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Just writing this is going to stress me out. Harvest is just around the corner and once again I will have to deal with a mysterious engine issue on my 9600. I used to love this old girl but last fall my trusty TR99 stomped her into stubble and left her to sit and watch the yellow twin spinner finish the harvest. The 9600 has certainly been reliable in the past but the last year was pretty much a disaster.

Two years ago on the last day of harvest the combine just up and quit on me under full power in the field. I figured it was probably a fuel filter so I put on a new rectangular block filter which did not solve the problem. I had fuel to the filter block but couldn't get any by it. I started taking things apart and discovered that there is a little check valve in the filter block housing that had been pushed back wards through its hole so that it was actually checking the flow in reverse preventing the fuel from leaving the filter block. I removed the check valve (the spring was ruined and not repairable) and the combine started up and I finished the harvest. I also figured the fuel might leak down to the tank with the check valve removed so I shut the fuel off using the valve at the bottom of the tank at the end of each day.

At the start of last harvest I figured I would fix the problem by getting a new check valve. I went to a wrecker and purchased the entire filter block with check valve and installed it. The combine fired up and we took it to the shop to grease, etc. When it was ready for the field we took over to fuel it up and shut it off. When we tried to start it again it would not go. I got investigating and found that the check valve in the filter body was again pushed backwards through its hole and was preventing the fuel from getting to the injector pump. I removed the check valve again and it started up. A few hours later it quit again, I began talking to the "experts" and was told it may be the fuel shut off solenoid and to remove the plunger. With the check valve removed and the Fuel shut off solenoid plunger removed I wondered how it could shut off etc, but apparently the ECM electronically shuts off the fuel rack inside the injector pump and it will still shut down and start normally.

But the old 9600 still just quit, sometimes after an hour, sometimes after a day or two. The next time it quit we were told we may have bad ground or battery connections. So we removed the ground cables from where they attach to the combine and cleaned everything and had full voltage, We cleaned the connectors from the computer mounted on the back wall and it all looked fine. We took out the circuit board with the relays and tried mixing and matching relays for the fuel pump etc. and cleaned everything and still no better. We traced the wiring harness looking for frayed wires etc., and could find nothing out of the ordinary.

We thought maybe the fuel tank vent was plugged so we removed it from the tank and cleaned it and although it was a bit dirty it did not fix the problem. We thought maybe the line coming out of the tank was plugged so we removed it and fuel flowed freely from it. We also blew compressed air though the hoses and into the tank and found no restrictions. I purchased a new water separator filter and installed it and it did not help. We then purchased a new lift pump and installed it but that also did not work.

We noticed that the block filter up top was always leaking and seemed to be under pressure. Sometimes we would just remove the filter and reinstall it and the thing would fire up. I figured maybe the filter block housing was worn and couldn't make a seal. So I went to JD and bought a new filter housing and new filter and installed it, it immediately pressured up and began leaking. I put my old filter block back on from the wrecker and let the diesel drip all over the engine bay hoping for a fire. After 10 or 20 shut downs we could sometimes get it going by replacing the block style fuel filter I carried a couple in my truck and would just switch the around didn't matter if they were used or new they might cause it to start or maybe not, no rhyme or reason to it. Sometimes i just dumped the fuel out of the filter and reinstalled it and it would run, seemed like letting the pressure off or something would change something. We did managed to get a hundred or so hours out of her before we gave up so had plenty of good new fuel. Also no water in separator and I have a filter and separator on my farm tanks.

The JD techs came out three times, they thought that it may be a weak pressure relief valve on the return line of the injector pump letting all the fuel dump into the return line instead of making it to the high pressure pump side. It cost 560 dollars for the little valve but it didn't do a thing. Then they thought it may be the hand priming pump cartridge so i bought one and installed it and of course it didn't work. I stuck a magnet into the bottom of the injector pump to look for iron filings as a diesel injection expert instructed me to do but there were no filings.

I now suspect the little housing the priming pump cartridge mounts on the side of the injector pump as apparently there is a lever on it that pumps fuel using a cam inside the injector pump. There is a seal there that actually seals fuel out of the crank case oil that lubricates the injector pump. I wonder if it could be letting in air. They also say that when this seal is gone it will let diesel mix with your crank case oil and thin it down. I kind of thought this might be happening but it must have been a slow drip maybe a litre or two all day unless I'm dreaming or it was evaporating.

When the engine starts after sitting a while it stumbles and nearly runs out of fuel then catches itself and runs like a top. There is no smoking or anything when it is running good and it has good power. There is about 4000 engine hours on the machine. The Diesel Injection guys say that a stuck open injector could not push pressure back into the system and blow the check valves up or blow the filter seals.

I should mention that this spring I fired it up and used it to combine flax for three days it quit once in the first hour and then never quit again. I also used it to harvest some wheat and did some Kochia weed that was in my way prior to seeding and it ran like a top. We have moved it around the yard several times and it is hasn't quit again. Also the filter seal has quit leaking for some reason. I am baffled, yes it is working now but I do not trust it as nothing I have done has immediately fixed it and it still stumbles when you try to start it. What could this be, ECM? I can't see how it could be as that could not create pressurized filters and stumbling fuel starved starts? or could it. Injectors? no smoke, smooth operation, lots of power, injector pump? Just don't know. Please help, 9600 for sale cheap.
 

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Have you checked the solenoids beside the batteries? One of them is power from the key. Our 9600 did the same thing. I jumpered out one solenoid at a time to find the culprit. For some reason they get weak and come unlatched??
 

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Well lets start with what is known for sure.
You know the filter is being over pressurized due to the leaking filter seals and the damaged check valves.
So tee a manual gauge into the lift pump circuit pressure side with a clear line so you can see whats happening.
What regulates the charge pressure?
I agree around 4000 hrs or so the Bosch pumps tend to give trouble usually the pump crank bearings start to go the first sign of that is the filings get stuck on a speed sensor and set a fault code on the display.
 

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It almost seems to me that this is a fuel system problem first.
The reason why I came to that conclusion is you say it starts then nearly dies like it is fuel starved.
That tells me you have air in the system.
But the fact that you have what sounds like over pressurized lift pump pressure leads me to believe that the return line to the tank is restricted or the return pressure valve has junk in it.
Possible rubber chunk or piece of junk or something momentarily restricting the return fuel?
I think by pumping the hand primer manually with engine off you should be able to hear that return pressure valve chatter as you pump and fuel flows back to the tank.
 

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Discussion Starter #7
It almost seems to me that this is a fuel system problem first.
The reason why I came to that conclusion is you say it starts then nearly dies like it is fuel starved.
That tells me you have air in the system.
But the fact that you have what sounds like over pressurized lift pump pressure leads me to believe that the return line to the tank is restricted or the return pressure valve has junk in it.
Possible rubber chunk or piece of junk or something momentarily restricting the return fuel?
I think by pumping the hand primer manually with engine off you should be able to hear that return pressure valve chatter as you pump and fuel flows back to the tank.
Yes you are correct when I pump the manual primer pump I can hear fuel going back into the tank and I replaced the return line pressure valve that was the $560 valve I mentioned that is on the side of the injection pump that did not work I have not tried a manual gauge on the line to test the lift pump however I how ever I replaced the lift pump and it is self-regulating pressure I tested the solenoids down by the batteries as well it may be an intermittent problem but they seem to be working fine
 

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Discussion Starter #8
I also thought that maybe it could be a possible chunk of rubber that restricts the line momentarily and when I pull off the filter it lets the fuel back and releases the rubber chunk but if it is in there I can't find it it could be the inside of a hose to I may investigate that further
 

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just looked at the 9600 parts book.
Thought possibly a problem with the return line to tank shows a shut off valve and that the return hose pushes onto a barbed fitting at the tank.
Hose wouldn't have got shaved or rubber jamming there would it?
 

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Return line #2
Check the return for free flow back to the tank.
Deteriorating rubber hoses, restrictions at bend or fittings like #22 or # 21 comes to mind.
could be as simple as a swollen wheat seed jamming things up in a fuel line.
 

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however I how ever I replaced the lift pump and it is self-regulating pressure
Uhm this has me confused a bit.
Which lift pump got changed?
There are two.
Electric pump on the body of the combine near the fuel tank.
That electric pump is a low pressure supply self regulated that feeds fuel to the fuel transfer pump on the side of the injection pump where the hand primer is and is a positive displacement piston type pump.
Fuel goes from the fuel transfer pump to the square fuel filter at a higher pressure.
That fuel is what feeds the injection pump plungers and is regulated I suspect by the $560 pressure regulating valve that got changed.
Excess fuel flow from that transfer pump must go to the tank freely after it overcomes the spring pressure of the regulating valve.
Or what will happen is it will blow seals at the rectangular fuel filter.
Which is what you seem to have happening.
 

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are you sure not elecritcial, there is a lead coning out of the positive cable it is moulded into the clamp, mine was corroded inside and caused a similar issue. Cut the wire and extend it and put it direct to battery.
 

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are you sure not elecritcial, there is a lead coning out of the positive cable it is moulded into the clamp, mine was corroded inside and caused a similar issue. Cut the wire and extend it and put it direct to battery.
Oh anything is possible.
I wouldn't rule out electrical either just yet.
However electrical doesn't cause fuel filters to leak and check balls forced through their springs.
Could have multiple issues.
Have to start with what you know is wrong first.
 

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MF cowboy , I don't quite have the same problem but on my john deere 9650 walker combine, which is pretty much the same as a 9600, I have a problem with fuel bleeding back to the tank. If I leave the combine parked for more than two days even with the fuel shut off switch closed at the tank it will not start. It tanks about 3-4 minutes of pumping the hand primer to get it going. Otherwise when its running I have no problems with power. John deere mechanic said the brown electrical connections were poor on the fuel pump. Is there any other possibilities why the combine loses prime.
 

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MF cowboy , I don't quite have the same problem but on my john deere 9650 walker combine, which is pretty much the same as a 9600, I have a problem with fuel bleeding back to the tank. If I leave the combine parked for more than two days even with the fuel shut off switch closed at the tank it will not start. It tanks about 3-4 minutes of pumping the hand primer to get it going. Otherwise when its running I have no problems with power. John deere mechanic said the brown electrical connections were poor on the fuel pump. Is there any other possibilities why the combine loses prime.
I'm not as familiar with the 9650.
There were changes to the injection systems on those depending on serial number.
See here.
 
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