To bleed open the front filter, choose the screw that has an arrow pointing out of the filter.

If you have a leak in the "suction side" of the pump you won't notice it, and over night you'll have air in the system.

Many times, the fuel line that connects the tank to the first filter has a leak provoked by the wider part of the fitter (if you open the hose with your knife you'll notice something like a needle hole). Have that fuel line replaced and also the one that connects that first filter to the pump.

Anyway, if the "engine controller bulb" is flashing you MUST check the diagnostic codes in the ECU. You may have some other problem with the injection pump in the worst scenario...

If you find the problem, please come back with the answer, people always likes to know.
Good luck

This tractor should have a lift pump in the tank that pushes fuel through the filters to the injection pump. With the key in the run position engine off he should be able to open the bleed screws on either filter housing, one at a time and bleed air out.

 

[JasG]

I have a JD 6420 that started running rough replaced both fuel filters. Noticed that fuel does not come out bleeder on filter nearest the cab. Checked fuel pump and it appears to be working good. Can work with filters ie refilling filters and working with bleeder to get air out and tractor will start and run perfect all day long after sitting over night same problem. Have problem with fuel gauge not registering correctly (showing empty) then it goes back to working. Got fuel sensor switch code yesterday and gauge for water in bowl, blinks when running rough. have check fuel lines can't find any leaks, acts like it getting air some where. Anybody have any ideas? What happened to the good ole days before computers.

There should be fuel coming from the bleed screw with the key on. Did you try removing the screw to see if some how it is plugged? I would replace the fuel lines and also we added a check valve that the tractor did not come with about 6" from the filter, between the filter and the tank. Ours is a different model tractor, but should be similar on fuel delivery as far as I can tell. Ours had similar symptoms, fuel line was bad, but not leaking enough that we could tell till we cut the outer cover off. At the time re replaced the line, the dealer said we should add the check and we did. Hopefully that is all it is.

Can't help you with the fuel guage though.

 

[MightyReek]

This tractor should have a lift pump in the tank that pushes fuel through the filters to the injection pump. With the key in the run position engine off he should be able to open the bleed screws on either filter housing, one at a time and bleed air out.

With two fuel filters there is no lift pump inside the tank but a transfer pump attached to a plate between the chassis and the engine block.
Like this:

 

[JasG]

With two fuel filters there is no lift pump inside the tank but a transfer pump attached to a plate between the chassis and the engine block.
Like this:

If that is the case, then how do you bleed the system?

The manual I looked at just says the system could have 1 filter or 2 filters and does not say there is a difference. The tractor I work on has just 1 filter with an in tank pump.

 

[MightyReek]

If that is the case, then how do you bleed the system?

Open the "fuel exit" in the front filter.
The filter support has 5 connection points.
The usual bleeder is connected to pump's return.
Then you have two entrances, one is connected to the transfer pump, the second is blocked.
You have two exits, one is connected to the injection pump and the second is blocked. You remove the screw from this one witch is blocked.
There are small arrows over these exists/entrances pointing in and out.

Opening the rear filter would result as pulling the pump out of the tank in your tractor.

 

[JasG]

Open the "fuel exit" in the front filter.
The filter support has 5 connection points.
The usual bleeder is connected to pump's return.
Then you have two entrances, one is connected to the transfer pump, the second is blocked.
You have two exits, one is connected to the injection pump and the second is blocked. You remove the screw from this one witch is blocked.
There are small arrows over these exists/entrances pointing in and out.

Opening the rear filter would result as pulling the pump out of the tank in your tractor.

With your drawing I can see that.

I wonder if there is a difference between US and Euopean models? Like I said my manual only states you may have one or 2 filters and it is suppose to cover this model tractor.

Thanks for the info.

 

[MightyReek]

I've check it, if you look in online parts catalogue Section 30 - ENGINE AUXILIARIES, TANK, AIR SYSTEM, page 269 - FUEL HOSES (WITH TIER II ENGINE) there is the same image I put here.
Offcourse, this is variable according with the injection system in the tractor.
This is valid for Tier II Injection Systems (HPCR common rail level 11 and Stanadyne DE10 level 12) and Tier 3 (6030 series) both 14 and 16 levels.

Tier 1 Bosch VP44 level 4 won't have this (has a different transfer pump is mounted on top of filter "head").

 

[robert clarke]

I bought a used JD 6420 and had the same problem. The injector pump had no paint on it - so it had been removed and checked over. The same with injectors and all the fuel lines from the injector pump to the injectors - no paint - so they were checked over also. Also, all the rubber fuel lines had been changed. Like you, I changed the fuel filters and there was no change. The little fuel pump was woking all right. Was looking at this thing and trying to figure out what was the problem, when I noticed that after the fuel line came back up from the little electric fuel pump, there is a tee in the fuel line. This is only about 2 inches above the frame of the tractor. Off of this tee, the line Goes on up to the first fuel filter- about 10 to 12 inches of lift. Now, If you go back down to the tee in that line, you will see that a line goes off the tee and straight level across toward the back of the engine and goes into another tee. That line is the return line to the fuel tank. Much easier for the fuel to just return to the fuel tank than to try and lift up to the fuel filters and go through the filters and injector pump and the rest of the system and then back to the fuel tank. Is that line below the fuel filter at the tee, going over to the return to the fuel tank, necessary. I pinched the line off with a pair vise grips to see if the tractor would run properly. I turned the ignition key to the on position and let the electric fuel pump run for a miniute or so to chase any air out of the system and then started the engine. Tractor ran perfectly, which proved that the engine was not getting enough fuel. After talking to the local JD dealer parts people, I find that the line over to the return is a necessary part of the system - an excess flow line. "BUT" there must be a flow restrictor in that line to limit the amount of fuel that can return to the fuel tank. This forces more fuel up to the fuel filters so the system gets enough fuel to make the engine work properly. You cannot eliminate that line going over to the return to the fuel tank or you may make the little electric fuel pump work too hard. The flow restrictor is about 1.5 inches long and is just like a little piece of copper tubing that you would use to join two pieces of the rubber fuel line. Looks like it is made out of brass. Just cut the fuel and insert the flow control restrictor and a couple of clamps and you should have your problem solved. I also added a one way flow valve into my system as an extra measure. It also goes into the fuel line, between the fuel tank and before the little electric fuel pump. Again, all you do is cut the rubber fuel line and it just inserts into the line like the flow restrictor. This just makes sure that the fuel cannot drain back down into the fuel tank - thus keeping the line always full of fuel. The one way valve was $4.50 CAN. and the flow restrictor was $29.95 CAN. Tractor runs the way it should now. Hope this helps you.

 

[robert clarke]

Just noticed the diagrams in this site after I entered the posting. Look at the diagrams and you will see the flow restrictor valve that I was talking about. It is #6. One end is completely open but the other end is closed off with a smaller hole drilled in it, to reduce the flow getting back to the return line and on into the fuel tank. Also I got the prices reversed for the one way valve and the flow restictor valve. One way valve $29.95 CAN. and flow restictor valve $4.50 CAN. If you want to see if that line letting fuel get back to the return line and to the fuel tank is the problem, before making any investment in parts, - just use your vise grips and clamp that line closed so nothing, or very little fuel can get back to fuel tank, - and run electic fuel pump for a minute or two before starting engine. If the engine runs properly then you just proved to yourself that you need that part #6 - the flow restictor valve. I just think the one way flow valve is also a good idea for all it costs.

 

[robert clarke]

Also see my 2nd reply at bottom right as part 2 of 2. My tractor has 2 fuel filters and an eletric fuel pump between the frame and the motor. I have pulled the fuel gage out of the fuel tank and there is no lift pump on that assembly. That is why I think it is a good idea to have a one way flow valve in the line. Would likely be best at the bottom of draw line in the fuel tank - sort of like a foot valve at the bottom of a water well. It stops any fuel from draining back down into the tank and always keeps the fuel lines full. I put my one way valve in the draw line, as I said earlier, up by the back of the engine where the line comes out from under the cab,and from the top of the fuel tank. It is easy to do at that point and works just fine. You must make sure that you do this on the line that goes down to the end of the electric fuel pump (closest to the cab). That is the draw end of the pump. The hose coming up from the other end of the pump - toward the front end of the engine, is the pressure side and goes up to the fuel filters. If you lift the thick floor mat in the cab ( clutch side) and lift the plastic piece (about 5" by 6") you will be looking down on top of the fuel unit on the top of the fuel tank. There are two metal pieces where the rubber fuel lines connect on to.They will be pointing toward the front of the tractor. The one closest to the steps (clutch side) is the draw line going to the fuel pump. Make sure you follow this line right out from under the cab to the fuel pump (the two lines can be crossed under the cab and you would be hooking the wrong line to the fuel punp). This line closest to the step goes down into the tank and has a plastic cage with integral screen at the bottom of the drop tub in the tank. The return line is just a piece of rubber line that drops down to the bottom of the tank. If you take these simple steps I think many people will solve their problems. I think that in many cases, - the engine is not getting enough fuel (sort of like the way it sound when running out of fuel). Not air getting into the system but a FUEL shortage.

 

[MightyReek]

From my experience I wouldn't recommend putting the one-way valve in the suction side of the pump.
Eventually the spring will get rusty (at least around here fuel always gets some residual water) and the ball will get "stuck" with the rust, and the pump won't have enough suction to "unstuck" it...
You might get it to work fine in first times, but you will eventually have problems.
And if you have a leak in the hose ahead of the valve you'll get air inside anyway.

If you want to put the one-way valve I'd recommend put it after the last "T-connection", in the line heading to the final fuel filter. In this fuel system the one-way valve isn't as efficient as in the "pump-in-the-tank" system...

 

[robert clarke]

Undoutedly, having a lift pump in the bottom of the fuel tank would be the best idea. According to the diagrams ( likely JD) on this site, the routing of the fuel lines on my used JD 6420 has been changed - likely when they replaced all the rubber fuel lines. My draw line from the fuel tank goes directly to the electric fuel pump - not to the first fuel filter like in the diagram. I suppose the idea of going from the tank to the first filter, before going to the electric fuel pump, would be to save the fuel pump from getting any wear from dirt particles. Other than that, my system works just the same. When people decide to replace all the rubber fuel lines, - probably all the lines are just cut out and thrown away as one unit. It would be easy to not realize that there was a flow restrictor valve in the system, as is shown in the JD parts diagrams, and thus the start of the engine running rough problems. The JD diagrams on this site show a one way valve (part # 45) in the system, ( as they obviosly come out of the factory), so it is conciderd a neccesary part. That diagram shows the one way valve as being between the fuel tank and the first filter. If you put that valve between the first and second filter, then you are leaving a lot of the fuel system with no protection against back draining back into the fuel tank, - and if that part of the system develops a problem, then you could be right back to the same old problem of a rough running engine. If the one way valve is getting to the point of ceasing up, - it may work a little longer on the pressure side of the electric fuel pump, - but that is likely only a matter of time before it causes the same problem anyway. You may be right about the one way valve ceasing up in the future, but if that happens, - then it is easy to put another new one in the fuel line. The real point is that JD shows a one way valve as part of their system, - so that is likely the lesser of two evils.

 

[PhillipD24]

Well I gave up and called the dealer, They replaced the injector pump and is running fine so far. Haven't got the bill yet but rebuilt pump quoted at about $1700.00. Thanks for you help and advice.

 

[Tx Jim]

$1700 WOW. I'm glad my '91 model JD has no computer to depend on for it to run.